brown rice research paper

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Publications
Account settings
My Bibliography
Collections
Citation manager

Save citation to file

Email citation, add to collections.

Create a new collection
Add to an existing collection

Add to My Bibliography

Your saved search, create a file for external citation management software, your rss feed.

Search in PubMed
Search in NLM Catalog
Add to Search

Brown Rice Versus White Rice: Nutritional Quality, Potential Health Benefits, Development of Food Products, and Preservation Technologies

Affiliations.

1 College of Grain Science and Technology, Shenyang Normal Univ., Shenyang, 110034, Liaoning, China.
2 Dept. of Food Science and Technology, Faculty of Agriculture, Assiut Univ., Assiut, 71526, Egypt.
PMID: 33336992
DOI: 10.1111/1541-4337.12449

Obesity and chronic diet-related diseases such as type 2 diabetes, hypertension, cardiovascular disease, cancers, and celiac are increasing worldwide. The increasing prevalence of these diseases has led nutritionists and food scientists to pay more attention to the relationship between diet and different disease risks. Among different foods, rice has received increasing attention because it is a major component of billions of peoples' diets throughout the world. Rice is commonly consumed after polishing or whitening and the polished grain is known a high glycemic food because of its high starch content. In addition, the removal of the outer bran layer during rice milling results in a loss of nutrients, dietary fiber, and bioactive components. Therefore, many studies were performed to investigate the potential health benefits for the consumption of whole brown rice (BR) grain in comparison to the milled or white rice (WR). The objective of this work was to review the recent advances in research performed for purposes of evaluation of nutritional value and potential health benefits of the whole BR grain. Studies carried out for purposes of developing BR-based food products are reviewed. BR safety and preservation treatments are also explored. In addition, economic and environmental benefits for the consumption of whole BR instead of the polished or WR are presented. Furthermore, challenges facing the commercialization of BR and future perspectives to promote its utilization as food are discussed.

Keywords: brown rice; chronic diseases; dietary fiber; health benefits; nutritional quality; white rice.

PubMed Disclaimer

Grants and funding

Z18-5-019/Shenyang Scientific and Technological Achievements Transformation Program
Shenyang Distinguished Professor Program
EG-16-004/Chinese Ministry of Science and Technology

LinkOut - more resources

Full text sources.

Citation Manager

NCBI Literature Resources

MeSH PMC Bookshelf Disclaimer

The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Unauthorized use of these marks is strictly prohibited.

Ready to eat shelf-stable brown rice in pouches: effect of moisture content on product’s quality and stability

Original Paper
Published: 15 September 2021
Volume 247 , pages 2677–2685, ( 2021 )

Cite this article

Enrico Federici 1 , 2 ,
Valentina Gentilucci 1 ,
Valentina Bernini ORCID: orcid.org/0000-0002-2255-4384 1 ,
Elena Vittadini ORCID: orcid.org/0000-0001-9181-0815 3 &
Nicoletta Pellegrini ORCID: orcid.org/0000-0002-9178-5274 4

4618 Accesses

5 Citations

Explore all metrics

Despite several nutritional benefits of brown rice (BR) its consumption remains limited compared to white rice. Two of the major barriers to its consumption are long cooking time and limited shelf life. However, those two hurdles can be overcome through the development of shelf-stable BR pouches to create new ready-to-eat (RTE) products, a food category that is gaining important market shares. Nevertheless, scarce information is available on the production and shelf-life stability of ready-to-eat BR products. The first objective of this study was the determination of the optimal moisture range to fully cook BR. The second objective was to determine the effect of moisture content and storage time on two fundamental parameters for consumer’s acceptance of rice: color and texture. Three RTE BR pouches with moisture contents of 54%, 57% and 60% were produced and texture and color were evaluated after 1 year of storage. Significant changes in hardness and stickiness were reported during long-term storage. Moisture content negatively affected hardness and positively affected stickiness. Furthermore, storage time and moisture showed a significant effect on rice color. The present results provide information that will be useful to design new RTE meals to promote brown rice consumption.

Development of a functional rice bran cookie rich in γ-oryzanol

Sensory Evaluation, Shelflife and Nutritional Composition of Breadnut (Artocarpus camansi) Cookies

Defatted rice bran as a potential raw material to improve the nutritional and functional quality of cakes.

Avoid common mistakes on your manuscript.

Introduction

Ready-to-eat (RTE) meals are becoming popular among consumers due to their convenience and the change of eating habits. The busy lifestyles of young professionals and entrepreneurs have accounted for an increase in the demand for labor-saving RTE meals [ 1 ]. Availability of RTE meals has further gained importance in light of the COVID-19 pandemic, as they provide not only an easy solution to the need to minimize handling and contact-free delivery of food but also are a lunch option alternative for individuals who would have normally fed at restaurants that have been largely shut down [ 2 , 3 , 4 ].

Rice is a popular ingredient in RTE food in Europe, America and Asia [ 5 ], and it is commonly consumed and used in RTE as polished (white) rice. White rice is preferred from consumers to brown rice (BR) since the latter has a longer cooking time, chewy texture, and poor appearance [ 6 , 7 , 8 ]. Moreover, products incorporating BR also negatively impact the flavor of a product [ 9 ]. However, BR has positive nutritional features as it is rich in dietary fiber, polyphenols, and lipids which are available in good amounts in the bran layer of caryopsis [ 10 ]. Compared to BR, white rice has a poorer nutritional value as, during milling, removal of bran and germ diminishes fiber, vitamins and minerals as well as protein content [ 11 ]. Thus, the utilization of BR in RTE foods could be a good strategy to increase not only its nutritional value but also take out the burden of long cooking time [ 12 ].

A popular technology to produce RTE cereal products is sterilization in pouches. However, when this intense thermal treatment is performed on white rice grain, its integrity is lost resulting in a sticky product with a soft texture. A potential solution to produce rice-based RTE aseptic products is the utilization of BR. The long cooking time of BR is a positive feature for aseptic processing since it allows to sterilize the product with limited effects on grain structural integrity. Aseptic processing also removes the need for long cooking by the consumer, which is a barrier for BR consumption. Furthermore, the use of BR, instead of white rice, as the main ingredient in these highly processed foods, which are potentially associated with poor dietary quality and obesity [ 13 ], could greatly improve their nutritional value. Fiber, minerals and proteins present in BR are not lost during the cooking-sterilization process in an enclosed pouch, and bioactive compounds present in rice bran are more available after being thermally treated [ 14 ]. Finally, BR rice contains a higher amount of bioactive lipids and flavonoids than white rice [ 15 ] which may further support the human immune system also against COVID-19 [ 16 ]. All these characteristics make BR an optimal candidate for the design of RTE BR-based functional foods. Such RTE products could be a mean to contribute significantly to increase the consumption of BR and to help consumers in familiarizing with the consumption of whole-meal foods [ 6 ].

To the authors’ best knowledge, no information is available in the literature on the optimization of RTE BR cooking process in pouches, and on the characterization of its shelf-life stability. In this study, cooking conditions of BR have been optimized at first, and then, the effect of hydration level and storage time on main quality attributes (e.g. texture and color) of RTE BR have been evaluated.

Materials and methods

Brown rice optimal cooking time determination.

BR of Roma variety has been gently provided by a local producer (Grandi Riso S.p.A., Codigoro, Ferrara, Italy). Rice was cooked in boiling water (1:20, rice:water) in a pot for variable lengths of time (10, 15, 20, 25, 30, 35, 40 and 45 min). BR and cooking water were separated by draining rice with a colander and cooled down to room temperature for 30 min before further analysis. The minimum cooking time to consider BR cooked was calculated through the determination of the point of inflection of the rice moisture absorption curve [ 17 ]. All the experiments were carried out at the Department of Food and Drug, University of Parma (Italy).

Brown rice moisture content

The moisture content of BR at variable cooking times was evaluated by drying in an air forced oven at 105 °C to constant weight according to AACCI method 44-15.02. The analysis was performed in triplicate for each cooking time.

Brown rice texture

Texture profile analysis (TPA) was performed on rice samples using a Texture Analyzer (Stable Micro Systems, Godalming, UK) equipped with a 25 kg load cell and an aluminum cylinder probe with a diameter of 40 mm, following Boluda-Aguilar et al. [ 2 ] with some modification. A test speed of 0.1 mm/sec and a total strain of 75% were used. Three g of rice was spread in single layer grain on the instrument base. Three replicates were performed on each sample. Textural attributes considered were: hardness (N, maximum force of the first compression) and stickiness (N.cm −1 , negative area after the first compression) [ 18 ].

Brown rice grain morphology

Forty BR kernels were arranged in a thin layer on a transparent plastic sheet. A dimensional reference was added to determine pixel:mm ratio of every image. BR pictures were acquired using a scanner (HP Scanjet 8200) with a resolution of 600 pixel and analyzed with the software ImageJ [ 19 ]. Acquired images were then converted in black and white and threshold adjusted before measuring the averaged area, solidity, and circularity of rice kernels.

Brown rice cooking loss

Cooking loss, defined as the amount of solids lost into the cooking water, was determined according to the AACC official method 16–50.

RTE brown rice poches production and microbial safety assessment

RTE BR pouches were produced by a local producer. BR was washed, inserted into a pouch (250 g, composite packaging, 406,735, Goglio Packaging System, Milan, Italy) together with enough tap water to reach theoretical total moisture contents of 54, 57, and 60 g water/100 g product. Pouches were then hermetically sealed, placed vertically into baskets that were then inserted into a horizontal autoclave, which was first filled with water at 85 °C, heated to 118 °C and held for 35 min. The cooking-sterilization process was static, not allowing for pouches rotation. At the end of the thermal treatment, pouches were cooled down, unloaded, and stored at room temperature to reproduce domestic preservation conditions. One pouch was open for every point of shelf life at the following times: 0, 40, 80, 120, 160, 270, and 365 days. For every storage time, microbiological analysis was performed to assess the sterility of the product. Aliquot of samples were homogenized 1:10 (Seward Stomacher, 400 circulator, UK) with sterile Ringer solution (Oxoid, Basingstoke, UK), tenfold diluted and plated in duplicate on different culture media. Total mesophilic and spore-forming mesophilic bacteria were determined on Plate Count Agar (PCA) (Oxoid, Basingstoke, UK) after incubation at 30 °C for 48 h. Yeast and molds were grown on Yeast Extract Dextrose Chloramphenicol Agar (YEDC) (REMEL Lenexa, USA) after incubation at 25 °C for 72–120 h. Brilliance™ Bacillus cereus Agar Base supplemented with Brilliance ™ Bacillus cereus selective supplement (Oxoid, Basingstoke, UK) and incubated at 37 °C for 48 h was used to enumerate Bacillus cereus . Regarding spore-forming bacteria, first dilution of the samples was treated at 85 °C for 15 min before plate counts. Analyses were carried out in duplicate and for each sampling time average values ± standard deviations were reported as UFC/g.

Water spatial distribution in pouches

Brown rice moisture content homogeneity throughout the pouch was assessed by means of its moisture content, by extracting rice samples from 24 different locations in the pouch. Sampling locations were equally distanced to assure homogeneous distribution of sampling points through the pouch. Moisture content was then determined as described in 2.1.1. Moisture spatial distribution was measured in three pouches per each BR moisture content.

Brown rice color in pouches

Color was measured on the surface of cooked BR using a Minolta Colorimeter (CM 2600d, Minolta Co., Osaka Japan) in the 400–700 nm range using illuminant D65 and for a 2° position of the standard observer. L* (lightness), a ∗ (redness), b ∗ (yellowness) were measured for at least ten measurements at each cooking time and each shelf-life time. ΔE was calculated according to Eq. 1 , taking the color of rice cooked at time 0 as reference.

Brown rice texture in pouches

Each BR pouch was massaged to un-grain and mix their content prior to be opened to extract BR samples (80 g). Samples were transferred into a closed container and heated in a microwave for 1 min at 900 W, to replicate a standard heating procedure the product would undergo prior to consumption. Heated rice was allowed to cool down to room temperature prior to texture profile analysis (TPA) that was performed as described in “ Brown rice texture ”.

Statistical analysis

Data are presented as average ± standard deviation. At least three replicates were performed for each analysis. Significant differences ( p ≤ 0.05) among samples were calculated by multivariate analysis of variance (MANOVA) with a Tukey-high significant difference test. SAS 9.4 (SAS institute corporation, NC, USA) was used to perform the statistical analysis.

Results and discussion

The cooking process of BR in excess water was studied with respect to water uptake and textural changes occurring in rice kernels for different lengths of time. This preliminary study was carried out to determine the amount of water needed to reach optimal cooking of BR, and therefore to design conditions to achieve optimal cooking of BR within sealed pouches. Optimal cooking time has been reported to correspond with the point at which most of the starch present in the kernel is gelatinized, condition that can be determined with the inflection point of a moisture absorption kinetic curve [ 17 ]

Appearance of BR after cooking for different times is shown in Fig. 1 . BR kernels cooked up to 20 min were characterized by a smooth surface and retained their original shape and structural integrity. At 25 min cooking, BR kernels started to break due to moisture absorption and volume expansion indicative of an important amount of gelatinized starch. The number of broken kernels increased with cooking time and their shape become progressively more irregular. After 45 min, an important amount of starch leached out from the kernels, as it was observable by the presence of a large quantity of material collecting on the plastic sheet used to arrange the sample for image acquisition. BR kernels area was measured as a function of cooking time (Table 1 ), and it was found to progressively increase from 20.9 ± 2.7 to 25.3 ± 3.7 mm 2 with cooking time increase from 10 to 25 min. Rice kernels expansion is due, primarily, to water absorption, the consequent swelling, and gelatinization of starch granules during cooking. However, after 25 min of cooking, even though rice kept absorbing water, its area increased at a slower pace, suggesting that rice starch had reached its maximum swelling ability and was not able to further expand [ 20 ]. At longer cooking times, BR kernels underwent breakage and disruption decreased their solidity, circularity and slightly, but nor significantly, increased their overall area (Table 1 ).

Appearance of brown rice kernels after cooking in a pot for different lengths of time

Water uptake in BR during cooking was monitored and it was found, as expected, to increase with increasing cooking time (Fig. 2 ). Moisture content of BR gradually increased from 38.0 ± 0.2 to 52.9 ± 0.8 g water/100 g product up to 25 min cooking. At longer cooking times, water absorption still occurred but at a slower rate, reaching a maximum of 64.9 ± 0.2 g water/100 g product at 45 min cooking. From the data reported in Fig. 2 , it is possible to observe the occurrence of an inflection after 25 min of cooking, leading to the identification of 25 min as the minimum cooking time at which the rice could be considered cooked in excess boiling water [ 17 ]. Solid loss from BR kernels increased exponentially with increasing cooking time, as measured by the increase in turbidity of the cooking water (Fig. 2 ), resulting from solids (primarily amylose and short-chain amylopectin) lost in cooking water [ 21 ]. At the initial stages of cooking, turbidity grew slowly due to the limited starch gelatinization with few broken starch granules and the presence of intact husks that protected and retained the starchy endosperm within the kernel. Increasing cooking times lead to more extensive gelatinization and an increasing number of kernels showing damaged husks, resulting in an increased release of solids.

Changes in physico-chemical attributes of brown rice (moisture content, kernel area, hardness) and cooking water (turbidity) during cooking. Gray area represents the range of acceptable cooking conditions

Textural attributes of BR significantly changed upon cooking due to water absorption and structural changes occurring in rice constituents, primarily associated with starch gelatinization. BR hardness was very high at the beginning of the cooking process, 255.1 ± 11.6 N after 10 min of cooking, and gradually decreased, as expected, to 56.4 ± 6.8 N after 45 min of cooking. Hardness decrease could be divided into two phases reflecting the trend observed for moisture uptake. A first phase, characterized by a rapid decrease in hardness, was observed until 25 min of cooking, and a slower decrease for further cooking from 25 to 45 min.

Studies on the degree of starch gelatinization at variable cooking times in pasta [ 22 ] indicated that only 80% of starch was gelatinized at the cooking time suggested by the pasta producer, while 90% starch gelatinization was reached only in an overcooked product. In this respect, a complete starch gelatinization is not required to consider a product cooked [ 23 ]. Therefore, we can expect starch to be mainly gelatinized in BR at the inflection point where water uptake is reduced, but it can be considered cooked over a larger range of moisture contents.

In this work, the extremes of BR cooking were set, for the lower limit, in correspondence of the inflection point of the moisture uptake curve (25 min, corresponding to a reduction of water uptake), and for the higher limit, at 35 min. The value of 35 min was selected because it corresponded to a condition where kernel damage was still contained. This statement was supported by limited turbidity of the cooking water (593 NTU) and BR kernel high stickiness (8.4 ± 2.1 N cm −1 ) as compared to 1082 NTU and 4.2 ± 0.8 N cm −1 , respectively, at 40 min cooking, indicating a shift of solids from BR kernel surface into the cooking water. The moisture content of rice at the lower (25 min) and higher (35 min) end of the cooking range were 52.9% ± 0.8 and 59.9% ± 1.0, respectively. Based on the results obtained, the moisture contents to cook rice in pouches were designed to be 54, 57 and 60%.

RTE brown rice in pouches: characterization and long-term shelf-life stability

Moisture content and spatial distribution in pouches.

Rice was cooked in pouches with the theoretical amount of water to reach the minimal amount of moisture necessary to cook the rice. Total mesophilic bacteria, spore-forming bacteria, yeasts and molds and B. cereus were not present above the detection limit (10 UFC/g) throughout the shelf life considered, confirming the efficacy of the treatment. At the end of aseptic processing, which was carried out in a static manner, the real moisture content of rice was determined. The average moisture content of BR in the pouches was 53.9% ± 3.8, 57.1% ± 0.7 and 60.3% ± 0.5 and well approximated the theoretical target moisture contents (54%, 57%, and 60% moisture content, respectively). The averaged moisture content of all samples remained constant for the duration of the storage time (1 year).

Water content in different locations of the pouches was measured to verify homogeneity of the cooking process inside pouches to ensure the product’s uniformity. Water distribution was not homogenous in the 54% moisture pouch, while it was evenly distributed throughout the sample in other pouches (57 and 60%), as shown in Fig. 3 . BR in the 54% moisture pouch had a higher moisture content at the top and a lower at the bottom of the pouch (Fig. 3 ). This can be explained by the dynamics of the cooking process in a confined environment (pouch); upon heating, water turns into vapor and moves towards the upper zone of the pouch, creating a dis-uniform distribution of water that is particularly relevant in the lower moisture product. An uneven water distribution causes a different degree of water penetration into rice kernel and, consequently, uneven cooking of the product. Water availability affects starch gelatinization temperature [ 24 ]. Therefore, different moisture levels can also affect starch gelatinization. BR at 54% moisture had limited available water, leaving some rice kernels, located in the lower part of the pouch, underhydrated and not able to gelatinize under the processing conditions. This resulted in uncooked rice kernels with a more vitreous aspect. Therefore, we can conclude that 54% moisture is not enough to homogeneously cook BR in pouches. On the contrary, in the pouches with 57% and 60%, the amount of moisture was enough to cook the rice evenly within the pouch ensuring homogeneous water distribution and rice grain textural attributes. These data showed that the cooking dynamic of BR in a pot and within a pouch is different and that particular care must be taken in defining the optimal moisture content of a product to ensure proper cooking of the entire pouch content and its sterilization.

Moisture content of brown rice as a function of spatial distribution in pouches with different theoretical moisture contents

Texture analysis

Hardness and stickiness of BR after re-heating in a microwave oven are shown in Table 2 . Hardness and stickiness were measured as they are the most important textural attributes that affect consumer acceptability in rice [ 25 ]. As expected, water content was found to be the most important factor affecting BR hardness, with rice kernels becoming softer with increasing moisture content, as shown in Table 2 . Average values of hardness resulted comparable to BR with a similar amount of moisture cooked in a pot, as shown in Fig. 2 . The storage time had a significant effect on BR hardness up to 1-year shelf life. Indeed, BR hardness decreased with increasing storage time until 120 days in all samples, and then increased at longer storage times. This trend in hardness suggests the occurrence of different events at short and long storage times and is likely related to starch structural conformation and its interaction with water. It is well known that gelatinized starch is subjected to amylopectin retrogradation and staling during storage, resulting in increase of hardness [ 26 ]. However, as previously observed [ 27 ] heating of BR in a microwave oven prior to analysis had a partial effect on reducing amylopectin retrogradation and conferred a fresh-like consistency to the product. It is possible that at longer storage times amylopectin undergoes modification that are not reversible with the microwave treatment used to warm rice. Amylopectin modification could have limited interaction between starch and water leading to decreased chain flexibility affecting gel-like texture. Further investigation at a molecular level will be necessary to better understand changes in the hardness of rice during shelf life.

Stickiness of BR was found to increase with increasing moisture level and storage time, as shown in Table 2 . Both water ( p < 0.0001) and time ( p < 0.0001) had a significant effect on the stickiness of rice, however, the effect of water was predominant. Rice stickiness has been correlated with its content in amylose and protein [ 28 ]. When rice is cooked in a pot, the ratio between water to rice affects stickiness between granules, with an increase of stickiness with increasing water [ 29 ] suggesting that high leaching of starch consequent to high water content affected BR stickiness. In the native starch granules, small amylopectin molecules may entangle with large amylopectin molecules by non-covalent bonding or co-crystallize with other large amylopectin molecules, at the edges of blocklets, and are free to leach once the crystalline structure is destroyed by heating [ 30 ]. An increased degree of BR cooking can result in a higher disruption of the starch granules [ 31 ] which can lead to a larger leaching of starchy components and to a consequent increase in stickiness. Higher amount of moisture might have favored amylopectin and amylose leaching, resulting in a stickier product. H bonding between larger amylopectin and other amylopectin molecules is at the base of rice stickiness [ 30 ]. Thus, higher moisture levels might have favored greater interactions among amylopectin chains, generating a denser network of H bonds and therefore leading to higher stickiness. In this study, it was not possible to make a comparison of stickiness between BR in pouch and that in pot since a small quantity of oil was added to the pouches to reduce the adhesion among kernels during cooking.

Color of BR (L, a*, b* and Δ E , Table 3 ) was found to be significantly affected by moisture content. Increasing moisture resulted in an increased L ( p < 0.0001), and decreasing a* ( p = 0.0033), while b* did not change significantly. These results confirm the findings of Lamberts et al. [ 32 ] but are in contrast with a previous study on BR hydration that shows decreasing levels of L at higher levels of hydration [ 33 ].

No significant effects of time were found on L and a*. On the other hand, a significant effect was observed for the values of b* with an increase in storage time leading to a lower level of b*. Furthermore, Δ E values indicate that the difference in color during the shelf life are perceptible after 40 days of storage by an untrained eye, showing values larger than 2 [ 34 ]. Pigment migration diffused from the bran into the endosperm can potentially explain the change in color during shelf life [ 32 ], or occurrence of oxidative process into the pouch altering the color of rice might be speculated. Further research will be necessary to determine what are the changes leading to decrease in yellowness in rice.

Brown rice could be a valuable ingredient in RTE meals, but the right hydration level needs to be optimized. This information was acquired using a step-by-step decision approach. Firstly, BR physiochemical properties at different hydration levels has been assessed at lab scale. From lab-scale experiments, three different hydration levels were selected and applyed for BR cooking in pouches in a pilot plant facility. It was found that, when a low moisture content (54%) identified at lab scale, was applied in the pouch, rice was not homogeneously cooked demonstrating different cooking dynamic in different environments. Conversely, higher moisture contents resulted in uniform cooking of rice kernels without affecting its microbial safety. Significant changes in texture and color were observed in brown rice during 1-year storage time, mainly related to moisture and storage time. Samples became less hard up to 120-day storage, conversely, prolonging shelf-life led to increases in hardness that might affect the product acceptability. However, further investigation will be required to better understand the cause of the physiochemical changes during shelf life of RTE pouches. A greater understanding of the textural changes in brown rice during shelf life will potentially allow to formulate new strategies to mitigate them and to successfully employ this disregarded, but nutritionally valuable ingredient, in producing RTE meals.

Gehlhar M, Regmi A (2005) Factors shaping global food markets. New directions in global food markets, 1:5–17

Shahbaz M, Bilal M, Moiz A, Zubair S, Iqbal H (2020) Food safety and COVID-19: precautionary measures to limit the spread of coronavirus at food service and retail sector. J Pure Appl Microbiol 14(suppl 1):749–756

Article CAS Google Scholar

Nguyen TH, Vu DC (2020) Food delivery service during social distancing: proactively preventing or potentially spreading coronavirus disease–2019? Disaster Med Public Health Prep 14(3):e9–e10

Article Google Scholar

Boluda-Aguilar M, Taboada-Rodríguez A, López-Gómez A, Marín-Iniesta F, Barbosa-Cánovas GV (2013) Quick cooking rice by high hydrostatic pressure processing. LWT-Food Sci Technol 51(1):196–204

Considerations for Community-Based Organizations. Center for disease control and prevention. https://www.cdc.gov/coronavirus/2019-ncov/community/organizations/community-based.html#:~:text=There%20is%20no%20evidence%20that,family%2Dstyle%20meal . Feb 2021

Mohan V, Ruchi V, Gayathri R, Bai MR, Shobana S, Anjana R, Unnikrishnan R, Sudha V (2017) Hurdles in brown rice consumption. In: Manickavasagan A, Santhakumar C, Venkatachalapathy N (eds) brown rice. Springer, pp 255–269

Chapter Google Scholar

Gujral HS, Kumar V (2003) Effect of accelerated aging on the physicochemical and textural properties of brown and milled rice. J Food Eng 59(2–3):117–121

Xia Q, Green BD, Zhu Z, Li Y, Gharibzahedi SMT, Roohinejad S, Barba FJ (2019) Innovative processing techniques for altering the physicochemical properties of wholegrain brown rice ( Oryza sativa L.)–opportunities for enhancing food quality and health attributes. Crit Rev Food Sci Nutr 59(20):3349–3370

Mir SA, Bosco SJD, Shah MA (2019) Technological and nutritional properties of gluten-free snacks based on brown rice and chestnut flour. J Saudi Soc Agric Sci 18(1):89–94

Google Scholar

Shobana S, Malleshi N, Sudha V, Spiegelman D, Hong B, Hu F, Willett W, Krishnaswamy K, Mohan V (2011) Nutritional and sensory profile of two Indian rice varieties with different degrees of polishing. Int J Food Sci Nutr 62(8):800–810

Babu PD, Subhasree R, Bhakyaraj R, Vidhyalakshmi R (2009) Brown rice-beyond the color reviving a lost health food-a review. American-Eurasian J Agron 2(2):67–72

Mir SA, Shah MA, Bosco SJD, Sunooj KV, Farooq S (2020) A review on nutritional properties, shelf life, health aspects, and consumption of brown rice in comparison with white rice. Cereal Chem 97(5):5–13

Monteiro CA, Levy RB, Claro RM, de Castro IRR, Cannon G (2010) Increasing consumption of ultra-processed foods and likely impact on human health: evidence from Brazil. Public Health Nutr 14(1):5–13

Kim S-M, Chung H-J, Lim S-T (2014) Effect of various heat treatments on rancidity and some bioactive compounds of rice bran. J Cereal Sci 60(1):243–248

Liu L, Guo J, Zhang R, Wei Z, Deng Y, Guo J, Zhang M (2015) Effect of degree of milling on phenolic profiles and cellular antioxidant activity of whole brown rice. Food Chem 185:318–325

Galanakis CM (2020) The food systems in the era of the coronavirus (COVID-19) pandemic crisis. Foods 9(4):523

Billiris M, Siebenmorgen T, Meullenet J-F, Mauromoustakos A (2012) Rice degree of milling effects on hydration, texture, sensory and energy characteristics. Part 1. Cooking using excess water. J Food Eng 113(4):559–568

Peleg M (1976) Texture profile analysis parameters obtained by an Instron universal testing machine. J Food Sci 41(3):721–722

Abràmoff MD, Magalhães PJ, Ram SJ (2004) Image processing with Image. J Biophotonics Int 11(7):36–42

Vidal V, Pons B, Brunnschweiler J, Handschin S, Rouau X, Mestres C (2007) Cooking behavior of rice in relation to kernel physicochemical and structural properties. J Agric Food Chem 55(2):336–346

Yang L, Sun Y-H, Liu Y, Mao Q, You L-X, Hou J-M, Ashraf MA (2016) Effects of leached amylose and amylopectin in rice cooking liquidon texture and structure of cooked rice. Braz Arch Biol Technol. https://doi.org/10.1590/1678-4324-2016160504

Littardi P, Diantom A, Carini E, Curti E, Boukid F, Vodovotz Y, Vittadini E (2019) A multi-scale characterisation of the durum wheat pasta cooking process. Int J Food Sci Technol 54(5):1713–1719

Schirmer M, Jekle M, Becker T (2015) Starch gelatinization and its complexity for analysis. Starch-Stärke 67(1–2):30–41

Eliasson AC (1980) Effect of water content on the gelatinization of wheat starch. Starch-Stärke 32(8):270–272

Li H, Gilbert RG (2018) Starch molecular structure: the basis for an improved understanding of cooked rice texture. Carbohydr Polym 195:9–17. https://doi.org/10.1016/j.carbpol.2018.04.065

Article CAS PubMed Google Scholar

Li H, Gilbert RG (2018) Starch molecular structure: The basis for an improved understanding of cooked rice texture. Carbohydr Polym. https://doi.org/10.1016/j.carbpol.2018.04.065

Article PubMed Google Scholar

Mandala I (2005) Physical properties of fresh and frozen stored, microwave-reheated breads, containing hydrocolloids. J Food Eng 66(3):291–300

Hamaker B, Griffin V, Moldenhauer K (1991) Potential influence of a starch granule-associated protein on cooked rice stickiness. J Food Sci 56(5):1327–1329

Bett-Garber KL, Champagne ET, Ingram DA, McClung AM (2007) Influence of water-to-rice ratio on cooked rice flavor and texture. Cereal Chem 84(6):614–619. https://doi.org/10.1094/Cchem-84-6-0614

Li H, Fitzgerald MA, Prakash S, Nicholson TM, Gilbert RG (2017) The molecular structural features controlling stickiness in cooked rice, a major palatability determinant. Sci Rep 7:43713. https://doi.org/10.1038/srep43713

Article PubMed PubMed Central Google Scholar

Shamekh S, Forssell P, Suortti T, Autio K, Poutanen K (1999) Fragmentation of oat and barley starch granules during heating. J Cereal Sci 30(2):173–182

Lamberts L, De Bie E, Derycke V, Veraverbeke W, De Man W, Delcour J (2006) Effect of processing conditions on color change of brown and milled parboiled rice. Cereal Chem 83(1):80–85

Oli P, Ward R, Adhikari B, Torley P (2016) Colour change in rice during hydration: effect of hull and bran layers. J Food Eng 173:49–58

Mokrzycki W, Tatol M (2011) Colour difference∆ E-A survey. Mach Graph Vis 20(4):383–411

Download references

Acknowledgements

The authors would like to thank Mr. Gianni De Cecchi for producing the aseptic rice pouches.

Research was partially funded by Grandi Riso S.p.A.

Author information

Authors and affiliations.

Food and Drug Department, University of Parma, Parco Area Delle Scienze, 49/A, 43124, Parma, Italy

Enrico Federici, Valentina Gentilucci & Valentina Bernini

Department of Food Science, Purdue University, West Lafayette, IN, 47907, USA

Enrico Federici

School of Biosciences and Veterinary Medicine, University of Camerino, via Gentile III da Varano 3, 62032, Camerino, MC, Italy

Elena Vittadini

Department of Agricultural, Food, Environmental and Animal Sciences, University of Udine, via Sondrio 2/A, 33100, Udine, Italy

Nicoletta Pellegrini

You can also search for this author in PubMed Google Scholar

Contributions

Authors NP, EV, VB contributed to the study conception and design. Material preparation, data collection and analysis were performed by EF, VG. The first draft of the manuscript was written by EF and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Corresponding author

Correspondence to Elena Vittadini .

Ethics declarations

Conflict of interest.

The authors have no relevant financial or non-financial interests to disclose.

Compliance with ethics requirements

This article does not contain any studies with human or animal subjects performed by the any of the authors.

Additional information

Publisher's note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and permissions

About this article

Federici, E., Gentilucci, V., Bernini, V. et al. Ready to eat shelf-stable brown rice in pouches: effect of moisture content on product’s quality and stability. Eur Food Res Technol 247 , 2677–2685 (2021). https://doi.org/10.1007/s00217-021-03790-2

Download citation

Received : 23 February 2021

Revised : 25 May 2021

Accepted : 29 May 2021

Published : 15 September 2021

Issue Date : November 2021

DOI : https://doi.org/10.1007/s00217-021-03790-2

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Ready to eat
Rice texture
Find a journal
Publish with us
Track your research

Review article
Open access
Published: 21 October 2019

Nutritional and functional properties of coloured rice varieties of South India: a review

Rathna Priya T. S. 1 ,
Ann Raeboline Lincy Eliazer Nelson 1 ,
Kavitha Ravichandran 1 &
Usha Antony 1

Journal of Ethnic Foods volume 6 , Article number: 11 ( 2019 ) Cite this article

72k Accesses

119 Citations

139 Altmetric

Metrics details

Rice is a major cereal food crop and staple food in most of the developing countries. India stands second in the production of rice next to China. Though almost 40,000 varieties of rice are said to exist, at present, only a few varieties are cultivated extensively, milled and polished. Even if white rice is consumed by most people around the world, some specialty rice cultivars are also grown. These include the coloured and aromatic rice varieties. The nutritional profile of the specialty rice is high when compared to the white rice varieties. The coloured rice, which usually gets its colour due to the deposition of anthocyanin pigments in the bran layer of the grain, is rich in phytochemicals and antioxidants. Rice bran, a by-product of the rice milling industry is under-utilised, is rich in dietary fibre which finds application in the development of functional foods and various other value-added products. Thus, more focus on specialty rice and its by-products will not only save it from becoming extinct but also lead a step forward towards nutrition security of the country as they are abundant in vitamins, minerals and polyphenols.

Introduction

Rice is a major cereal crop consumed as a staple food by over half of the world’s population. Consumption of rice is very high in developing countries and nations in Asia. Almost 95% of the rice production is done in Asian countries and about half of the world’s population consumes it. The cultivation of rice ranks third in the production of agricultural commodity next to sugarcane and maize. It is the predominant dietary energy source of 17 countries in Asia and the Pacific, 9 countries in North and South America and 8 countries in Africa. India is one of the major centres for rice production. The area for rice cultivation in India comprises about 43,388,000 hectares of land [ 1 ] and rice contributes to 780 and 689 kcal/capita/day of the food supply in Asia and India, respectively. Furthermore, India is one of the largest countries in terms of energy consumption from agriculture and rice comprises a major part of it [ 2 ].

Rice is rich in genetic diversity, with thousands of varieties grown throughout the world and India is home to 6000 varieties, at present. Originally, India had more than 110,000 varieties of rice until 1970, which were lost during the Green Revolution with its emphasis on monoculture and hybrid crops [ 3 ]. Paddy comes in many different colours, including brown, red, purple and even black. The colourful varieties of rice are considered valuable for their health benefits. The unpolished rice with its bran has high nutrient content than milled or polished white rice. However, rice consumers prefer to consume polished white rice, despite the fact that brown rice contains valuable nutrient content [ 4 ]. A detailed analysis on the nutrient content of rice suggests that the nutrition value varies depending upon several factors such as the strain or variety (i.e. white , brown , red and black /purple), nutrient quality of the soil in which rice is cultivated, the degree of milling and the method of preparation before consumption.

Origin and spread of rice

Oryza sativa , the dominant rice species, is a member of the Poaceae family. Historically, rice was cultivated widely in the river valleys of South and Southeast Asia 10,000 years ago [ 5 ] and it is believed to have originated probably in India. Domestication of rice in India is mainly attributed to the Indus valley civilization c. 3000–1500 BC [ 6 ]; however, the evidence of rice cultivation in India has been pushed to 4000 years ahead with the discovery of rice grains and early pottery found in the site of Lahuradewa, Uttar Pradesh, situated in the middle Ganges plains dating to c. 6409 BC [ 7 , 8 ].

Rice is highly adaptable to its environment of growth and this is evident from the fact that it is grown in north-eastern parts of China at latitude 53°N, on the equator in central Sumatra, and at 35°S in New South Wales, Australia. In India, it is grown below sea level in Kerala; most rice-growing areas are present at or near sea level and also, at elevations above 2000 m in Kashmir. Today, rice is cultivated in all parts of the world except Antarctica [ 9 ].

Importance of rice in India

India ranks second in the production of rice in the world next to China, accounting for 22.5% of overall world rice production. Rice is India’s pre-eminent crop and is the staple food of the people of the eastern and southern parts of the country. Apart from being nutritionally rich, rice has greater significance in India and holds great spiritual and ritual importance. As per Indian tradition, rice is revered as a potent symbol of auspiciousness, prosperity and fertility because of its life-sustaining qualities. Several rituals involving rice are performed during different occasions and festivals. In Tamil Nadu, kolam , a kind of geometric pattern, is drawn using rice flour at the threshold of the houses by women before sunrise. Rice also plays a vital role in wedding ceremonies in India. Dhanpan is a ritual wherein the family of bridegroom sends paddy, betel and/or turmeric to the house of the bride [ 10 ]. Rice mixed with turmeric is thrown on the couples during the wedding ceremony as a symbol of prosperity, eternity, continuity and fertility. The father of the bride organises a feast called Bhat (means, boiled rice) for the family and relations of the bridegroom [ 10 ]. The brides throw five handfuls of rice before leaving their parents’ home after the wedding to wish prosperity and wealth and remain with the family members. The bride enters her new home by pushing a glass or a jar full of rice while, rice is the first food offered to the bridegroom by the bride after marriage. In Tamil Nadu, the groom is offered a special variety of rice named Maappillai Samba to improve fertility [ 11 ]. Rice also plays a vital role during the baby shower function, named godh bharai in North India, valaikaapu in Tamil Nadu and seemandham in Kerala; on the event of birth; at the time of giving first solid food to the baby that is 6 or 7 months old; and during puberty in Kerala and Tamil Nadu. Flattened rice made from a variety called Thavala Kannan is given as offering in Kerala.

Rice also plays a prominent role in cultural celebrations of India, such as the festivals are based on sowing of seeds in the paddy field, transplanting the saplings in the fields, removal of weeds from the fields, harvesting of paddy, thrashing of paddy and storage of paddy [ 10 ]. The harvest festivals include Thai Pongal celebrated in the Tamizhian calendar month of Thai (falls in the month of January) in Tamil Nadu; Onam celebrated in the Malayalam month of Chingam (falls in the month of August or September) and Sankranti in Andhra Pradesh and Telangana, Makar Sankranti in Karnataka, Na-Khuwa Bhooj in rural Assam, Nabanna in West Bengal, and Nua khia or Navanna in Odisha; and Bihu in Assam celebrates the harvest of paddy. Thus, rice has not only shaped the history, culture, diet and economy of people but also the growth stage of the rice crop marks the passage of time and season. In India, rice is considered the root of civilization [ 12 ].

Production and market demand for rice varieties

Rice is a fundamental food in many cultural cuisines around the world. According to Ricepedia, more than 90% of production and consumption of rice in the world occur in Asia and the current share in global rice consumption is around 87%. In African countries, per capita consumption continues to increase than production [ 13 ]. The volume of international rice trade has increased almost sixfold, from 7.5 million tonnes annually in the 1960s to an average of 44.2 million tonnes during 2015–2016.

Based on the global market scenario with respect to rice, the production has increased slightly with years. The use of rice as food remains predominant compared to feed and other uses. The supply and utilisation of rice have also increased slightly (Table 1 ).

Similarly, rice is a major cereal crop and is consumed as a staple food by the majority of the population in India. India is one of the major centres for the production of rice. Both the Himalayan red rice and the Assam red rice find their place in international trade. The production of rice, wheat and maize has grown steadily over this period and that of rice is the highest followed by wheat (Table 2 ). In contrast, the production of other grains such as sorghum, pearl millet, finger millet, little millet and coarse cereals have either remained steady or have declined.

Rice is consumed by the rich and poor as well as rural and urban households. The per capita net availability of food grains increased after the Green Revolution, and rice is a part of the balanced diet along with vegetables, pulses, eggs, meat and fruits. The per capita net availability of rice increased to 69.3 kg/year in 2017 from 58.0 kg/year in 1951 [ 15 , 16 ]. Although rice is widely consumed, with years, the expenditure on cereals decreased from 26.3% in 1987–1988 to 12.0% in 2011–2012 and from 15% in 1987–1988 to 7.3% in 2011–2012 in rural and urban households, respectively. This overall dip in the expenditure may be due to the fact that more money is spent on non-food items in both rural and urban households [ 16 ].

Rice varieties

Among the 40,000 varieties of rice cultivated worldwide, only two major species are cultivated widely— Oryza sativa or the Asian rice and Oryza glaberrima or the African rice. The cultivation of Oryza sativa is practised worldwide; however, the cultivation of the Oryza glaberrima is confined to Africa [ 17 ].

Oryza sativa has two major subspecies: the Indica , long-grain rice and the Japonica , round-grain rice. Japonica rice is mainly cultivated and consumed in Australia, China, Taiwan, Korea, the European Union, Japan, Russia, Turkey and the USA. Indica rice varieties are grown widely in Asia [ 17 ]. These varieties also comprise of the fragrant ones which are priced as premium. The principal fragrant varieties are Hom Mali from Thailand and the various types of Basmati exclusively grown on the Himalayan foothills of India (in the states of Haryana and Punjab) and Pakistan (in the state of Punjab) [ 18 ].

The Indian rice varieties cultivated widely are Basmati , Joha , Jyothi , Navara , Ponni , Pusa , Sona Masuri , Jaya , Kalajiri (aromatic), Boli , Palakkad Matta , etc. The coloured variety includes Himalayan red rice; Matta rice, Kattamodon , Kairali , Jyothy , Bhadra , Asha , Rakthashali of Kerala; Red Kavuni , Kaivara Samba , Mappillai Samba , Kuruvi Kar , Poongar of Tamil Nadu, etc.

The shelf life of rice

In general, it is recommended to store rice in the form of paddy rather than as milled rice, since the husk provides protection against insects and helps prevent quality deterioration. Rice can be stored for long periods only if the following three conditions are met and maintained: (1) the moisture levels of grains, 14% or less and that of seeds must be 12% or less; (2) grains must be well protected from insects, birds and rodents; and (3) grains must be protected from rains or imbibing moisture from the atmosphere. In addition to its nutritive and medicinal properties, red rice and black rice possess several other special features and the most common one is their resistance to insects and pests during storage than brown rice. From the cultivation point of view, red rice possesses resistance to drought, flood, submergence, alkalinity, salinity, and resistance to pests and diseases [ 19 ].

Structure of rice grain

The paddy (also, rough rice or rice grain) consists of the hull, an outer protective covering, and the fruit or rice caryopsis (brown or dehusked rice) [ 20 ]. Rice primarily consists of carbohydrates, proteins and small quantities of fat, ash, fibre and moisture. Vitamins and minerals are largely confined to the bran and germ [ 21 ].

The polished white rice, usually consumed, is the highly refined version of raw rice. The processing and milling of raw rice take away significant parts of the grain, namely the bran and the germ. Both bran and germ are rich in dietary fibre as well as nutrients that are beneficial for human health. Further, if white rice undergoes additional polishing, its aleurone layer getsremoved leading to loss of more nutrients, as this layer is rich in vitamin B, proteins, minerals and essential fats.

In this aspect, the coloured rice finds an advantage as a healthier alternative to white rice. Coloured rice varieties and brown rice varieties have the same harvesting process apart from possessing similar nutritional profiles. These varieties are usually either dehulled or partially hulled with the bran and germ intact. Brown rice is found worldwide, while red rice is confined to the Himalayas, Southern Tibet, and Bhutan, as well as parts of North East and South India. After the removal of husk, brown rice still consists of few outer layers—the pericarp, seed-coat and nucellus; the germ or embryo; and the endosperm. The endosperm consists of the aleurone layer, the sub-aleurone layer and the starchy or inner endosperm (Fig. 1 ). The aleurone layer encloses the embryo. Pigments are confined to the pericarp layer [ 20 ].

Structure of rice grain (Copyright: FAO) [ 22 ]. Paddy consists of the husk, bran, aleurone layer, starchy endosperm and embryo. Brown rice is semi-polished, so it retains embryo while white rice is more polished than brown rice, lacking bran, aleurone and embryo. The removal of bran, aleurone and embryo provides aesthetic appeal to rice and improves shelf life; however, it also removes nutrients and minerals found in the grain

The hull (also, husk) constitutes about 20% of the rough rice weight, but values range from 16 to 28%. The aleurone layer varies from one to five cell layers; it is thicker at the dorsal than at the ventral side and thicker in short-grain than in long-grain rice [ 23 ]. The aleurone and embryo cells are rich in protein and lipid bodies [ 24 ].

The different layers of rice contain different quantities of nutrients. The bran layer is rich in dietary fibre, minerals and vitamin B complex while the aleurone layer contains the least. The endosperm of rice is rich in carbohydrate and also contains a reasonable amount of digestible protein, with favourable amino acid profile than other grains [ 25 ].

Rice processing

Processing of rice mainly involves milling of rice which converts paddy into rice by removing the hull and all or part of the bran layer. Milling of rice is a crucial stage and the objective of milling is to remove the husk and bran so as to produce an edible white rice kernel that is free from impurities.

Rabbani and Ali [ 26 ] report that as a result of processing, some essential nutrients like thiamine and vitamin B are lost. The milling process followed by polishing destroys 67% of the vitamin B 3 , 80% of vitamin B 1 , 90% of vitamin B 6 , 50% of manganese and phosphorus, 60% of the iron, and all of the dietary fibre, as well as the essential fatty acids present in the raw unmilled variety.

The rough rice (also, paddy) on milling produces brown rice, milled rice, germ, bran, broken and husk. Each of these has unique properties and can be used in numerous ways. The extent of value addition in rice and rice products depends upon the utilisation pattern of these components directly or as derivatives. For coloured rice varieties, only the first three steps of milling, namely, pre-cleaning, dehusking and separation, are applied and bran and germ are left intact.

Nutritional information

Raw, long-grain white rice is a good source of carbohydrates, calcium, iron, thiamine, pantothenic acid, folate and vitamin E when compared with maize, wheat and potatoes. It does not contain vitamin C, vitamin A, beta-carotene, lutein and zeaxanthin. It is also notably low in dietary fibre.

Coloured rice

Brown rice retains its bran layer (containing vitamins, minerals and fibre), as this has not been polished more to produce white rice. The coloured rice varieties are either semi-polished or unpolished (Fig. 2 ). Red-coloured rice varieties are known to be rich in iron and zinc, while black rice varieties are especially high in protein, fat and crude fibre. Red and black rice get their colour from anthocyanin pigments, which are known to have free radical scavenging and antioxidant capacities, as well as other health benefits.

Some traditional South Indian rice varieties. a Red Kavuni . b Kaivara Samba . c Kuruvi Kar . d Poongar . e Kattu Yanam . f Koliyal . g Maappillai Samba. h Black Kavuni . Kavuni possesses anti-microbial activity. Kaivara Samba lowers blood sugar levels. Kuruvi Kar is resistant to drought and consumed by the locals for its health benefits. Poongar is consumed by women after puberty and is believed to avert ailments associated with the reproductive system. Kattu Yanam lowers glucose level in blood and also imparts strength. Koliyal is widely consumed as puttu , a specialty dish. Maapillai Samba has a hypocholesterolemic effect and anti-cancer activity and also improves fertility in men. Black Kavuni is resistant to drought and is popular among locals for its health benefits

Brown rice is highly nutritious. It has low calorie and has a high amount of fibre. Furthermore, it is a good source of magnesium, phosphorus, selenium, thiamine, niacin, vitamin B 6 and an excellent source of manganese. Brown rice and rough rice are rich in vitamins and minerals; this is due to the fact that the vitamins are confined to the bran and husk of the paddy. Rice bran and husk contain a higher amount of calcium, zinc and iron (Table 3 ).

Rice is rich in glutamic and aspartic acids but has a lower amount of lysine. The antinutritional factors that are concentrated mainly in the bran are phytate, trypsin inhibitors, oryzacystatin and haemagglutinin-lectin [ 25 ].

The moisture content plays a significant role in determining the shelf life of foods [ 29 ]. Xheng and Lan [ 30 ] report that moisture influences the milling characteristics and the taste of cooked rice. The differences in genetic makeup and the climatic conditions in which they are cultivated determine the moisture content in rice varieties. As seen from Table 4 , the moisture content of the red rice varieties is variable from 9.3 to 12.94%, the moisture content of brown rice and milled rice is lower than other rice varieties.

Protein is the second major component next to starch; it influences the eating quality and the nutritional quality of rice. In India, the dietary supply of rice per person per day is 207.9 g, this provides about 24.1% of the required dietary protein [ 2 ]. Rice has a well-balanced amino acid profile due to the presence of lysine, in superior content to wheat, corn, millet and sorghum and thus makes the rice protein superior to other cereal grains [ 36 ]. The lysine content of rice protein is between 3.5 and 4.0%, making it the highest among cereal proteins. The endosperm protein comprises of 15% albumin (water soluble), globulin (salt soluble), 5–8% prolamin (alcohol soluble), and the rest glutelin (alkali soluble) [ 27 ].

The coloured rice has high protein content than polished white rice due to the presence of bran. The Srilankan and Chinese varieties have higher protein content than the Indian varieties (Table 4 ). Rice bran proteins are rich in albumin than endosperm proteins. The aleurone protein bodies contain 66% albumin, 7% globulin and 27% prolamin and glutelin [ 37 ].

The fat present in rice is a good source of linoleic acid and other essential fatty acids. The rice does not contain cholesterol [ 36 ]. The lipids or fats in rice are mainly confined to the rice bran (20%, dry basis). It is present as lipid bodies in the aleurone layer and bran. The core of the lipid bodies is rich in lipids and the major fatty acids are linoleic, oleic and palmitic acids [ 38 , 39 ]. Starch lipids present in rice is composed of monoacyl lipids (fatty acids and lysophosphatides) complexed with amylose [ 40 ]. The amount of fat present in various fractions of rice and red rice indicate that red rice varieties from Sri Lanka and India have about 1% fat, while the China red rice has almost doubled this value (Table 4 ).

The presence of fibre in the diet increases the bulk of faeces, which has a laxative effect in the gut. The fibre content is 0.5–1.0% for well-milled rice [ 41 ]. Arabinoxylans, along with β-d-glucan, are the major component of soluble dietary fibre in rice. In addition, rhamnose, xylose, mannose, galactose and glucose are also present in soluble dietary fibre. Insoluble dietary fibre is made up of cellulose, hemicellulose, insoluble β-glucan and arabinoxylans. However, the quantity and amount of non-starch polysaccharide depend upon the rice cultivar, the degree of milling and water solubility [ 42 ]. Among the red rice varieties, Chak-hao amubi (Manipur black rice) has a significantly lower content of crude fibre (Table 4 ).

The variation in ash content of different cultivars of rice may be due to genetic factors or the mineral content of the soil [ 43 ]. The zinc and iron content of red rice is two to three times higher than that of white rice [ 44 ]. The most common minerals found in rice include calcium, magnesium, iron and zinc (Table 3 ).

The proximate composition of rice and its fractions are influenced by the kind of rice and degree of milling, as milling completely or partially removes the bran layer, aleurone layer and embryo. Thus, variation occurs in the nutrition content between the rice fractions of the same rice variety. The variations can be found in the amount of fats, fibre and minerals present in the grain.

Phytochemical composition

The non-nutritive plant chemicals that have a protective or disease-preventing property are known as phytochemicals. The phytochemical compounds are mainly accumulated in the pericarp and bran of the rice kernel. They prevent oxidative damage in foods and also have a wide spectrum of beneficial biological activities.

Phytochemicals present in rice can be divided into the following sub-groups namely carotenoids, phenolics, alkaloids, nitrogen and organo-sulphur containing compounds. Phenolic compounds are further sub-grouped as phenolic acids, flavonoids, coumarins and tannins. Anthocyanins, the major pigment responsible for the colour of red and black rice, are a kind of flavonoids. Maapillai Samba , a kind of red rice from Tamil Nadu, has the highest amount of total polyphenolic compounds and anthocyanin content than the varieties from Sri Lanka, China red rice and Manipur black rice (Table 5 ).

The pigmented cereal grains, such as red and purple/black rice, have phytochemical compounds in higher amounts than non-pigmented varieties. The phytochemicals such as cell wall-bound phenolics and flavonoids are gaining more interest as these compounds can be broken down by digestive enzymes and gut microflora, and as a result, they can be easily absorbed into the body [ 45 ].

The coloured rice bran contains anthocyanins that possess inhibition of reductase enzyme and anti-diabetic activities [ 46 ]. The reductase inhibitors possess anti-androgen effects and are used in the treatment of benign prostatic hyperplasia and to lower urinary tract symptoms. β-sitosterol present in Maappillai Samba (Fig. 2 g) has a hypocholesterolemic effect, improves fertility and also heals colon cancer. Furthermore, stigmasterol found in this variety is a precursor in the production of semi-synthetic progesterone [ 11 ].

Garudan Samba contains 9,12-octadecadienoic acid ( Z , Z ) which has the potential to act as hypocholesterolemic, anti-arthritic, hepatoprotective, 5-alpha-reductase inhibitor, anti-histaminic, anti-coronary and anti-androgenic effects. In addition to these compounds, it also contains several other bioactive compounds [ 47 ].

3-Cyclohexene-1-methanol and α, α,4-trimethyl- present in red Kavuni (Fig. 2 a) possess the anti-microbial activity, and also, 3-hydroxy-4 methoxy benzoic acid is used as a precursor for the synthesis of morphine. In addition to these compounds, fatty acid esters and fatty acids such as dodecanoic acid, ethyl ester (lauric acid ester) and octadecanoic acid are present. Among these bioactive compounds, octadecanoic acid and ethyl esters increase low-density lipoprotein (LDL) cholesterol in the human body [ 48 ].

Health benefits

Depending upon the flavours, culinary needs, availability and its potential health benefits, people choose different varieties of rice. Rice has the ability to provide fast and instant energy. Brown rice and red rice are great sources of fibre, B vitamins, calcium , zinc and iron, manganese, selenium, magnesium and other nutrients. The red and black rice variety gets its rich colour from a group of phytochemicals called anthocyanins, which are also found in deep purple or reddish fruits and vegetables.

Diabetes mellitus

Unlike white polished rice, brown rice releases sugars slowly thus helping to stabilise blood sugar in a sustained manner. This trait makes it a better option for people who are suffering from diabetes mellitus. Further, studies in Asia have shown a relationship between the consumption of white rice and risk of type 2 diabetes. Dietary fibres reduce the absorption of carbohydrates by providing an enclosure to the food, hindering the action of hydrolytic enzymes in the small intestine on food, and increasing the viscosity of food in the intestine [ 49 ]. This plays a vital role in reducing the GI of food thereby preventing the risk of diabetes type 2 [ 50 ]. Proanthocyanidins present in red rice provide protection against type 2 diabetes [ 51 ]. Similarly, anthocyanins present in black rice is said to have a hypoglycemic effect [ 52 ].

Brown rice is rich in manganese and selenium, which play a vital role against free radicals, which acts as a major cancer-causing agent. Due to the presence of these elements and high dietary fibre, brown rice is associated with a lowered risk of cancer. Studies have also correlated the use of whole grains like brown rice with lowered levels of colon cancer. This may be related to its high fibre content, as fibre gets attached to carcinogenic substances and toxins helps to eliminate them from the body, and also keep them away from attaching to the cells in the colon. Proanthocyanins, present in red rice, modulate the inflammatory response and protect against some cancers [ 51 ]. Similarly, anthocyanins which are found abundantly in black rice have anti-carcinogenic properties based on epidemiological and in vivo animal and human-based studies [ 53 ].

Cardiovascular disease

Brown rice may help in lowering the risk of metabolic syndrome, while metabolic syndrome itself is a strong predictor of cardiovascular disease. Red rice contains magnesium that prevents the risk of heart attacks [ 54 ]. Various high-fat diet-induced risk factors for cardiovascular disease were ameliorated by anthocyanin-rich extracts from black rice in rat models [ 55 ].

Cholesterol

Brown rice contains naturally occurring bran oil, which helps in reducing LDL forms of cholesterol. Intake of black rice has found to eliminate reactive oxygen species (ROS) such as lipid peroxide and superoxide anion radicals and lower cholesterol levels due to the presence of compounds such as anthocyanins, polyphenolic compounds, flavonoids, phytic acid, vitamin E and γ-oryzanol [ 56 , 57 ]. Modulation of inflammatory responses by proanthocyanidins in red rice provided protection from cardiovascular disease [ 51 ]. Based on these studies, it is evident that whole grains can lower the chances of arterial plaque buildup, thus reducing the chances of developing heart disease.

Hypertension

Both brown and red rice have high magnesium content than white rice. Magnesium is an important mineral that plays a vital role in the regulation of blood pressure and sodium balance in the body [ 54 ].

Rice varieties such as brown, red and black rice are rich in fibre and have the ability to keep healthy bowel function and metabolic function. Anthocyanins present in red rice have properties that can help in weight management [ 54 ].

Rice protein is hypoallergenic; products from other plant sources such as soy and peanut and animal sources like eggs and milk are a good source of proteins, yet they may cause allergy when consumed. Rice protein provides a solution to this problem because it is hypoallergenic. Furthermore, the anthocyanins present in red rice also have the property to reduce allergy [ 54 ].

Medicinal uses of coloured rice

Among several types of rice, few varieties are used to treat ailments. Every variety of rice is unique in its properties, so the treatment of diseases using rice is not limited to a single variety alone. Many different varieties of rice are employed in treating ailments because of their different properties and characteristics. According to practitioners of Ayurveda, rice creates balance to the humours of the body. Rice enriches elements of the body; strengthens, revitalises and energises the body by removing toxic metabolites; regulates blood pressure; and prevents skin diseases and premature ageing. Rakthasali (a kind of red rice) is efficient in subduing disturbed humours of the body and good for fevers and ulcers; improves eyesight, health, voice and skin health; and increases fertility [ 58 , 59 , 60 , 61 ]. In Ayurveda, Sali , Sashtika and Nivara rice are used to treat bleeding from haemorrhoids (piles); Sali rice is used to treat burns and fractures; Nivara rice is used to treat cervical spondylitis, paralysis, rheumatoid arthritis, neuromuscular disorders, psoriasis, skin lesions, reduce backache, stomach ulcers and snakebite; and Nivara rice is also used in the preparation of weaning food for underweight babies [ 58 , 62 ].

Rice water prepared by soaking rice in water or boiling rice in excess water is used to control diseases. In Ayurvedic preparations, rice varieties such as Mahagandhak ras , Kamdudha ras , Sutsekhar ras , Amritanav ras , Swarnmalti ras , Pradraripu ras , Laghumai ras , Dughdavati , Pradaknasak churna , Pushpnag churna , Sangrahat bhasm and Mukta sukti are used to control ailments such as vaginal and seminal discharges, diarrhoea, constipation and dysentery [ 58 ]. Red rice varieties are known to be used in the treatment of ailments such as diarrhoea, vomiting, fever, haemorrhage, chest pain, wounds and burns [ 63 ]. Matali and Lal Dhan are used for curing blood pressure and fever in Himachal Pradesh. Another red rice variety called Kafalya from the hills of Himachal Pradesh and Uttar Pradesh is used in treating leucorrhoea and complications from abortion [ 64 ]. Kari Kagga and Atikaya from Karnataka are used for coolness and also as a tonic, whereas Neelam Samba of Tamil Nadu is used for lactating mothers [ 65 ]. Kuruvi Kar is resistant to drought and consumed by the locals for its health benefits [ 66 ]. Raktasali is efficient in subduing deranged humours [ 60 , 61 ]. It was also regarded as a good treatment for ailments such as fevers and ulcers. It is also believed that it improves eyesight and voice; acts as diuretic, spermatophytic, cosmetic and tonic; and was also antitoxic [ 59 ].

Traditional food and its importance

Ayurvedic treatises mention red rice as a nutritive food and medicine, so the red rice is eaten as a whole grain. Red rice varieties such as Bhama , Danigora , Karhani , Kalmdani , Ramdi , Muru , Hindmauri and Punaigora of Jharkhand and Chattisgarh are rich in nutrition and provide energy and satiety for a whole day [ 67 , 68 ]. Traditionally, various foods such as pongal , puttu , adai , appam , idli , dosai , idiyappam , adirasam , kozhukattai , modakam , payasam , semiya , uppuma , flaked rice, puffed rice, etc. are prepared and consumed. In Tamil Nadu and Kerala, paddy is parboiled prior to milling. This hydrothermal process facilitates the migration of nutrients such as vitamins and minerals from the bran and the aleurone layer to the endosperm [ 69 ]. Rice takes the place of major cereal consumed in the South Indian diet while it is wheat that holds the position in North Indian diet. Dosai , idli , pongal , appam , semiya , uppuma , kichadi and idiyappam are prepared and consumed for breakfast along with wide varieties of chutney. The specialty dish called puttu made from rice is also prepared and consumed for breakfast. The lunch of South India is a combination of cooked parboiled rice, poriyal , eggs, meat, sambar , dal curry, rasam , pappad , moore (buttermilk) or curd and/or dessert, payasam . The dinner usually consists of idli , dosai , idiappam , cooked rice and curries. Various other dishes are also prepared from rice and include biryani, pulao, fried rice, curd rice, tamarind rice, sambar rice, jeera rice, lemon rice, coconut rice, etc. In Tamil Nadu, appams and idlis are also made using the red rice. Koliyal and Garudan Samba ( Kaadai Kazhuththaan ) of Tamil Nadu are used in the preparation of a specialty dish called puttu [ 47 ]. Flatbread and chapatti are made from red Gunja and glutinous rice is used in making puttu , a South Indian meal [ 70 ]. Several products such as cookies, murruku (a type of South Indian snack), are also made using the various coloured rice varieties.

Rice also plays a major role in festivals celebrated in India. The harvest festivals are celebrated with several delicacies made from freshly harvested paddy. In Tamil Nadu, sarkarai pongal is made from raw rice, green gram, milk and jaggery; in Assam, fried rice balls named ghila pitha are prepared and consumed; in West Bengal, traditional Bengali delicacies are made from freshly harvested rice and jaggery, the most famous one is home-made sweets from rice pitha and karpursal or banapuli , and Basmati rice is also used to make Bengali paish .

Parboiled red rice widely consumed in Kerala includes Thondi , Matta , Paal Thondi , Kuruva , Chitteni and Chettadi . Seeraga Samba is an aromatic rice variety consumed widely in Tamil Nadu and Kerala; it is known as ‘Basmati of South India’ and used in the preparation of biryani. Similarly, Jatu of Kulu valley, Ambemohar of Maharastra, Dubraj of Madhya Pradesh, Joha of Assam, Kamod of Gujarat, Badshah bhog of West Bengal and Odisha, Radhunipagla of West Bengal, Katrini and Kalanamak of Uttar Pradesh and Bihar, Gandha samba of Kerala, Kalajira of Odisha and Chakhao varieties of Manipur are prized for its aroma [ 64 , 67 ].

Today, the spotlight is on the increased production of these traditional varieties, promoting the consumption among the younger generation and production of nutritious and novel value-added products from coloured rice.

Although India is home to traditional red rice varieties and their use has been common among the practitioners of traditional medicine and communities as part of their cultural heritage, their functional effects and health benefits in terms of modern scientific methodology are far and few. Due to the insufficient availability of data, the beneficial properties of these varieties still remain unknown to a majority of the population. So, to leverage their health benefits, extensive research on these native coloured varieties by the stakeholders needs to be promoted so that they are available to consumers as a part of the daily diet or specialty functional foods.

Availability of data and materials

Not applicable

Agricultural Statistics Division, Third advance estimates of production of food grains for 2016-17, Department of Agriculture, Cooperation and Farmers Welfare, India. https://eands.dacnet.nic.in/Advance_Estimate/3rd_Adv_Estimates2016-17_Eng.pdf . Accessed 20 Nov 2018.

Kennedy G, Burlingame B, Nguyen VN. Nutritional contribution of rice and impact of biotechnology and biodiversity in rice-consuming countries, Food and Agriculture Organization of the United Nations. http://www.fao.org/3/Y4751E/y4751e05.htm . Accessed 26 June 2019.

The Hindu, The Hindu Group (2012), ‘From 1,10,000 varieties of rice to only 6,000 now.’ http://www.thehindu.com/news/national/karnataka/from-110000-varities-of-rice-to-only-6000-now/article3284453.ece . Accessed 5 Jan 2019.

Devi GN, Padmavathi G, Babu VR, Waghray K. Proximate nutritional evaluation of rice ( Oryza sativa L.). J Rice Res. 2015;8(1):23–32.

Google Scholar

Gnanamanickam SS. Rice and its importance to human life. In: Biological Control of Rice Diseases. Progress in Biological Control 2009;(8):1-11.

Possehl GL. The Indus Civilization: a contemporary perspective. AltaMira Press. CA; Oxford: Walnut Creek; 2002.

Fuller DQ, Qin L, Harvey E. Evidence for a late onset of agriculture in the lower Yangtze region and challenges for an archaeobotany rice. In: Sanchez-Mazas A, Blench R, Ross MD, Peiros I, Lin M, editors. Past Human Migrations in East Asia, Matching Archaeology, Linguistics and Genetics. London: Routledge; 2007. p. 40–83.

Tewari R, Srivastava RK, Saraswat KS, Singh IB, Singh KK. Early farming at Lahuradewa. Pragdhara. 2008;18:347–73.

Yosida S. Climatic environment and its influence. In: Fundamentals of rice crop science. Manila: International Rice Research Institute; 1981. p. 65.

Ahuja SC, Ahuja U. Rice in religion and tradition. 2 nd International Rice Congress. 2006. https://www.researchgate.net/publication/321334487 . Accessed 23 May 2019.

Sulochana S, Singaravadivel K. A study on phytochemical evaluation of traditional rice variety of Tamil Nadu -'Maappillai Samba' by GC-MS. International Journal of Pharma and Biosciences. 2015;6(3):606–11.

Gomez KA. Rice, the Grain of culture. Siam Society Lecture Series, The Siam Society, Thailand. 2001. https://www.thairice.org/html/article/pdf_files/Rice_thegrain_of_Culture.pdf . Accessed 10 June 2018.

Ricepedia, CGIAR, IRRI, Philippines. Rice as a Crop. www.ricepedia.org/rice-as-a-crop . Accessed 10 Jan 2018.

Food and Agricultural Organisation of the United Nations. Rice Market Monitor FAO. 2017. http://www.fao.org/3/I8317EN/I8317EN.pdf . Accessed 20 Oct 2018.

Department of Agriculture, Cooperation and Farmers Welfare. Ministry of Agriculture, India. 2017. http://agricoop.nic.in/sites/default/files/pocketbook_0.pdf . Accessed 2 Mar 2019.

Directorate of Economics and Statistics (DES), Ministry of Agriculture, India. 2014. https://eands.dacnet.nic.in/PDF/Glance-2016.pdf . Accessed 20 Nov 2018.

Ricepedia, CGIAR, IRRI, Philippines. Cultivated rice species. http://ricepedia.org/rice-as-a-plant/rice-species/cultivated-rice-species . Accessed 10 Jan 2018.

Calpe C. Rice International Commodity Profile. Food and Agricultural Organisation of the United States. 2006. http://www.fao.org/fileadmin/templates/est/COMM_MARKETS_MONITORING/Rice/Documents/Rice_Profile_Dec-06.pdf . Accessed 25 Sept 2018.

Kitano H, Tamura Y, Satoh H, Nagato Y. Hierarchial regulation of organ differentiation during embryogenesis in rice. Plant J. 1993;3:607–10.

Juliano BO, Bechtel DB 1985. The rice grain and its gross composition. In: Juliano BO, editor. Rice Chemistry and Technology, American Association of Cereal Chemists: Eagan, MN, USA. 1985. p. 17-57.

Tangpinijkul N. Rice Milling System: paper prepared for a training course on Grain Post-harvest Technology Manhattan Klongluang Hotel, Pathumthani, Thailand. 2010. https://pdfs.semanticscholar.org/ce4e/874284982e5b7603b0373a554c786c763c8e.pdf . Accessed 25 June 2019.

Kennedy G, Burlingame B, Nguyen N. Nutrient impact assessment of rice in major rice-consuming countries. Food and Agriculture Organisation of the United Nations. http://www.fao.org/3/Y6159T/y6159t04.htm#Note1 . Accessed on 17 July 2019.

Del Rosario AR, Briones VP, Vidal AJ, Juliano BO. Composition and endosperm structure of developing and mature rice kernel. Cereal Chem. 1968;45:225–35.

Tanaka K, Ogawa M, Kasai Z. The Rice Scutellum. II. A comparison of scutellar and aleurone electrodense particles by transmission electron microscopy including energy-dispersive X-ray analysis. Cereal Chem. 1977;54:684–9.

Juliano BO. Rice in human nutrition. FAO Food and Nutrition Series No. 21, Rome, Italy. 1993. 162.

Rabbani GH, Ali M. New ideas and concepts, rice bran: a nutrient dense mill-waste for human nutrition. The ORION Med. J. 2009;32(3):458–62.

Juliano BO. Rice: Chemistry and Technology. 2nd ed. St. Paul, MN: Am. Assoc. Cereal Chem; 1985b. p. 774.

Pedersen B, Eggum BO. The influence of milling on the nutritive value of flour from cereal grains. Plant foods Human Nutrition. 1983;33:267–78.

Ebuehi OAT, Oyewole AC. Effect of cooking and soaking on physical characteristics, nutrient composition and sensory evaluation of indigenous and foreign rice varieties in Nigeria. African Journal of Biotechnology. 2007;6(8):1016–20.

Xheng X, Lan Y. Effects of drying temperature and moisture content on rice taste quality. Agricultural Engineering International: The CIGRE Journal 2007:9. Manuscript FP07 023.

Eggum BO, Juliano BO, Maniñgat CC. Protein and energy utilization of rice milling fractions by rats. Qual. Plant. Plant Foods Hum. Nutr. 1982;31:371–6.

Umadevi M, Pushpa R, Sampathkumar KP, Bhowmik D. Rice- Traditional medicinal plant in India. Journal of Pharmacognosy and Phytochemistry. 2012;1(1):6–12.

Longvah T, Ananthan R, Bhaskarachary K, Venkaiah K. Proximate principles and dietary fibre. Hyderabad, India: Indian Food Composition Tables, National Institute of Nutrition, Department of Health Research, Ministry of Health and Family Welfare, Government of India; 2017. p. 3.

Sompong R, Siebenhandl-Ehn S, Linsberger-Martin G, Berghofer E. Physicochemical and antioxidative properties of red and black rice varieties from Thailand, China and Sri Lanka. Food Chemistry. 2011;124:132–40.

Saikia S, Dutta H, Saikia D, Mahanta CL. Quality Characterisation and estimation of phytochemicals content and antioxidant capacity of aromatic pigmented and non-pigmented rice varieties. Food Research International. 2012;46(1):334–40.

Eggum BO. The nutritional value of rice in comparison with other cereals. In: Proceedings, Workshop on Chemical Aspects of Rice Grain Quality, IRRI. Los Banos, Laguna, The Philippines; 1979. p. 91–111.

Tanaka N, Fujita N, Nishi A, Satoh H, Hosaka Y, Ugaki M. The structure of starch can be manipulated by changing the expression levels of starch branching enzyme IIb in rice endosperm. Plant Biotechnol. J. 2004;2:207–516.

Juliano BO, Goddard MS. Cause of varietal difference in insulin and glucose responses to ingested rice. Qual. Plant. Plant Foods Hum. Nutr. 1986;36:35–41.

Tanaka Y, Resurreccion AP, Juliano BO, Bechtel DB. Properties of whole and undigested fraction of protein bodies of milled rice. Agric. Biol. Chem. 1978;42:2015–23.

Choudhury NH, Juliano BO. Effect of amylose content on the lipids of mature rice grain. Phytochemistry. 1980;19:1385–9.

Oko AO, Onyekwere SC. Studies on the proximate chemical composition and mineral element contents of five new lowland rice varieties in Ebonyi State. Int J Biotechnology Biochemistry. 2010;6(6):949–55.

Lai VMF, Lu S, He WH, Chen HH. Non-starch polysaccharide compositions of rice grains with respect to rice variety and degree of milling. Food Chemistry. 2007;101(3):1205–10.

AO O, BE U, AA E, N D. Comparative analysis of the chemical nutrient composition of selected local and newly introduced rice varieties grown in Ebonyi State of Nigeria. Int J Agriculture Forestry. 2012;2(2):16–23.

Ramaiah K, Rao MVBN. Rice breeding and genetics ICAR science monograph 19. New Delhi, India: Indian Council of Agricultural Research; 1953.

Chen C-H, Yang J-C, Uang Y-S, Lin C-J. Improved dissolution rate and oral bioavailability of lovastatin in red yeast rice products. Int J Pharm. 2013;444(1-2):18–24.

Yawadio R, Tanimori S, Morita N. Identification of phenolic compounds isolated from pigmented rices and their aldose reductase inhibitory activities. Food Chemistry. 2007;101(4):1616–25.

Sulochana S, Meyyappan RM, Singaravadivel K. Phytochemical screening and GC-MS analysis of Garudan Samba traditional rice variety. Int J Environ Agri Res. 2016;2(4):44–7.

Sulochana S, Meyyappan RM, Singaravadivel K. Mass spectrometry analysis of indian traditional variety “Red Kavuni” in comparison with high yielding popular variety of Tamil Nadu ADT 43 under raw and hydrothermally processed condition. Indo Am J Pharm Res. 2016;6(5):5358–63.

Jenkins DJA, Leeds AR, Gassell MA, Cocket B, Alberti KGM. Decrease in post-prandial insulin and glucose concentrations by gaur and pectin. Ann Intern Med. 1977;86:20–3.

Babu DP, Bhakyaraj R, Vildhyalakshmi R. A low cost nutritious food “tempeh”- a review. World J. Dairy Food Sci. 2009;4(1):222–7.

Chen M-H, McClung AM, Bergman CJ. Concentrations of ligomers and polymers of proanthocyanidins in red and purple rice bran and their relationships to total phenolics, flavonoids, antioxidant capacity and whole grain color. Food Chemistry. 2016;208:279–87.

Tsuda T, Horio F, Uchids K, Aoki H, Osawa T. Dietary cyanidin 3-O-beta-D-glucoside-rice purple corn color prevents obesity and ameliorates hyperglycemia in mice. J. Nutr. 2003;133(7):2125–30.

Pojer E, Mattivi F, Johnson D, Stockley CS. The case for anthocyanin consumption to promote human health: a review. Compr. Rev. Food Sci, Food Saf. 2013;12(5):483–508.

Institute of Medicine (US). Standing Committee on the Scientific Evaluation of Dietary References Intakes. Dietary reference intakes for calcium, phosphorous, magnesium, vitamin D, and fluoride. Magnesium. Washington, DC: National Academies Press; 1997.

Shao Y, Xu F, Sun X, Bao J, Beta T. Identification and quantification of phenolic acids and anthocyanins as antioxidants in bran, embryo and endosperm of white, red and black rice kernels ( Oryza sativa L.). J Cereal Sci. 2014;59:211–8.

Ichikawa H, Ichiyanagi T, Xu B, Yoshii Y, Nakajima M, Konishi T. Antioxidant activity of anthocyanin extract from purple black rice. J. Med. Food. 2001;4(4):211–8.

Nam YJ, Nam SH, Kang MY. Cholesterol - lowering efficacy of unrefined bran oil from the pigmented black rice ( Oryza sativa L cv. Suwon 415) in hypercholesterolemic rats. Food Sci. Biotechnol. 2008;17:457–63.

Ahuja U, Ahuja SC, Thakrar R, Singh RK. Rice- a nutraceutical. Asian Agri-History. 2008;12(2):93–108.

Bhat FM, Riar CS. Health benefits of traditional rice varieties of temperate regions. Med. Aromat. Plants. 2015;4:198. https://doi.org/10.4172/2167-0412.1000198 .

Krishnamurthy KS. The Wealth of Susruta. Tamil Nadu, India: International Institute of Ayurveda, Coimbatore; 1991.

Kumar TT. History of rice in India. Delhi, India: Gian Publishers; 1988.

Sharma PV. Classical uses of medicinal plants. Chaukhamba Vishwabharati, Varanasi. Uttar Pradesh, India. 1996:848.

Hedge S, Yenagi NB, Kasturiba B. Indigenous knowledge of the traditional and qualified Ayurveda practitioners on the nutritional significance and use of red rice in medications. Indian journal of traditional knowledge. 2013;12:506–11.

Ahuja U, Ahuja SC, Chaudhary N, Thakrar R. Red rices-past, present, and future. Asian Agri-History. 2007;11(4):291–304.

Arumugasamy S, Jayashankar N, Subramanian K, Sridhar S, Vijayalakshmi K. Indigenous rice varieties. Centre for Indian Knowledge System (CIKS), Chennai: Tamil Nadu India; 2001.

The Hindu. The Hindu Group. India: India. Indigenous rice varieties make a comeback The Hindu Group; 2018. http://www.thehindu.com/life-and-style/food/thanals-save-our-rice-is-reviving-indigenous-rice-varieties/article22420554.ece .

Ahuja U, Ahuja SC, Thakrar R, Shobha Rani N. Scented rices of India. Asian Agri-History. 2008;12(4):267–83.

Rahman S, Sharma MP, Sahai S. Nutritional and medicinal value of some indigenous rice varieties. Indian J Traditional Knowledge. 2006;5(4):454–8.

Bhattacharya KR. Parboiling of rice. In: Champagne NET, editor. Rice chemistry and technology. American Association of Cereal Chemists Inc. St. Paul, Minnesota; 2004. p. 329–404.

Rani S, Krishnaiah K. Current status and future prospects of improving traditional aromatic rice. In: Chaudhary RC and Tran DV, editors, Specialty Rices of the World: Breeding, Production, and Marketing, FAO, Rome, Italy and Oxford IBH Publishers, India. 2001. p. 49-79.

Download references

Acknowledgements

The authors wish to thank the anonymous reviewer(s) for their suggestions.

Author information

Authors and affiliations.

Centre for Food Technology, Department of Biotechnology, Alagappa College of Technology, Anna University, Guindy, Chennai-25, India

Rathna Priya T. S., Ann Raeboline Lincy Eliazer Nelson, Kavitha Ravichandran & Usha Antony

You can also search for this author in PubMed Google Scholar

Contributions

RP initiated the idea of the article and authored all sections of the article except sections on medicinal uses of coloured rice, traditional food products and value-added products and new products. ARLEN authored sections on medicinal uses of coloured rice, traditional food products and value-added products and new products; co-authored other sections of the article KR co-authored the sections on the importance of rice in India, rice processing, production and demand of rice varieties, origin and spread of rice and value-added products and new products; and provided critical inputs to revise the manuscript. UA co-authored the sections on structure of grain, nutrition, health benefits and traditional food products; and provided critical inputs to revise the manuscript. All the authors read and approved the final manuscript.

Corresponding author

Correspondence to Kavitha Ravichandran .

Ethics declarations

Competing interests.

The authors declare that they have no competing interests.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License ( http://creativecommons.org/licenses/by/4.0/ ), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated.

Reprints and permissions

About this article

Cite this article.

Rathna Priya, T., Eliazer Nelson, A.R.L., Ravichandran, K. et al. Nutritional and functional properties of coloured rice varieties of South India: a review. J. Ethn. Food 6 , 11 (2019). https://doi.org/10.1186/s42779-019-0017-3

Download citation

Received : 21 January 2019

Accepted : 12 September 2019

Published : 21 October 2019

DOI : https://doi.org/10.1186/s42779-019-0017-3

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

Polyphenols
Phytochemicals

Journal of Ethnic Foods

ISSN: 2352-619X

Submission enquiries: Access here and click Contact Us
General enquiries: [email protected]

Crop Science
Agriculture
Cereal Crops
Agricultural Crops

Rice in health and nutrition

January 2014
International Food Research Journal 21(1):13-24

Universitas Gadjah Mada
This person is not on ResearchGate, or hasn't claimed this research yet.

The University of Tokyo

Abstract and Figures

Discover the world's research

25+ million members
160+ million publication pages
2.3+ billion citations

Abubakar Haruna

Ruth Linus Edem

Blessing Chidi Obasi

PRADEEP KUMAR DAS MOHAPATRA
Rosina Baadu

Jualang Azlan Gansau

Ayodele Martins Ajayi
J FOOD COMPOS ANAL

Mokshil Tandel
ECOTOX ENVIRON SAFE

Paul N. Williams

Andrew A. Meharg
P.N. Williams

Akiko Nanri

Daniel G Garry

NEW ENGL J MED

Eva Obarzanek
R.G. Krishnamurthy
N.O.V. Sonntag

K. Trongvanichnam
Recruit researchers
Join for free
Login Email Tip: Most researchers use their institutional email address as their ResearchGate login Password Forgot password? Keep me logged in Log in or Continue with Google Welcome back! Please log in. Email · Hint Tip: Most researchers use their institutional email address as their ResearchGate login Password Forgot password? Keep me logged in Log in or Continue with Google No account? Sign up

Academia.edu no longer supports Internet Explorer.

To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser .

We're Hiring!
Help Center
Most Cited Papers
Most Downloaded Papers
Newest Papers

Enter the email address you signed up with and we'll email you a reset link.

Academia.edu Journals
We're Hiring!
Help Center
Find new research papers in:
Health Sciences
Earth Sciences
Cognitive Science
Mathematics
Computer Science
Academia ©2024

Access through your organization

Article preview

Introduction, section snippets, references (24), cited by (10).

Engineering in Agriculture, Environment and Food

Research paper long-term storability of rough rice and brown rice under different storage conditions ☆, design of storage tests, variations in rice temperature and relative humidity during storage under different storage conditions, summary and conclusions, development of a low-moisture-content storage system for brown rice storability at decreased moisture content, biosystems engineering, changes in physicochemical characteristics of rice during storage at different temperatures, j stored prod res, monitoring milling quality of rice by image analysis, computers and electronics in agriculture, effects of freezing rates on starch retrogradation and textural properties of cooked rice during storage, lwt – food sci technol, ageing of stored rice: changes in chemical and physical attributes, j cereal sci, effect of storage temperature on rice thermal properties, food res int, low moisture content limit to the negative logarithmic relation between seed longevity and moisture content in three sub species of rice, effects of moisture content and storage temperature of husked rice on taste and changes in physicochemical properties (in japanese with english abstract), nippon shokuhin kagaku kogaku kaishi, changes in the physicochemical properties of rice with ageing, j sci food agric, rice quality preservation during on-farm storage using fresh chilly air, freezing temperature and freezing injury of rough rice, and quality of rough rice stored at temperatures between −50°c and 25°c for four years, a study on the effect of storage conditions upon rice quality. i. change in quality of milled rice during storage (in japanese with english abstract), journal of the japanese society of agricultural machinery, an adaptive grain-bulk aeration system for squat silos in winter: effects on intergranular air properties and grain quality.

The coma temperature of most stored-grain pests is generally about 5 °C. The supercold point of stored-grain pests ranges from −20 to −10 °C [29], while dry grain does not freeze at −80 °C [30,31]. When the grain bulk temperature is reduced to 5 °C, the loss of stored grain can be completely suppressed [32].

Effects of small-scale storage on the cooking property and fatty acid profile of sea rice paddy

Such large-scale rice production will require effective rice storage; however, the storage properties of sea rice paddy have not been studied. Rice storability is the ability of rice to maintain, during storage, the qualities that are valued by consumers (Qiu et al., 2014). In China, paddy rice is frequently stored for up to two years.

Changes in the chemical, physical, and sensory properties of rice according to its germination rate

The main nutrients in rice are starch, protein, and lipid (Peng et al., 2019). However, most of the harvested rice is stored for a certain period before consumption, and during storage, the chemical, physical, and physiological properties of rice are significantly changed, leading to changes in its nutritional and eating qualities (Park, Kim, Park, & Kim, 2012; Qiu, Kawamura, Fujikawa, & Doi, 2014). In particular, the change in rice properties, such as pasting, color, flavor, and composition, during storage is usually termed as rice aging (Jungtheerapanich, Tananuwong, & Anuntagool, 2017; Peng et al., 2019).

Interleaved attention convolutional compression network: An effective data mining method for the fusion system of gas sensor and hyperspectral

Different storage conditions affect the rice quality. Humidity is one of the factors that affect rice quality [9]. Under the condition of room storage temperature, rice stored in a low humidity environment is easy to preserve and its quality changes slowly.

Rice freshness determination during paddy storage based on solvent retention capacity

Kinetic evaluation of oxidative stability and physical degradation of soybean grains stored at different conditions.

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Publications
Account settings

The PMC website is updating on October 15, 2024. Learn More or Try it out now .

Advanced Search
Journal List
Nutr Metab Insights

Biological Functions and Activities of Rice Bran as a Functional Ingredient: A Review

Suwimol sapwarobol.

1 The Medical Food Research Group, Department of Nutrition and Dietetics, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand

Weeraya Saphyakhajorn

2 Graduate Program in Food and Nutrition, Department of Nutrition and Dietetics, Faculty of Allied Health Sciences, Chulalongkorn University, Bangkok, Thailand

Junaida Astina

Rice bran (RB) is a nutrient-rich by-product of the rice milling process. It consists of pericarp, seed coat, nucellus, and aleurone layer. RB is a rich source of a protein, fat, dietary fibers, vitamins, minerals, and phytochemicals (mainly oryzanols and tocopherols), and is currently mostly used as animal feed. Various studies have revealed the beneficial health effects of RB, which result from its functional components including dietary fiber, rice bran protein, and gamma-oryzanol. The health effects of RB including antidiabetic, lipid-lowering, hypotensive, antioxidant, and anti-inflammatory effects, while its consumption also improves bowel function. These health benefits have drawn increasing attention to RB in food applications and as a nutraceutical product to mitigate metabolic risk factors in humans. This review therefore focuses on RB and its health benefits.

Introduction

Rice (Oryza sativa) is one of the staple foods globally, especially in Asia. Global rice consumption was approximately 490.27 million metric tons in 2019. 1 Rice provides up to 50% of the calories consumed by populations in Asia. 2 Previous studies indicated that rice by-products from the milling process still contain a variety of nutrients and bioactive compounds, which exhibit beneficial health effects. 3 , 4 These by-products could be used or added to food products to promote the yield and food sustainability of rice production. 5

Rice kernels are composed of approximately 70% starchy endosperm (total milled rice), 20% rice husk, and 10% rice bran (RB), depending on the extent of milling and the rice variety. 5 , 6 Milled rice is sold as food for humans, while broken rice, rice husk, and RB, considered as by-products, are commonly used for industrial applications and feed for animals. 7 , 8 Owing to its high-fat content and nutritional value, RB oil is also extracted for use in cooking. 9

A substantial number of in vitro and in vivo studies have shown the benefits of RB for certain health parameters, via its antioxidant activity. Moderate consumption of antioxidant-rich foods is important for scavenging the free radicals that cause oxidative stress, premature cell aging, and heart and muscle damage. 10 However, there is a lack of an updated review study on the effects of RB supplementation on metabolic syndrome. Therefore, this article reviews the health benefits of RB on metabolic indicators.

Nutritional Composition of RB

Rice bran is the brown outer layer of the rice kernel, mainly composed of the pericarp, aleuron, seed coat, and germ. It contains 50% carbohydrate (mainly starch), 20% fat, 15% protein, and 15% dietary fiber (DF), mainly insoluble fiber. 11 , 12 Nutritional composition on crude RB per 100 g were shown in Table 1 . However, the nutrient composition of RB depends on the rice variety and the efficiency of the milling system. 7 Because of these nutrients and bioactive compounds, RB has been tested for its beneficial health effects. 3 , 4

Nutritional information on crude RB per 100 g. 13

Nutrient	Amount
Energy (kcal)	316
Protein (g)	13.35
Total fat (g)	20.85
Saturated fatty acids (g)	4.17
Monounsaturated fatty acids (g)	7.55
Polyunsaturated fatty acids (g)	7.46
Carbohydrate (g)	49.69
Fiber, total dietary (g)	21.00
Minerals
Calcium (mg)	57.00
Iron (mg)	18.54
Magnesium (mg)	781.00
Phosphorus (mg)	1677.00
Potassium (mg)	1485.00
Zinc (mg)	6.04
Manganese (mg)	14.21
Selenium (µg)	15.60
Vitamins
Thiamine (mg)	2.75
Riboflavin (mg)	0.28
Niacin (mg)	34.00
Pantothenic acid (mg)	7.39
Vitamin B6 (mg)	4.07
Folate (µg)	63.00
Choline (mg)	32.20
Vitamin E (alpha-tocopherol) (mg)	4.92
Vitamin K (phylloquinone) (µg)	1.90

Structure of Functional Components of RB

Rice bran dietary fiber.

RB contains approximately 12% DF, 90% of which is insoluble DF including cellulose, hemicellulose, and arabinoxylans. 14 , 15 Pectin and β-glucan, soluble DF, are present in RB at trace levels. 16 However, the amount and composition of nutrients in RB vary depending on the rice cultivar, environmental conditions, degree of milling, and analytical method. 17

A previous study by Ghodrat et al 18 revealed that RB contains approximately 34% cellulose. Cellulose is a long-chain homopolymer with a high degree of polymerization, ranged from several 100 to over 10 000 monomers, and a large molecular weight. 19 , 20 The monomer of cellulose is D-glucose linked by a β-(1→4) bond; it is thus a fibrous and highly water-insoluble polysaccharide that cannot be digested by humans. 21

The effects of cellulose on reducing daily energy intake, glycemic control, and lipid metabolism in humans remain poorly understood. Most studies have consistently reported beneficial health effects of modified celluloses, but not natural celluloses such as high-viscosity hydroxypropylmethylcellulose (HV-HPMC). Previous studies indicated that the characteristics of modified celluloses are similar to soluble fiber, in terms of increasing intestinal viscosity, hindering nutrient absorption, and promoting bile acid excretion. 22 - 24

Hemicellulose

RB contains approximately 22% hemicellulose, 18 with arabinoxylans being the most common hemicelluloses. 14 Arabinoxylans also naturally occur in other major cereal grains such as rye, wheat, barley, oats, maize, and millet, which cannot be digested in the human small intestine. 25 Arabinoxylans consist of a β-(1,4)-linked xylose residue backbone, with substitutions of arabinose residues at the second and third carbon positions. 26 Studies have revealed health benefits of arabinoxylans, including immunomodulatory activity and reduction of the glycemic response. 27 - 31 The mechanism underlying the immunomodulatory activity of arabinoxylans is still unclear, but it was hypothesized that it is mediated by competition with lipopolysaccharides (LPS) from Gram-negative bacteria for the TLR4 receptor of macrophages. 32 The immunomodulatory activity of arabinoxylans depends on several factors, such as the degree of branching, molecular weight, and sugar composition. One type of RB arabinoxylan, known as MGN-3, was shown to be more effective at activating macrophages than wheat bran arabinoxylan due to its higher levels of glucose and galactose side chains. 32 , 33

Gamma-oryzanol

Gamma-oryzanol is present in the form of a steryl ferulate, which is a mixture of ferulic acid esters of sterol and triterpene alcohols. 34 , 35 Gamma-oryzanol is present in approximately 20% of the unsaponifiable fraction in RB oil. 36 In addition, the amount and composition of gamma-oryzanol in RB vary depending on the rice cultivar and extraction method. 4 , 37 Gamma-oryzanol is considered as one of the most effective natural antioxidants. 38 Functional activities of gamma-oryzanol that have been reported include antioxidant activity, antidiabetic activity, lipid-lowering effect, and anti-cancer properties. 38 - 42

Rice bran protein

RB is a good source of high-quality plant-based protein with high digestibility and hypoallergenicity. 43 The protein content of RB is about 10% to 15%, which consists of 37% albumin, 36% globulin, 22% glutelin, and 5% prolamin. 44 However, the distribution of protein fractions in defatted rice bran varies among rice varieties. 44 RB protein has been reported to show good digestibility and biological value, with protein energy ratio, true digestibility, and Protein Digestibility Corrected Amino Acid Score of 2.39, 94.8%, and 0.90, respectively. 45 RB protein is rich in essential amino acids. 45 Moreover, RB is abundant in lysine, a limiting amino acid, compared with other cereal grains. 46 Most previous studies reported that the health benefits of RB protein are related to RB protein isolate, peptides, and hydrolysate. Biological and functional activities of RB protein ( Table 2 ) include antioxidant activity, antihypertensive activity, antidiabetic activity, and a lipid-lowering effect. 47 - 57

Summary of functional activities of RB components.

Source	Amount and duration	Bioactivity	Reference
RB enzymatic extract	1% and 5% in obese Zucker rats, 20 weeks	Weight reduction, antidiabetic, hypolipidemic activity, antihypertensive	Justo et al.
RB enzymatic extract	1% and 5% C57BL/6J mice, 16 weeks	Weight control, hypolipidemic activity, antihypertensive, anti-inflammation	Justo et al.
RB polysaccharides	500 mg/kg in ICR mice, 10 weeks	Weight reduction, hypolipidemic activity, antihypertensive	Nie et al.
RB and plant sterols	RB and RB + 2% plant sterols with 25% energy-restricted diet in overweight and obese adults, 8 weeks	Weight reduction, cholesterol-lowering effect	Hongu et al.
RB extract containing acylated steryl glucoside fraction	30-50 mg/day in in obese Japanese men, 12 weeks	Weight reduction, cholesterol-lowering effect	Ito et al.
Brown RB extract containing acylated steryl glucosides	50 mg in post-menopausal Vietnamese women, 6 months	Weight reduction, cholesterol-lowering effect, anti-inflammation	Nhung et al.
RB powder	70 g/day with low-calorie diet in overweight and obese adults, 12 weeks	Anti-inflammation	Edrisi et al.
Black RB ethanol extract	100 mg/kg in diabetic rats, 28 days	Antidiabetic	Wahyuni et al.
Purple and red rice (Oryza sativa L.) bran extracts	In 3T3-L1 adipocytes (in vitro)	Antidiabetic	Boue et al.
Egyptian RB extract containing 2% γ-oryzanol	In INS-1 cells (in vitro)	Antidiabetic	Kaup et al.
Stabilized RB	20 g in type 2 diabetes patients, 12 weeks	Antidiabetic, hypolipidemic activity	Cheng et al.
Blended oil (sesame and RB oil)	40 mL/day in type 2 diabetes patients, 8 weeks	Antidiabetic, hypolipidemic activity	Devarajan et al.
RB oil	250 mL/day RB oil-modified milk (18 g of RB oil) in type 2 diabetes patients, 5 weeks	Antidiabetic, hypolipidemic activity	Lai et al.
RB	Diet with 30% RB in male C57BL/6N mice, 7 weeks	Hypolipidemic, antioxidative activity	Kang et al.
RB driselase and ethanol fractions	60 g/kg in stroke-prone spontaneously hypertensive rats, 8 weeks	Antidiabetic, hypolipidemic activity, antihypertensive	Ardiansyah et al. (2007)
RB protein hydrolysates	250 and 500 mg/kg/day in male Sprague–Dawley rats, 6 weeks	Antidiabetic, hypolipidemic activity, antihypertensive, anti-inflammation, antioxidant, restoration of normal endothelial function	Senaphan et al.
RB protein hydrolysates	50 and 100 mg/kg/day in male Sprague–Dawley rats, 6 weeks	Antihypertensive, anti-inflammation, antioxidant, restoration of normal endothelial function	Boonla et al.
RB-derived tripeptide	0.25 mg/kg of peptide in spontaneously hypertensive rats	Antihypertensive	Shobako et al.
RB-contained novel peptide, Leu-Arg-Ala (LRA)	43 μg LRA/day in individuals with high-Normal blood pressure, 12 weeks	Antihypertensive	Ogawa et al.
Defatted RB protein hydrolysates	In Raw 264.7 macrophages (in vitro)	Antioxidant, anti-inflammation	Saisavoey et al.
RB protein hydrolysates	80 mg/kg in male spontaneously hypertensive rats	Antioxidant, antihypertensive	Piotrowicz et al.
RB protein hydrolysates	In vitro	Antidiabetic, antihypertensive	Uraipong and Zhao
Virgin RB oil	2 mL/kg in hypertensive rats, 3 weeks	Antioxidant, anti-inflammation, antihypertensive	Jan-On et al.

Biological and Functional Activities of RB

Antioxidant activity of rb.

RB possesses high antioxidant activity due to its phytochemical compounds and bioactive peptides. 51 , 58 - 60 Previously, an in vitro study showed that the antioxidant activity of RB was influenced by different treatments, such as hot air and far-infrared radiation (FIR). The inhibition of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging activity was increased (to 92.21%) following FIR treatment, compared with the level for raw RB (87.93%). The FRAP also increased from 28.57 µmol FeSO 4 /g in raw RB to 34.41 µmol FeSO 4 /g in FIR-treated RB. 60 The antioxidant activity of RB might be attributable to the phenolic and flavonoid compounds in RB, such as hydroxybenzoic acids, hydroxycinnamic acids, and kaempferol, with total phenolic content and total flavonoid content of RB being 3.05 to 4.05 mg/gallic acid equivalent and 3.08 to 3.88 mg retinol equivalents/g, respectively. 60 Furthermore, RB is a good source of γ-oryzanol, with it being present at a rate of 5.3 to 5.7 mg/g. Tocopherols (α- and γ-form) have also been detected in RB, at levels of 63.5 to 95.8 µg/g and 5.0 to 5.1 µg/g, respectively. 60

Supplementation of RB also showed favorable effects on serum and liver antioxidant levels in rats. 61 Hypercholesterolemia has been shown to stimulate the production of reactive oxygen species (ROS) and decrease serum antioxidant activity. 62 In addition, supplementation with aqueous enzymatic extract of RB (750 mg/kg BW) for 42 days significantly restored serum total antioxidant capacity and superoxide dismutase (SOD) activity in rats fed a high-fat diet, by 36.6% and 83.98%, respectively, compared with the findings in rats fed a high-fat diet only (without RB). Furthermore, RB supplementation in high-fat diet-fed rats increased liver catalase and decreased protein carbonyl content in the liver compared with the levels in rats fed a high-fat diet only due to the antioxidant activity of RB, attributable to oryzanol, tocopherol, polyphenol, and flavonoid compounds. 61 In a clinical study, daily consumption of 30 ml of RB oil containing >4000 ppm of γ-oryzanol for 4 weeks significantly increased plasma oxygen radical absorbance capacity and fluorescence recovery after photobleaching (FRAP) in hyperlipidemic adults. 63 In addition, the antioxidant activity of RB is contributed to by not only polyphenols, flavonoid, oryzanol, and tocopherol, but also bioactive peptides. 51

Peptide from RB protein hydrolysate (RBP) also showed potential health benefits by exerting antioxidant activity. Boonla et al 51 found that supplementation of RBP (50 or 100 mg/kg) for 6 weeks significantly decreased plasma malondialdehyde (MDA) and protein carbonyl in sham-operated rats.

Several epidemiological studies revealed the association between oxidative stress and NCDs. Moreover, antioxidant-containing foods have also attracted a lot of attention due to their beneficial health effects. 64 - 66 Previous studies indicated that the intake of antioxidants and antioxidant-containing foods is associated with a reduced risk of NCDs. 67 - 69 These previous studies show that RB possesses antioxidant ability, which may be important for alleviating the risk of NCDs associated with oxidative stress. Therefore, further research is needed to investigate the antioxidant activity of RB in order to obtain a better understanding of its mechanism of action and effect in humans.

Effect of RB on weight management

Obesity is one of the risk factors of many diseases, such as cardiovascular diseases, type 2 diabetes, certain types of cancer, and hypertension. 70 It is increasingly prevalent not only in adults, but also in children. Childhood obesity increases the risk of obesity in adulthood, as well as other obesity-related diseases. 71 Shifting dietary patterns, economic growth, and globalization have contributed to the increasing prevalence of obesity globally. Economic transitions have also resulted in the intake of more processed foods, which have been shown to be related to obesity. 70 , 72

Previously, Giacco et al 73 concluded that higher whole-grain intake leads to a lower body weight by lowering the glycemic index, lowering energy density, producing short-chain fatty acids (SCFAs), and modulating gut microbiota. However, recent clinical studies found a lack of evidence to support the beneficial effects of whole grains on weight loss, despite possible mechanisms by which the consumption of whole grains could promote weight loss, such as increasing chewing, reducing energy density and availability, reducing postprandial glycemic response, increasing fermentation, and promoting gut microbiota in the colon. 74

As a component of whole grains, the effect of consuming RB on weight management has been investigated in animal and human studies. 54 , 56 , 75 , 76 Justo et al 77 investigated the effects of RB enzymatic extract (1% and 5% supplemented diet) on metabolic, biochemical, and functional adipose tissue changes related to diet-induced obesity in mice. The results showed that a high-fat diet significantly increased body weight compared with a standard diet. Mice fed a high-fat diet supplemented with 1% and 5% RB extract did not show any differences in body weight compared with mice consuming a high-fat diet. Mice fed a high-fat diet had an adipocyte size distribution (100-400 µm 2 ) larger than that of mice fed a standard diet (<100 µm 2 ). 77 Interestingly, supplementation with 1% RB in the high-fat diet of mice restored the adipocyte size distribution as well as the inflammatory cytokines to normal levels. 77 These effects could have been mediated by oryzanol as the main active component of RB by upregulating Peroxisome Proliferator-Activated Receptor (PPAR)-γ expression in adipocytes. 78 In addition, in a high-fat-diet animal model, mice intragastrically administered 500 mg/kg RB polysaccharide solution for 10 weeks had significantly reduced body weight compared with the control group. 54 It was suggested that RB polysaccharides prevented weight gain by regulating the expression of lipid metabolism-related genes including PPAR-α, PPAR-γ, PPAR-δ, Sterol Regulatory Element-Binding Protein (SREBP)-1C, Fatty Acid Synthase (FASN), Acetyl-CoA Carboxylase Alpha, Sirtuin (SIRT), and CD36. 54 In contrast, RBP (500 mg/kg/day) did not affect body weight in rats fed a high-carbohydrate and high-fat diet. 56

Studies on humans have reported inconsistent effects of RB consumption on weight loss. 75 , 76 , 79 , 80 Rice bran extract reduced abdominal circumference and subcutaneous fat area following the consumption of 30 to 50 mg/day of RB extract for 12 weeks in obese Japanese men with high low-density-lipoprotein (LDL) cholesterol. 76 In addition, supplementation with RB extract (50 mg) for 6 months in post-menopausal Vietnamese women with high LDL cholesterol did not significantly alter body mass index. 80 However, in that study, body fat percentage, hip circumference, and abdominal circumference significantly decreased at month 6 when compared with the levels at baseline, although there were no significant differences when compared to a placebo. 80 Another study investigated the effect of pigmented RB bar consumption with or without plant sterols for 8 weeks in obese adults receiving a 25% calorie-restricted diet. 75 Each participant consumed 3 RB bars, which contained 16.7% RB per serving (30 g), with or without 2% plant sterol daily. The results showed that body weight decreased by 4.7 ± 2.2 kg ( P < .001) and body fat decreased in all participants, but these weight losses were not significantly different between the plant sterol groups. 75 However, it is unclear whether the body weight and body fat reductions were due to the pigmented RB or the calorie deficit. 75 In a randomized controlled trial of 105 overweight and obese adults, the participants received a low-calorie diet with RB (70 g/day), a low-calorie diet with rice husk (25 g/day), or a low-calorie diet alone for 12 weeks. 81 The results demonstrated that body weight, body mass index, and waist circumference were significantly reduced in all groups. The study concluded that the reduction of anthropometric indices of obesity in this study might be explained by the energy-restricted diet combined with RB and rice husk supplementation. 81 More studies are needed to clarify the effect of RB on body weight management.

Effect of RB on glycemic control

RB and its components have demonstrated the ability to alleviate hyperglycemia and its associated complications. 82 , 83 Many in vitro studies have suggested that RB extracts inhibited α-glucosidase and α-amylase activity, and increased glucose uptake in 3T3-L1 adipocytes, so they may lower glucose absorption and postprandial glycemic response. 84 , 85 RB extracts also stimulate glucose uptake into cells by inducing the messenger ribonucleic acid (mRNA) expression of glucose transporters (GLUT1 and GLUT4) and insulin-signaling pathway proteins, such as insulin receptor gene (INSR) and insulin receptor substrate (IRS)1, 84 , 85 as well as inducing the release of insulin in INS-1 cells. 86 In addition, reduction in blood glucose and enhancement of hepatic glucokinase activity by the phenolic acid fraction of RB were reported in C57BL/KsJ db/db mice after 17 days of oral administration. 87 Glucokinase is an important regulator of blood glucose, which promotes glucose utilization in the liver by facilitating the phosphorylation of glucose into glucose-6-phosphate. 87

The effects of RB on blood glucose have also been studied in humans. 88 - 91 A low-fiber diet supplemented with RB fiber (40 g/day) for 7 days showed greater effects in lowering fasting and postprandial serum glucose levels in diabetic patients than a low-fiber diet alone. 92 A 12-week intervention of stabilized RB (20 g/day) in type 2 diabetic patients resulted in significant reductions in fasting blood glucose, postprandial glucose, and glycated hemoglobin (HbA1c) when compared with baseline levels. 88 The results also suggested that stabilized RB may affect insulin secretion as fasting insulin and area under the curve insulin were increased when compared with the levels with a placebo. This suggests that RB supplementation may improve insulin resistance because the levels of adiponectin, which has been linked to whole-body insulin sensitivity, were also increased. However, RB supplementation did not significantly alter Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) and no clear effect of RB on adiponectin was observed in this study. 88 In a similar vein, another study showed significantly reduced fasting and postprandial blood glucose levels among type 2 diabetes mellitus (DM) patients who were on RB supplementation of 20 g/day for 30 days, compared with their baseline levels. 93

RB oil is widely produced in Thailand and India and is utilized as cooking oil. RB oil is rich in gamma-oryzanol, which confers many health benefits. A combination of 80% RB oil and 20% sesame oil as daily cooking oil (consumption less than 35-40 ml per day) for 8 weeks significantly reduced fasting plasma glucose, postprandial plasma glucose, and HbA1C in type 2 DM patients when compared with the baseline. 90 The effect was greater with the administration of glibenclamide; this implies that RB oil blend works synergistically with glibenclamide to lower blood glucose response in type 2 DM patients. 90 It is possible that gamma-oryzanol in RB oil attenuates pancreatic beta-cell dysfunction and promotes glucose-stimulated insulin secretion. 90 In contrast, a study found that fasting and postprandial blood glucose levels were increased following supplementation of 18 g of RB oil in milk consumed daily for 5 weeks, compared with a placebo (18 g of soybean oil in milk). The researchers stated that the higher amount of palmitic acid in RB oil than in soybean oil may have induced insulin resistance in L6 skeletal myotubes. 91

Lipid-lowering effect of RB

Studies on mice fed an RB diet showed that they exhibited significantly lowered total blood cholesterol and liver cholesterol concentrations, mainly via an increase in fecal lipid excretion and the regulation of lipogenic enzyme activities. 94 , 95 Malic enzymes and fatty acid synthase were found to be significantly reduced following RB supplementation (30% of diet) for 7 weeks in mice fed a high-fat diet. 95 Malic enzymes were shown to contribute to cellular nicotinamide adenine dinucleotide phosphate (NADPH) production, which is involved in fatty acid and cholesterol biosynthesis, while fatty acid synthase is a co-factor of NADPH. 95 Furthermore, the supplementation of RB and RB oil in high-fat diet-fed rats also downregulated the expression of β-hydroxy β-methylglutaryl (HMG)-CoA reductase mRNA, a rate-limiting enzyme of cholesterol synthesis, and hepatic malondialdehyde. 96

Several studies on humans have also been conducted to investigate the effect of RB on blood lipids. In a 12-week intervention with stabilized RB (20 g/day), significant reductions in serum levels of total cholesterol, LDL, and LDL to high-density lipoprotein (HDL) ratio were found in type 2 diabetic patients. 88 Gamma-oryzanol supplements with PUFA n-3 and vitamin E significantly restored a normal lipid profile in dyslipidemic patients after 4 months of intervention, compared with the placebo and PUFA n-3 with vitamin E groups. 97 A randomized controlled trial showed that serum triglyceride levels were significantly reduced and HDL levels were significantly increased, with a tendency for (non-significant) decreasing trends in total cholesterol and LDL in type 2 diabetic patients after receiving 20 g/day of soluble RB for 30 days. 93 In obese Japanese men with high LDL cholesterol, the consumption of RB extract at 30 to 50 mg/day for 12 weeks significantly reduced total cholesterol, LDL cholesterol, and non-HDL cholesterol levels. 76 Supplementation with RB extract (50 mg) for 6 months also significantly reduced LDL cholesterol and the risk of atherosclerosis compared with placebo in post-menopausal Vietnamese women with high LDL cholesterol. 80 In another study, the consumption of pigmented RB with or without plant sterols for 8 weeks also reduced total cholesterol in obese adults who consumed a 25% calorie-restricted diet. The effect was greater in subjects who consumed RB with plant sterols. 75

Effect of RB on hypertension

A meta-analysis and systematic review on the association of dietary protein intake and blood pressure indicated that plant protein and animal protein are effective macronutrients for lowering blood pressure. 98 , 99 RB is an inexpensive by-product with an abundance of proteins, DF, and bioactive phytochemicals, which may be a useful nutritional factor for managing hypertension. 100 Several mechanisms by which RB protein may reduce blood pressure have been proposed, including activity to inhibit angiotensin-converting enzyme (ACE), upregulation of endothelial nitric oxide synthase (eNOS) protein, and antioxidant activity, leading to the improvement of endothelial function and blood pressure. 51 , 101 , 102 Boonla et al 51 investigated the antihypertensive effects of peptides derived from RBP in a rat model of 2 kidney–one clip (2K-1C) renovascular hypertension. In that study, rats were intragastrically administered either 50 or 100 mg/kg of RBP or distilled water (control) for 6 weeks. Blood pressure and peripheral vascular resistance were significantly decreased in 2K-1C rats treated with RBP compared with those in control rats ( P < .05). 51 RB protein hydrolysates also significantly reduced plasma ACE, decreased superoxide formation, reduced plasma MDA, increased plasma nitrate/nitrite, and increased eNOS protein expression ( P < .05), which are associated with the restoration of endothelial function. 51 Moreover, supplementation with RB protein hydrolysates alleviated the effects of a high-carbohydrate/high-fat (HCHF) diet, namely, hyperglycemia, insulin resistance, dyslipidemia, hypertension, increased aortic pulse wave velocity, aortic wall hypertrophy, and vascular remodeling, by mitigating these alterations. 56 RBP also significantly reduced ACE, decreased plasma MDA, decreased superoxide production, increased plasma nitrate/nitrite, upregulated eNOS expression, and increased nitric oxide production in blood vessels of HCHF-diet-fed rats. 56 This study suggests that RBP has beneficial effects against vascular alterations and the risk of cardiovascular disease through several mechanisms involving enhanced NO (nitric oxide) bioavailability, and anti-ACE, anti-inflammatory, and antioxidant effects. 56 Another study found novel bioactive peptides derived from RB protein, Leu-Arg-Ala (LRA), to be a vasorelaxant. 103 In that study, LRA significantly relaxed the mesenteric artery of spontaneously hypertensive rats (SHRs) with EC 50 = 0.1 µM, which is claimed to be the most potent vasorelaxant derived from grain peptides. 103 The tripeptides relaxed the endothelial cells via the endothelial NO system by inducing the phosphorylation of eNOS in endothelial cells without altering eNOS expression. LRA also decreased systolic blood pressure 4 hours after oral administration in SHRs. 104

A recent clinical trial of 100 individuals with high-normal blood pressure or grade 1 hypertension investigated the effect of processed RB containing peptide Leu-Arg-Ala (43 µg/day) or placebo for 12 weeks on blood pressure. 103 The results showed that subjects who consumed RB had significantly lower systolic blood pressure than those with placebo at the end of the study ( P = .0497), without any serious adverse effects. 103 Peptides used in the study (Leu-Arg-Ala) promoted vascular smooth muscle relaxation by activating eNOS, which synthesized NO in endothelial cells. 103 Nitric oxide plays an important role in vascular smooth muscle tone. Decreased NO availability leads to endothelial dysfunction and raises blood pressure. 105 These findings reveal that RB protein may be an important component for the preventing and treating hypertension. Therefore, further research is required to investigate the hypotensive effect of RB protein in humans.

Effect of RB on inflammation

The effect of RB on inflammation has been studied in vitro and in vivo. In 2013, Hou et al 106 investigated the effect of anthocyanin-rich black RB extract (200, 400, or 800 mg/kg) for 7 weeks in tetrachloride (CCl 4 )-treated mice. The results showed that anthocyanin-rich RB extract normalized liver enzymes, increased plasma antioxidants (SOD and glutathione peroxidase), as well as reduced thiobarbituric acid reactive substances (TBARS, expressed as MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG) . 8-OHdG is a biomarker of oxidative stress as guanine in DNA is transformed into 8-oxo-Gua by a repair process and removed from the body as 8-OHdG; thus, its levels are increased in certain disease conditions, such as atherosclerosis and DM. 42 Meanwhile, MDA is a secondary product of lipid peroxidation and widely used as a biomarker of oxidative stress. The amount of MDA is increased in various diseases related to inflammation, such as cardiovascular diseases, cancer, DM, Alzheimer’s disease, liver disease, and Parkinson’s disease. 107 Similarly, peptides derived from Thai RB decreased superoxide formation, reduced plasma MDA, and improved endothelial function in 2K-1C hypertensive rats. 51 Moreover, RBP exhibited anti-inflammatory activity as evidenced by reductions of IL-6 and TNF-α (proinflammatory cytokines) and an increase of IL-10 (anti-inflammatory cytokine) in Raw 264.7 macrophage cells. 108 Protein hydrolysate from defatted RB was found to exert antioxidant and ACE inhibitory properties. 51 , 52 , 56 , 109 Rice bran protein was hydrolyzed with alcalase or flavorzyme to obtain RBP. The results showed that RBP fractions lower than 3 kDa possessed the strongest antioxidant activity, and had the highest level of total phenolic compounds and most potent ACE inhibitory properties. 109

Recently, it was found that virgin rice brain oil reduced oxidative stress and inflammation in rats with hypertension induced by N(omega)-nitro-L-arginine methyl ester. 110 Decreased NO bioavailability has been linked to increased production of ROS and leads to endothelial dysfunction and hypertension. 111 Virgin RB oil is rich in oleic acid, linoleic acid, γ-oryzanol, phytosterols, tocopherols, and tocotrienols, which upregulate eNOS and downregulate gp 91phox and P-NF-κB protein expression in aortic tissue. As eNOS protein expression is upregulated by virgin RB oil, it would increase the availability of NO and thus reduce inflammation. 110

In a randomized trial of 105 overweight and obese adults, RB (70 g/day), rice husk (25 g/day), and placebo with an energy-restricted diet were administered. After 12 weeks of intervention, serum levels of high-sensitivity C-reactive protein (hs-CRP) were significantly decreased in the RB and rice husk groups compared with the baseline. The reductions of hs-CRP and IL-6 in the RB group were significantly greater than those in the placebo group, whereas no significant change was found in the placebo group. 81

Effect of RB on gastrointestinal functions

Fiber consumption is known to promote gut health. 112 However, excess amounts of fiber may cause bloating and gastrointestinal disturbance due to the fermentation of fiber in the colon by gut bacteria. 113 Daily supplementation with RB (30/g) in colorectal cancer patients for 4 weeks helped to meet the recommended amount of DF without causing gastrointestinal discomfort and changing the stool consistency. 114 In another study, supplementation of arabinoxylan derived from RB for 4 weeks in inflammatory bowel syndrome (IBS) patients was found to improve reflux, diarrhea, and constipation. 115 The improvement in gastrointestinal functions in IBS patients could be mediated by the immunomodulatory effect as the levels of inflammatory biomarkers were also reduced. Fermentation of RB shifts the gut microbiota and stimulates the mucosal balance in the intestinal tract. 115 Hence, the consumption of RB, as a source of DF, could improve gut health and wellbeing.

Prebiotic properties of RB

RB contains a large amount of DF, which has shown prebiotic properties in some studies. 116 - 119 In 2015, Kurdi and Hansawadi 117 reported that hydrothermal-treated RB (0.22 MPa, 135°C, 0.5-3 hour) produced a mixture of oligosaccharides that stimulated the growth of Bifidobacterium and Lactobacillus . Similarly, oligosaccharides from RB were found to increase the production of SCFAs and change the population of gut microbiota, mainly Bacteroides, Dorea , and Prevotella , following fermentation in fecal samples over 24 hour; the effect was comparable to that of fructo-oligosaccharide. Furthermore, the combination of a polyphenol fraction and oligosaccharides from RB increased the population of F. prausnitzii , without affecting the production of SCFAs. 119 Recently, Zhang et al 116 conducted in vitro gastrointestinal digestion and colonic fermentation of the DF fraction of RB (RBDF) and phenolic-removed RBDF (PR-RBDF). The results showed that RBDF, but not PR-RBDF, increased the population of Lactobacillus spp. after 24 and 48 hour. In addition, the populations of Bifidobacterium spp., A. muciniphila , and F. prausnitzii were higher in RBDF than in PR-RBDF following colonic fermentation. This indicated that not only the fiber fraction of RB, but also phenolic compounds in RBDF, contributed to the prebiotic properties of RB. In an animal study, enzyme-treated RB (4% of diet) for 6 days prevented colitis in a murine model by decreasing Clostridium and Eubacterium and increasing the production of SCFAs, mainly acetate and butyrate, which contributed to reducing inflammation in colitis. 118

RB also showed a prebiotic effect in human studies and improved gut health. 120 , 121 Six months of RB supplementation (1-5 g/day) in weaning Malian and Nicaraguan infants (aged 6-12 months) improved the incidence of diarrheal episodes compared with the level in the control group. This effect was mediated by the changes in the composition of gut microbiota, such as Lachnospiraceae, Bifidobacterium, Veillonella, Bacteroides , and Lactobacillus , in infants receiving RB. In addition, as the incidence of diarrheal episodes was decreased by RB supplementation, the growth of infants was also improved. 121 Previously, 4 weeks of RB supplementation in healthy adults was shown to increase Bifidobacterium and Ruminococcus populations. Furthermore, RB supplementation increased the levels of branched-chain fatty acids and secondary bile aids. 120 It was reported that branched-chain fatty acids could be utilized by gut microbiota, such as Ruminococcus , contributing to intestinal health. 120

Effect of RB on kidney and liver function

Kidney plays an important role in maintaining the water and electrolyte balance. 122 Meanwhile, the progression of various metabolic diseases, such as DM and cardiovascular diseases, was shown to influence the kidney function by generating ROS and inflammatory cytokines. 123 Diabetic nephropathy is one of the most common complications in kidney diseases marked by increased albumin and creatinine levels in urine. Diabetic mice supplemented with RBP (100 or 500 mg/kg/day) for 8 weeks showed significant decreases in urine albumin and creatinine compared with diabetic control mice, which improved the diabetic nephropathy. 55 Similarly, purified γ-oryzanol or the combination of γ-oryzanol and RB oil was reported to improve liver and kidney function in rats treated with cisplatin and a high-fat/sucrose diet. 124 Cisplatin injection was found to induce kidney dysfunction in high-fat/sucrose-fed rats, marked by increases of plasma creatinine and urea, and urine volume, along with decreases of urinary creatinine and creatinine clearance. Supplementation with γ-oryzanol (50 mg/kg) with or without RB oil (300 mg) significantly restored the kidney function. 124 It was suggested that the mechanisms were mediated by γ-oryzanol through its inhibition of inflammatory markers, such as prostaglandin E2 (PGE2), which is involved in the progression of kidney dysfunction. 124 , 125

Furthermore, RB also showed a hepatoprotective effect against a high-fat diet. 124 A high-fat diet causes lipotoxicity, which increases the risk of non-alcoholic fatty liver disease (NAFLD) in combination with a rise of liver enzymes. 126 The pathogenesis of NAFLD begins with the accumulation of free fatty acids and triacylglycerids in the liver, followed by oxidative imbalance, mitochondrial dysfunction, and activation of proinflammatory cytokines. 126 Supplementation of γ-oryzanol (50 mg/kg) with or without RB oil (300 mg) was also reported to improve liver function by decreasing the rises of alanine transaminase and aspartate transaminase levels in rats treated with cisplatin and a high-fat/sucrose diet. 124 Furthermore, supplementation of 0.5% oryzanol for 7 weeks also increased liver glucokinase, while reducing glucose-6-phosphatase (G6pase) and phosphoenolpyruvate carboxy kinase (PEPCK) in mice fed a high-fat diet. 127 Consequently, the use of blood glucose for energy or storage as glycogen was increased, while hepatic glucose production was decreased, thus improving blood glucose homeostasis. 127

Toxicological Effect of RB

Rice bran products, including RB oil and fiber, have been used for human consumption and are safe since no mutagenic and teratogenic effects were observed. 128 Recently, RB extract has been utilized as a food additive and considered to be safe for use given it being assigned Generally Recognized as Safe (GRAS) status by The United States Food and Drug Administration in 2018. 129 Based on GRAS Notification Number 884, the RB extract can be used as a food additive at a maximum level of 1.5% (w/w), which is equivalent to 0.71 and 1.50 g/day for those aged 2 and older, respectively. 129

The toxicity of RB extract has been evaluated in several animal studies. 130 - 132 The injection of RB oil (0.1 ml) into chicken embryo did not significantly affect embryo morphology and no toxicity was observed, so it was considered safe for human consumption. 132 In 2015, El Askary et al. evaluated the acute effects of RB extract and the effects of its repeated administration for 28 days in albino rats. A dose of 2000 mg/kg was administered to evaluate the acute toxicity; meanwhile, repeated oral toxicity was evaluated at concentrations of 100, 500, and 1000 mg/kg. The results showed that there were no significant effects on mortality or pathological abnormalities following the acute administration of 2000 mg/kg. However, the administration of RB extract daily for 28 days at concentrations of 500 and 1000 mg/kg significantly affected the liver and kidneys. The higher maximum dose of RB extract was previously reported by Al-Okbi. 130 Hexane extract of RB was acutely administered orally at increasing doses from 1 to 12 g/kg to mice. The results revealed that doses up to 12 g/kg were safe in mice, which corresponds to 93 g in a human weighing 70 kg. 130

Conclusions

The above review of evidence from both animal and human studies shows that RB exerts glycemic control, hypocholesterolemic, hypotensive, and anti-inflammatory effects, as well as promoting bowel function. As a nutrient-rich by-product from the milling process, RB and its derivatives provide nutrients and bioactive compounds that confer these beneficial health effects. Given that there is evidence pointing to the value of this by-product in attenuating metabolic risk factors, RB and its derivatives can potentially be used as nutritional supplements for the control of metabolic syndrome in humans. RB has potential for improving health outcomes, but studies on the effects of its daily consumption are lacking. Further research is required to investigate the effect of RB and its components on functional food development and health outcomes.

Author Contributions: Suwimol Sapwarobol and Weeraya Saphyakhajorn are responsible for preparation, creation of the initial draft. Suwimol Sapwarobol oversight and responsible for the research activity planning and execution, including mentorship external to the core team. Junaida Astina is responsible for critical review and revise manuscript.

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding: The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: Suwimol Sapwarobol was supported traveling expenses by Chulalongkorn University Office of International Affairs Scholarships for short-term research. This work was also supported by the Medical Food Research Group, Chulalongkorn University.

An external file that holds a picture, illustration, etc.
Object name is 10.1177_11786388211058559-img1.jpg

IMAGES

(PDF) Brown Rice as Useful Nutritional Source
(PDF) Brown spot of rice: an overview
Perceptions about Varieties of Brown Rice: A Qualitative Study from
Identification research location brown rice
21 Rice Infographic ideas
Brown rice and its valuable impacts on human well-being

VIDEO

Spraying of NPK 19:19:19 in rice🌾 #rice #agriculture #research #shorts
Rice research seed sowing 🌾 #rice #phd #gpb #thesis #research #shorts
video 57
Brown Rice is Killing You!
Brown Rice Ghee roast and Soft dosa in same batter #shortsfeed #ytshorts #dosa #brownrice #youtube
Why Brown Rice Should Be Your Go-To Grain! #BrownRiceBenefits #HealthyEating #FiberRichFoods

COMMENTS

Phytochemical Profile of Brown Rice and Its Nutrigenomic Implications
This is because of the presence of various phytochemicals that are mainly located in bran layers of brown rice. Therefore, this paper is a review of publications that focuses on the bioactive compounds and nutrigenomic implications of brown rice.
Brown Rice as Useful Nutritional Source
PDF | On Jul 1, 2020, Naseem Zahra and others published Brown Rice as Useful Nutritional Source | Find, read and cite all the research you need on ResearchGate
Brown rice: a missing nutrient-rich health food
Brown rice (BR) is a traditional health food being rich in various active substances, which have effective preventive and therapeutic effects on many diseases. In this review, we systemically summarized the efficacy of BR on cardiovascular diseases (CVDs), hyperlipidemia, hypertension, diabetes, obesity, osteoporosis, neurodegenerative diseases ...
The effect of a brown-rice diets on glycemic control and metabolic
Brown rice is a whole-grain food that is often assumed to have a lower glycemic index compared to white rice. A few studies have objectively confirmed the effect of a brown-rice diet on glycemic control and metabolic parameters compared to a white-rice diet.
Brown Rice, a Diet Rich in Health Promoting Properties
Brown rice contains relatively higher amounts of dietary fibre, moderate amount of proteins, unsaturated lipids, micronutrients and several bioactive compounds. Some landraces consumed as brown rice have low glycemic index properties; hence they might be helpful to counter the growing type II diabetes. Colored rice varieties with red or purple ...
Brown Rice: Nutritional composition and Health Benefits
Discover the nutritional composition and health benefits of brown rice, a whole grain rice with essential components like pericarp, seed coat, germ, and endosperm.
Comparative study of the nutritional composition of local brown rice
Food Science & Nutrition is an author-friendly journal for the rapid dissemination of fundamental and applied research on all aspects of food science and nutrition.
Arsenic in brown rice: do the benefits outweigh the risks?
Brown rice has been advocated for as a healthier alternative to white rice. However, the concentration of arsenic and other pesticide contaminants is greater in brown rice than in white. The potential health risks and benefits of consuming more brown rice than white rice remain unclear; thus, mainstream nutritional messaging should not advocate for brown rice over white rice. This mini-review ...
Cereal Chemistry
Background and Objectives In recent years, brown rice (BR) has become popular among the consumers due its nutritional excellence and health benefits as compared to polished or white rice. The objective of this review paper is to compare composition, health benefits, hurdles, shelf life, and potential ways to enhance the consumption of BR as compared to white rice.
Brown Rice Versus White Rice: Nutritional Quality, Potential Health
In addition, the removal of the outer bran layer during rice milling results in a loss of nutrients, dietary fiber, and bioactive components. Therefore, many studies were performed to investigate the potential health benefits for the consumption of whole brown rice (BR) grain in comparison to the milled or white rice (WR).
Rice
Scope & approach In this paper, we summarized the available literature on health-promoting and therapeutic activity of rice and rice biomolecules, and biomolecules, along with the scope of rice in pharmaceutical and food industry. In addition, we discussed the possible molecular mechanisms of action of the rice/rice part/biomolecules.
Review Article Brown Rice as Useful Nutritional Source
Abstract | Rice is widely consumed food entity in half of the world's population. Brown rice is unrefined, coarse and unpolished whole grain rice which is directly obtained by removing only husk. In Brown rice, the embryo may or may not be left undamaged depending upon the hulling process. Brown rice may become white rice when the bran layer is exposed of in the milling process. In present ...
Effect of storage on the nutritional and antioxidant properties of
Abstract The purpose of the present study is to evaluate the effect of storage time and temperature on the nutritional and antioxidant values of different varieties of brown rice. PARB approved indigenous Basmati varieties (Basmati 86, Basmati 515, Basmati super, Basmati super fine and Basmati kainat) were procured and initially tested for physicochemical parameters, including moisture, ash ...
Brown rice: Nutrition and health claims
Brown rice is a rice source of minerals and. dietary fibre that support the normal functioning of human body. This review covers nutritional composition and various biological. activities of brown ...
Ready to eat shelf-stable brown rice in pouches: effect of moisture
Despite several nutritional benefits of brown rice (BR) its consumption remains limited compared to white rice. Two of the major barriers to its consumption are long cooking time and limited shelf life. However, those two hurdles can be overcome through the development of shelf-stable BR pouches to create new ready-to-eat (RTE) products, a food category that is gaining important market shares ...
A Narrative Review on Rice Proteins: Current Scenario and Food
Despite this, lower solubility in water hinders the potential application of rice protein commercially. However, the industries and research communities possess an interest in developing more preferable processes for the extraction, enrichment, purification, and functionalization of rice protein.
Nutritional and functional properties of coloured rice varieties of
Rice is a major cereal food crop and staple food in most of the developing countries. India stands second in the production of rice next to China. Though almost 40,000 varieties of rice are said to exist, at present, only a few varieties are cultivated extensively, milled and polished. Even if white rice is consumed by most people around the world, some specialty rice cultivars are also grown ...
Effect of Brown Rice, White Rice, and Brown Rice with Legumes on Blood
Background: Improving the carbohydrate quality of the diet by replacing the common cereal staple white rice (WR) with brown rice (BR) could have beneficial effects on reducing the risk for diabetes and related complications. Hence we aimed to compare ...
Rice in health and nutrition
This reviews will cover some new research information on rice, rice bran and rice bran oil, especially in the biological activities and nutritional aspects to human.
Brown rice Research Papers
Innovative processing techniques for altering the physicochemical properties of wholegrain brown rice (Oryza sativa L.) - opportunities for enhancing food quality and health attributes Rice is a globally important staple consumed by billions of people, and recently there has been considerable interest in promoting the consumption of wholegrain brown rice (WBR) due to its obvious advantages ...
Research paper Long-term storability of rough rice and brown rice under
Abstract Two storage tests (4 years for Kirara 397 and 3 years for Yumepirika) were carried out to investigate long-term storability of rough rice and brown rice under three storage conditions. Super-low temperature storage (below ice point) maintained physiological properties and eating quality of rough rice and brown rice at levels similar to those of raw materials after 2 years of storage ...
Biological Functions and Activities of Rice Bran as a Functional
Rice bran (RB) is a nutrient-rich by-product of the rice milling process. It consists of pericarp, seed coat, nucellus, and aleurone layer. RB is a rich source of a protein, fat, dietary fibers, vitamins, minerals, and phytochemicals (mainly oryzanols and tocopherols), and is currently mostly used as animal feed.

Save citation to file

Add to My Bibliography

Brown Rice Versus White Rice: Nutritional Quality, Potential Health Benefits, Development of Food Products, and Preservation Technologies

Similar articles

Grants and funding

LinkOut - more resources

Ready to eat shelf-stable brown rice in pouches: effect of moisture content on product’s quality and stability

Cite this article

Similar content being viewed by others

Development of a functional rice bran cookie rich in γ-oryzanol

Sensory Evaluation, Shelflife and Nutritional Composition of Breadnut (Artocarpus camansi) Cookies

Introduction

Materials and methods

Brown rice moisture content

Brown rice texture

Brown rice grain morphology

Brown rice cooking loss

RTE brown rice poches production and microbial safety assessment

Water spatial distribution in pouches

Brown rice color in pouches

Brown rice texture in pouches

Statistical analysis

Results and discussion

RTE brown rice in pouches: characterization and long-term shelf-life stability

Texture analysis

Acknowledgements

Author information

Contributions

Corresponding author

Ethics declarations

Compliance with ethics requirements

Additional information

Rights and permissions

About this article

Share this article

Nutritional and functional properties of coloured rice varieties of South India: a review

Introduction

Origin and spread of rice

Importance of rice in India

Production and market demand for rice varieties

Rice varieties

The shelf life of rice

Structure of rice grain

Rice processing

Nutritional information

Phytochemical composition

Health benefits

Diabetes mellitus

Cardiovascular disease

Cholesterol

Hypertension

Medicinal uses of coloured rice

Traditional food and its importance

Availability of data and materials

Acknowledgements

Author information

Contributions

Corresponding author

Ethics declarations

Additional information

Rights and permissions

About this article

Share this article

Journal of Ethnic Foods

Rice in health and nutrition

Abstract and Figures

Article preview

Engineering in Agriculture, Environment and Food

Effects of small-scale storage on the cooking property and fatty acid profile of sea rice paddy

Changes in the chemical, physical, and sensory properties of rice according to its germination rate

Interleaved attention convolutional compression network: An effective data mining method for the fusion system of gas sensor and hyperspectral

Rice freshness determination during paddy storage based on solvent retention capacity

Biological Functions and Activities of Rice Bran as a Functional Ingredient: A Review

Weeraya Saphyakhajorn

Junaida Astina

Introduction

Nutritional Composition of RB

Structure of Functional Components of RB

Hemicellulose

Gamma-oryzanol