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Unlocking Rice Bran’s Healing Potential: Functional Food for Nutritional Security

NandLal Meena*1,2, Maheshwari1, Ajeet Singh Dhaka1, Muzaffar Hasan3, Arti Kumari1, Rakesh Bhardwaj2, Aruna Tyagi1,

1 ICAR-Indian Institute of Agricultural Research, New Delhi-110012
2 ICAR-National Bureau of Plant Genetic Resources, New Delhi-110012
3 ICAR-Central Institute of Agricultural Engineering, Bhopal-462038
*Corresponding author mail ID –nd.iari09@gmail.com

Rice bran and its nutritional composition

Rice,also known as (Oryza sativa L.) is the second most important staple food after corn globally. It is a significant source of carbohydrates, protein, vitamins, and minerals. Undoubtedly, rice holds immense influence in Asia, where its cultivation and consumption have shaped societies for millennia. According to 2021-22 statistics from FAOSTAT, global polished rice production reached a staggering 507.90 million metric tons, emphasizing the crop’s pivotal role in feeding the world’s population.The rice milling process involves two fundamental procedures. The first one is the removal of the husk to produce brown rice, while the second one is the removal of the bran layer from brown rice, resulting in polished (or white) rice.

The milling process involves eliminating the germ and a part of the endosperm, resulting in broken kernels and powdery substances. (Fig. 1). The milling process produces a primary product, which is milled rice, and several secondary products, including the husk, germ, bran layer, and broken kernels. Ideally, the milling process should yield 20% husk, 8-12% bran (based on the degree of milling), and 68-72% milled or white rice (depending on the variety). It is worth noting that rice by-products contain more nutrients than polished rice. The following sentence provides an overview of the composition of various rice by-products: Brown rice contains the highest concentration of non-starch components in its bran fraction, while milled rice (endosperm) is richest in starch (Table 1).

The embryo, aleurone layer, and sub-aleurone layer contain a high concentration of lipid bodies, resulting in the highest energy level in bran, followed by brown rice and then milled rice.
Brown rice contains more protein compared to milled rice due to the presence of higher protein levels in its bran. Brown rice also has higher levels of crude fat, crude ash, crude fiber, and total dietary fiber, which are concentrated in the bran fraction.

Health benefits of rice bran
Rice bran, constitutes not more than 9% of the total weight, yet it has sparked interest among researchers due to its great nutritional value, bioactive compounds and substantial health advantages (Fig. 2). Studies have also unveiled the effective role of rice bran to counter various diseases like cancer, tumor, cardiovascular diseases hypocholesterolemia, hypo-allergenicity and hypolipidemic effects (Park et al., 2017).Rice bran contains tocols and oryzanols as its primary antioxidants, with oryzanols exhibiting 10 times more antioxidant activity than tocopherols, and tocotrienols demonstrating 40-60 times greater antioxidant power than tocopherols. In addition to being a vital component of baby food, the protein found in rice bran is devoid of gluten, soybeans, and lactose, making it a non-allergic and healthier food supplement (Zheng et al., 2019). Plant sterols present in rice bran may provide nutritional assistance in the treatment of conditions such as alopecia, hypercholesterolemia, diabetes, hepatitis C, herpes, allergies, chronic tiredness etc. (Sharif et al., 2014). Rice bran is not only effective in reducing low-density lipoprotein, commonly referred to as “bad” cholesterol, but it also increases high-density lipoprotein, or “good” cholesterol, and lowers overall serum cholesterol levels. The nutraceuticals derived from rice bran’s soluble fiber portions are effective against type I and type II diabetes (Qureshi et al., 2002). A diet high in heat-stabilized rice bran benefits bacterial variety and richness in the gut, supports microbial metabolism, modifies stool metabolite profiles, and helps colorectal cancer survivors avoid chemotherapy (Sheflin et al., 2017). The dietary fiber in rice bran eliminates pollutants, facilitates stoma passage, and maintains an ideal pH, thereby avoiding colon cancer. Fermented rice bran and its extracts have recently been found very effective in reducing inflammation. Tocotrienols in bran oil reduces the inflammatory milieu in the pancreas, as well as inhibit tumor formation (Punia et al., 2021). Lutein and zeaxanthin in rice bran are responsible for improved vision and a reduced risk of cataracts. Rice bran has vitamin E and inositol hexaphosphate, which help to remove calcium from the blood and bones (Das et al., 2014). This keeps calcium from forming kidney stones.

Potential applications of rice bran in food industry
Each year, approximately 90% of the rice bran produced globally is utilized as a cost-effective feedstock for cattle and poultry, while the remaining portion is employed for the extraction of rice bran oil. Nowadays, people are increasingly focused on their personal health and nutrition, and are more conscious about what they eat.

Rice bran, which is highly nutritious, is commonly used as a food additive (Fig. 2). Rice bran added to supplement to foods, could be a potential technique for increasing overall nutritional value, and food experts are working on rice bran-added products.Rice bran protein, specifically deamidated protein hydrolysates, is rich in asparagine and glutamine. These compounds can be used to improve the flavor of soups, sauces, and poultry dishes. A freshly manufactured rice bran enriched biscuit with 10% rice bran protein concentrate proved more gratifying than a non-rice bran biscuit (Yadav et al., 2011).

Chicken coated with stabilized rice bran fibre prior to frying, it tends to absorb less fat. Additionally, the natural fat present in rice bran fibre can help carry flavours, enhancing the taste of the chicken. Rice bran oil sausages have desirable textural attributes as well as nutritional profile as compared to unsaturated fatty acids. Rice bran hemicellulose and defatted rice bran preparations possess significant potential in the food industry, especially in the development of functional foods such as functional bakery products (Hu et al., 2009). In the food industry, rice bran finds its application in the production of meat emulsions and batter mixes. (Tuncel et al., 2014). Supplementation of rice bran for development of functional foodis also implemented for development of various products including pasta enriched with anthocyanin-rich black rice bran (Sethi et al., 2020), rice bran enriched porridge (Calvo-Castro et al., 2019), and biscuits with soluble dietary fiber from defatted rice bran (Jia et al., 2020). Rice bran is ideal for producing baked goods such as muffins, cookies, crackers, breads, pancakes, and pastries due to its protein content. By adding rice bran to bread and cookies, the amount of lysine, protein, and dietary fiber rose according to the amount of supplementation. The content of nutritional parameters, comprising protein efficiency ratio (PER), biological value, and net protein utilization (NPU), was found to be higher in chapters that contained processed rice bran.

Conclusion and recommendations
Rice bran possesses significant potential to be transformed into nutritious food items, thereby contributing to food security in the country. Numerous health benefits are associated with consuming rice bran, and conducting in vivo studies can help establish a comprehensive database that promotes nutritional security. Although a comparative analysis of the shelf life achieved through different stabilization techniques has not been conducted at this time, it is an intriguing area of research that could lead to more effective supplementation of rice bran in various food systems. By investigating the shelf life of rice bran stabilized with different techniques, researchers can identify the most suitable method for enhancing the shelf life of rice bran and predict its potential for use in different food systems. This could ultimately result in the development of healthier and more sustainable food products. Though rice bran has the potential to improve health outcomes, studies on the effects of its daily consumption are lacking.To determine the health benefits of rice bran protein and its hydrolysates, additional research on both animal models and human subjects is necessary. Furthermore, future research should focus on developing RBP-enriched food products that are healthy and acceptable to consumers at an economical cost.

References
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