Rice Bran: From Waste to Nutritious Food Ingredients
by Bee Ling Tan Nutrients 2023, 15(11), 2503;
Rice (Oryza sativa L.) is a principal food for more than half of the world’s people. Rice is predominantly consumed as white rice, a refined grain that is produced during the rice milling process which removes the bran and germ and leaves the starchy endosperm.
Rice bran is a by-product produced from the rice milling process, which contains many bioactive compounds, for instance, phenolic compounds, tocotrienols, tocopherols, and γ-oryzanol.
These bioactive compounds are thought to protect against cancer, vascular disease, and type 2 diabetes. Extraction of rice bran oil also generates various by-products including rice bran wax, defatted rice bran, filtered cake, and rice acid oil, and some of them exert bioactive substances that could be utilized as functional food ingredients. However, rice bran is often utilized as animal feed or discarded as waste. Therefore, this review aimed to discuss the role of rice bran in metabolic ailments. The bioactive constituents and food product application of rice bran were also highlighted in this study. Collectively, a better understanding of the underlying molecular mechanism and the role of these bioactive compounds exerted in the rice bran would provide a useful approach for the food industry and prevent metabolic ailments.
Conclusions and Future Perspective
This review has shown clear evidence that intake of rice bran and its derived compounds may offer optimal health in in vitro and in vivo models as well as human studies. Therefore, rice bran holds great promise and may provide a useful approach to improving the immune system, alleviating chronic diseases, scavenging ROS, and decreasing inflammation. The broad spectrum of processes in which the antioxidants and bioactive compounds are involved suggests the protective role of rice bran and its derived compounds in the pathogenesis of several metabolic ailments. Indeed, rice bran exerts many bioactive constituents, for instance, phenolics, γ-aminobutyric acid (GABA), squalene, phytosterols, tocopherols, tocotrienols, and γ-oryzanol.
Due to the therapeutic potential, incorporating rice bran in food can contribute to the development of value-added foods or functional foods that currently are in high demand. Indeed, the addition of rice bran and its derived compounds has been utilized as supplements in many food matrices as well as improves the nutritional quality of processed food. Therefore, rice bran produced from the rice milling process or rice bran oil production may improve the economy of the rice-producing nations. However, there are several limitations in this study including (1) small sample size; (2) short duration of treatment; (3) different daily dosages of rice bran; and other factors such as the age of animals and subjects of the study. In addition, assessment of dose–response relationship and chronic diseases in clinical trials has not been evaluated. Collectively, this review may pave the way for the potential use of rice bran as a functional ingredient in various foods and to combat chronic diseases. The crucial role played by rice bran is nonetheless worth studying in-depth in long-term clinical trials.