Rice bran is the main source of rice bran oil, which contains lipids, proteins, tocopherols, and bioactive compounds. Rice bran is obtained from paddy rice in a multistage process, after harvest. The grains are submitted to the milling process, where, first, the kernel is separated from the hull (dehulling)
The main reason why rice bran has been largely limited to animal feed is that it quickly becomes rancid after milling, caused by lipase-mediated oxidation of rice bran lipids.49 Milling technology advances have now allowed for stabilized rice bran via cold storage, sun-drying, steaming, and expelling.50 Countries such as India, Thailand, and the United States have also started to use these stabilization processes to create rice bran oil. Although stabilization is a promising attribute for rice bran products, most of the rice-producing countries do not have this type of technology or current infrastructure. Thus, the immediate challenge is to develop rice bran stabilization methods in areas experiencing food insecurity, malnutrition, and high rates of mortality under the age of 5 years, such as many parts of Sub-Saharan Africa and Asia.
Rice bran has a shorter shelf-life compared to refined white rice due to increases in free fatty lipids during storage.51 If proper packaging and storage recommendations are followed, white rice can be stored for decades, compared to only about 1 year for the bran fraction. Advancing technology through extrusion cooking (a process of heating the food product under high pressure that results in reduced moisture content and a cooked and dried food product) has allowed for an extended shelf-life of rice bran.52 Another rice processing technique is parboiling, which deactivates the lipase and allows some minerals and water-soluble vitamins to leak from the bran to the endosperm, which increases the nutrient composition. However, antioxidants are also destroyed in this process, causing the nutrient profile to differ from that of heat-stabilized rice bran.4 The creation of technology that allows adequate stabilization will result in a longer shelf-life and create an opportunity to develop a market that utilizes rice bran as a common ingredient for human consumption.