Extraction of health-promoting oil from bran of Philippine rice varieties

Bran is a major by-product of rice processing. Although available in abundant amount, the utilization of rice bran in the Philippines is still limited. However, it is recognized as a good source of edible and healthful products such as rice bran oil (RBO). It is considered the world's healthiest oil because it is loaded with beneficial components such as phenolic compounds and vitamin E derivatives, which are powerful antioxidants. Although very popular in many countries, the tremendous health and market potentials of RBO in the food, pharmaceutical, and cosmetic industries in the Philippines are yet to be realized. This study was conducted to optimize the solvent extraction for RBO production and the refining or purification of oil. Bran samples were collected from pure rice varieties such as NSIC Rc160, and mixed rice varieties from local millers. Rice bran is prone to hydrolytic and oxidative rancidity due to its high oil content and the presence of several active enzymes. Therefore, rice bran must first be stabilized before oil extraction. Cold treatment, autoclave, dry heat, and steam heat were evaluated for this purpose. Based on lipase activity and changes in free fatty acid content, steam heating was identified to be the most effective method in stabilizing rice bran. Proximate composition of the bran samples was also determined. RBO was then extracted from rice bran using hexane as solvent. Different parameters such as bran and solvent ratio, time of extraction, and extraction temperature were evaluated. The best combination includes 1:3 bran:hexane ratio, 3-hr extraction time, and ambient temperature. In refining the crude oil, both chemical and physical refining methods were evaluated. The different steps involved in refining such as degumming, neutralization, bleaching, winterization, and deodorization were optimized. This study indicates that with optimum extraction conditions, RBO can be efficiently obtained from local rice.