Extraction of brown rice extract and application in refined palm olein during accelerated storage

This research aimed to determine optimum condition of the phenolic compounds from brown rice extract from Sung Yod Phatthalung and to determine their applications as an antioxidant in refined palm olein. Brown rice was extracted with solvent concentration (40 - 80% ethanol, vv^-1), pH (2 - 8) and extraction time (5 - 60 min). Total phenolic content and antioxidant activities as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) of brown rice extract were measured. The optimum conditions were as follows: ethanol concentration, 60% (vv^-1); pH 6 and extraction time, 25 min. Under the above-mentioned conditions, the experimental total phenolic content and DPPH of brown rice was 1.30 mg ferulic acid equivalents/g of dry sample and 86.55%, respectively. The oxidation properties (peroxide value, PV and thiobarbutitutic acid reactive substance, TBARS) of antioxidant in refined palm oil were compared with other synthetic antioxidants (butylated hydroxyanisole, BHA and butylated hydroxytoluene, BHT) at different concentration. It has been observed that the highest efficiency of BHT, followed by brown rice extract, BHA and control. The results revealed that the brown rice extract to be a potential antioxidant for stabilization of refined palm olein.