ABSTRACT
Phenolics are phytochemicals extensively distributed among plants that have been receiving great deal of attention for their functionality. Rice bran is a good source of phenolics, especially hydroxycinnamates. Although chemicals are commonly employed to isolate phenolics, the use of physical treatments such as sonication is still limited. This study was conducted to optimize a procedure to isolate phenolics from rice bran using sonication as a preextraction treatment. Sonication was optimized by varying output, time, and temperature. Extraction was optimized by varying solvent, extraction time, temperature, and sample-to-solvent ratio. After an optimum procedure was established, HPLC analyses were conducted to identify and quantify the major individual phenolic acids extracted. The optimum conditions for extracting phenolics from rice bran were sonication with water (1:100 sample-to-solvent ratio) for 1 min; output intensity of 10; holding at ambient temperature; and autoclave treatment for 20 min at 121°C. This procedure extracted 8.85 ± 0.18 mg of phenolics/g of dried rice bran. Benzoic, p-coumaric, and trans-ferulic acids were the major phenolics identified in the extract. The proposed procedure will be valuable in obtaining phenolics for increasing product functionality such as lipid oxidation inhibitors in food systems.
