Cellulase-assisted extraction of phenolic compounds from rice bran (Oryza sativa L.): process optimization and characterization

This study investigated the improvement in the extraction of antioxidant phenolic compounds from a by-product of the food industry, rice bran, using hydrolytic enzymes. To this purpose, the optimization process of obtaining these compounds was carried out, as well as chemical characterization of the rice bran extracts by high performance liquid chromatography (HPLC) and the determination of their antioxidant activity. First, the parameters that affect the extraction process, such as the type on enzyme, temperature and pH of the solution, the extraction time and the enzyme concentration used for obtaining phenolic compounds were studied. The influence of these factors was later examined by characterizing the compounds obtained by HPLC, and the antioxidant activity of the extracts. The optimum conditions were: temperature 35 °C, pH 3.0 solution, extraction time 4 hours and cellulase content of 1.0%. In these conditions, extraction yield ranged from 3.45 ± 0.9 mg ferulic acid/100 g rice bran (without cellulase) to 14.3 ± 2.2 mg ferulic acid/100 g rice bran (with 1 % cellulase). Finally, the increases in antioxidant activity are lighter than those produced in the concentration of phenolic compounds, so we concluded that the enhancement in bioactivity is more limited when cellulase enzyme-assisted extractions were carried out in rice bran.