Phenolic retention of brown rice after extrusion with mesophilic α-amylase

Based on the results of phenolic retention of brown rice treated by extrusion with thermostable alpha-amylase (ETA), this work investigated the phenolic retention of brown rice after extrusion with mesophilic alpha-amylase (EMA). Similarly, EMA significantly increased phenolic retention of brown rice with the increasing enzyme level, and the phenolic retention was positively correlated with reducing sugars. However, brown rice treated by EMA had higher retention rate of free phenolic content, free antioxidant activity, and total identified free phenolic acids than that treated by ETA at different enzyme levels, although the corresponding reducing sugars produced by EMA were lower than by ETA. These results indicated that the extrusion temperature had greater effect on the phenolic retention than enzymatic hydrolysis during enzymatic extrusion. In addition, brown rice treated by EMA with 0.5% enzyme had a high retention of free flavonoids at 72.4%. Therefore, EMA might be a better processing technology for brown rice to improve its nutrition.