Effects of cooking process on antioxidative and anti‐inflammatory activities of black rice extracts (830.4)

Abstract

Black rice (Oryza sativa L. indica), a special rice cultivar widely consumed in Asia countries, contains high levels of anthocyanins and are known to possess health‐promoting effects. This study was aimed at investigating the effects of cooking processes on total anthocyanin content as well as antioxidant and anti‐inflammatory activities of raw and cooked black rice. The rice was soaked and washed for 1‐3 times followed by cooking in a rice cooker. After freeze‐dried, the rice was extracted with acidified methanol, and the in vitro antioxidative activities as well as the anti‐inflammatory properties of the extract were determined. The results indicated that the cooking process significantly decreased total anthocyanin contents in the rice, while the washing time had no effects on the anthocyanin contents in cooked rice. Correspondingly, raw rice showed a higher scavenging activity as demonstrated from DPPH assay, whereas the ferric reducing antioxidant power (FRAP) showed no difference among extracts. Besides, all extracts inhibited the production of nitric oxide (NO) and TNF‐α in lipopolysaccharide (LPS‐)‐activated RAW 264.7 macrophages, but no effects on stimulated interleukin (IL)‐6 and IL‐1β. In summary, black rice, both raw and cooked, possessed in vitro antioxidative and anti‐inflammatory activities by possessing DPPH scavenging activity and by inhibiting activated NO and TNF‐α production, respectively, and cooking process decreased the anthocyanin contents and reduced the potency of these activities.