Antioxidant Activity and Taste-active Component Distribution in the Bran Layer of Rice Grain

Abstract

Rice bran contains a higher level of bioactive and taste-active components than polished rice. The outer (inedible bran) layer of rice grains will be fractionated and analyzed to determine the distribution pattern of the various compounds in the bran layer. The phenol content, 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, and lipophilic oxygen radical absorbance capacity (ORAC) were higher in fractions obtained from the outer layer, decreasing upon moving inwards. The hydrophilic ORAC was the highest in the second most outer layer. Although the concentrations of sucrose, umami amino acids, sweet amino acids, bitter amino acids, and gamma amino butyric acid were higher in the inner fractions of the bran layer close to the outside of the polished rice, their distribution patterns differed slightly. The obtained results indicated that the antioxidant and taste-active compounds were localized in different portions of the bran layer.