Regional difference and localization of D- and L-amino acids contents in brown rice for sake brewing

Abstract

d-Amino acids are widely detected in various organisms and foods and expected to have physiological functions for human. We measured all of the d- and L-amino acids in 48 kinds of brown rice for sake brewing using HPLC. We found that the almost all brown rice contained the d-amino acid forms of Ala, Arg, Asn, Asp, Glu, Gln, His, Ser, Val. Asp and Glu. d-Ala was detected only in brown rice produced in Hyogo, Hiroshima, Kochi, and Fukui Prefecture. The d-Ser concentration was relatively high in brown rice produced in Yamagata, and Tokushima Prefecture. d-Val was detected in brown rice produced in Hokkaido and Iwate Prefecture but not in Kochi and Kagawa Prefecture. d-Asp was detected only in brown rice but not in the 70%, 60%, and 50% polished rice. These results suggested that d-Asp existed around the center of the brown rice, and other d-amino acids existed near the surface of the brown rice. Accordingly, d-amino acid contents of brown rice for sake brewing are different significantly depend on the production area and the polishing ratio.