Post-harvest drying of fresh rice grain and its effects on deterioration of lipids during storage.

Abstract

Fresh rice grains were dried after harvest by three different drying methods (natural, dehumidified-air, and heated-air drying), and changes in the tipid contents and lipid metabolizing enzyme activities were investigated after storage at 4°C and ambient temperature. The contents of triacylglycerols and phospholipids in the grains decreased after 15 months storage at ambient temperature. In the case of heated-air drying at 50°C, the decrease was the largest. However, marked changes were not found in the grains stored at 4°C. Electron micrographs of the spherosome particles showed that some deformation and fusion occurred in the grains with the heated-air drying at 50 °C after 6 and 12 months of storage. However, such changes in spherosomes were distinctly suppressed in the grains dried by the dehumidified-air dryer at 30 °C. It is noted from this evidence that the conditions of post-harvest drying of fresh rice grains markedly influence the deterioration of rice grains in storage.