Changes in rice bran lipids and free amino acids during storage.

Abstract

The lipids of rice in storage, mainly triacylglycerols which accumulate in spherosomes, began to decrease after 6 months of storage, while the level of free fatty acids gradually increased from the early stage of storage. Furthermore, phosphatidylcholine, which is one of the major constituents of the spherosome membrane, altered to phosphatidic acid after 6 months of storage, indicating that the spherosome membrane underwent deterioration. It is suggested from these results that the spherosome membrane becomes leaky due to the alteration of its phospholipid composition, and consequently triacylglycerols that ooze out of the spherosomes, are degraded to free fatty acids and glycerol through mono- or di-acylglycerols. After 6 months of storage, degradation of the rice bran lipids proceeded rapidly by the accompanying deterioration of the other constituents.