Fatty Acid Compositions of Rice Lipid and their Changes during Storage

Abstract

Fatty acid composition of lipids from polished rice was studied by gas chromatography on the separated fractions, fat-by-hydrolysis, neutral fat, free fatty acid and phospholipid. After six months storage, fatty acids were released from neutral fat in the same proportion as they were combined in the neutral fat.

Effect of Superheated Steam Treatment on Enzymes Related to Lipid Oxidation of Brown Rice

“…The free unsaturated fatty acids thus produced are further converted into low-molecularweight volatile products via hydroperoxides generated by lipoxygenase and subsequent autoxidation. Researchers reported that some volatiles, especially n-hexanal, increase during storage (Yasumatsu and Moritaka, 1964;Yasumatsu et al, 1966;Shin et al, 1986;Zhou et al, 2002). These results suggest that the inactivation of lipase and lipoxygenase in brown rice suppresses the increase in stale flavor during storage.…”

“…The development of stale flavor has been studied in detail by several researchers, and the mechanism has been partially clarified (Yasumatsu and Moritaka, 1964;Yasumatsu et al, 1966;Aibara et al, 1986;Shin et al, 1986;Takano, 1993;Zhou et al, 2002). The proportion of lipid in brown rice is 2-3%, and most of the neutral lipids exist in the spherosomes of the embryo and aleurone cell, which are surrounded by a double monolayer of phospholipid (Aibara et al, 1986;Takano, 1993).…”

Changes in Rice Bran Lipids and Free Amino Acids during Storage

“…Many investigations about the stale flavor of rice have been carried out thus far,3"-'S) and Yasumatsu et al 9 ) have reported that free fatty acids were released from the neutral lipids during storage, and that the increase in their amounts resulted in the deterioration of rice flavor. In spite of intensive .efforts by many investigators, the detailed degradative process of the rice lipids remains obscure, especially the trigger of degradation, during storage.…”

Identification of gene for rice (Oryza sativa) seed lipoxygenase-3 involved in the generation of stale flavor and development of SNP markers for lipoxygenase-3 deficiency

“…Many researchers have reported that the free fatty acid content increases during rice storage and suggest that lipid degradation is responsible for deterioration during storage (Yasumatsu and Moritaka 1964, Takano 1993, Zhou et al 2002. Lipoxygenase (LOX) catalyzes the peroxidation of polyunsaturated fatty acids containing a 1,4-pentadiene structure, such as linoleic and linolenic acids, into conjugated hydroperoxy fatty acids.…”

“…Many compounds have been identified in raw and cooked rice or the bran fraction (Yasumatsu and Morikawa 1964, Tsugita et al 1983, Suzuki et al 1999, Zhou et al 2002. Researchers have reported that some volatile compounds, particularly hexanal, increase during storage (Yasumatsu andMoritaka 1964, Suzuki et al 1999). Since the amount of unsaturated fatty acids decreases in stored rice, Yasumatsu and Moritaka (1964) suggested that linoleic acid in rice is oxidized gradually during storage, thereby producing carbonyl compounds that induce a stale taste in rice.…”