NONPOLAR-VOLATILE LIPIDS FROM SOY PROTEIN ISOLATES AND HEXANE-DEFATTED FLAKES

Lipid extracts from two samples of commercial soy protein isolates (SP I) and two samples of commercial hexane-defatted flakes were fractiona ted by silicic acid-column chromatography. The material eluted with 10 0% chloroform was collected, further fractionated by silica solid-phas e extractions, and analyzed by gas chromatography-mass spectroscopy by using mass spectra, retention times of authentic standards, and Kovat s indices for identification. Thirty-eight compounds were identified a nd quantitated in the lipid fractions from soy protein isolates (SPI); 23 of these are reported for the first time as components of SPI. An additional 13 compounds are re; ported for the first time as component s of hexane-defatted soybean flakes. The major classes of compounds re ported for the first time associated with SPI include: butyl, methyl, and ethyl esters of fatty acids; phenols, diphenyls and phenyl esters; and abietic acid derivatives. Dehydroabietinal at 0.180 to 0.191 ppm of the protein isolates was the most abundant aldehyde in the SPI lipi d extracts The third most abundant aldehyde found in SPI after dehydro abietinal and hexanal was 2-butyl-2-octenal (0.065 to 0.086 ppm). Dehy droabietic acid methyl ester was present in SPI (0.309 to 0.459 ppm) D ehydroabietene (0.628 ppm) and abietatriene (0.396 ppm) were tentative ly identified in one sample of hexane-defatted flakes.