Abstract
The compositional and quantitative changes of fatty acids, tocopherols (Toc) and sterols in soybean seed lipids and/or seeds from 25 to 75 days after flowering were investigated. The fatty acid and Toc compositions of lipids were determined by gas and high-performance liquid chromatographies. Sterol compositions in unsaponifiable matter were determined by using preparative thin-layer chromatography followed by gas chromatography.
Weights of soybean seeds increased rapidly until 45 days after flowering, and the lipids accumulated at a steady rate up to 50 days after flowering. The highest concentration of unsaponifiable matter, sterols and chlorophyll in lipids were found at an early stage after flowering, and decreased steadily. The percentages of campe-, stigma- and β-sitosterol in 4-demethylsterol were 20.2, 13.6 and 66.1, respectively, in the immature seed lipids (25 days after flowering). But the percentage of β-sitosterol decreased markedly, whereas campe- and stigmasterol increased up to maturity. The main Tac in seed lipids were α-, γ- and δ-Toc, and α-, β- and δ-Toc showed marked increase up to maturlty, whereas γ-Toc contents in lipids were almost constant during maturation of seed. Generally, the percentage of linoleic acid in total lipids and triacylglycerol increased up to maturity, but the percentages of linolenic and palmitic acids decreased. The percentage of oleic acid in lipids reached a maximum at 45 days after flowering, and decreased thereafter.
