Effect of triacylglycerol composition and structures on oxidative stability of oils from selected soybean germplasm

Abstract

The oxidative stability of soybean oil triacylglycerols was studied with respect to composition and structure. Crude soybean oils of various fatty acid and triacylglycerol composition, hexane~extracted from ground beans, were chromatographed to remove non-triacylglycerol components. Purified triacylglycerols were oxidized at 60~ in air, in the dark. The oxidative stability or resistance of the substrate to reaction with oxygen was measured by determination of peroxide value and headspace analysis of volatiles of the oxidized triacylglycerols (at less than 1% oxidation). The correlation coefficients (r) for rates of peroxide formation (r = 0.85) and total headspace volatiles (r = 0.87) were related positively to oxidizability. Rate of peroxide formation showed a positive correlation with average number of double bonds (r = 0.81), linoleic acid (r = 0.63), linolenic acid (r = 0.85). Rate of peroxide formation also showed a positive correlation with linoleic acid (r = 0.72) at the 2-position of the glycerol moiety. A negative correlation was observed between rate of peroxide formation and oleic acid (r = --0.82). Resistance of soybean triacylglycerols to reaction with oxygen was decreased by iinolenic (r = 0.87) and increased by oleic acid (r = --0.76)-eontalning triacylglycerols. Volatile formation was increased by increased concentration of linolenic acid at exterior glycerol carbons 1,3 and by linoleic acid at the interior carbon 2. Headspace analysis of volatiles and highperformance liquid chromatography of hydroperoxides indicated that as oxidation proceeded there was a slight decrease in the linolenic acid-derived hydroperoxides and an increase in the linoleic acid~ierived hydroperoxides. The oxidative stability of soybean oil triacylglycerols with respect to composition and structure is of interest to the development of soybean varieties with oils of improved odor and flavor stability.

HPLC Retention Behavior of Triacylglycerols Extracted from Soybean Oil by Supercritical CO2

“…Furthermore, the levels of LnLnLn (trilinolenoin), LnLnL (dilinolenolinolein), LnLO (linolenolinoleoolein), PLP (linoleodipalmitin), OOP (dioleopalmitin), OOO (triolein) and SOP (stearinoleopalmitin) were relatively low (less than 4 %). Similar data for soybean oil TAGs composition was reported previously [32][33][34] with specific differences due to use of different soybean cultivars.…”

Fatty acid composition of oil obtained from soybeans by extraction with supercritical carbon dioxide

“…Higher concentrations of linoleic, linolenic, and palmitic acids were obtained in previously collected fractions, whereas the concentrations of oleic and stearic acids increased in the fractions collected later. A similar trend in Neff et al (1992), Holčapek et al (2003), Sudar et al (2003), with specific differences due to the use of different soybean cultivars.…”

Production of Biodiesel with Seed Soybean and Supercritical Ethanol

“…This composition is considered of good quality. The presence of higher levels of the esters linoleate (C18:2) and linolenate (C18:3) compared to other esters gives favorable oxidation characteristics because the greater the presence of instaurations (double bonds), easier the oxidation of fatty acid ethyl ester [11] [12].…”