Oxidation of muscle phospholipids in relation to their fatty acid composition with emphasis on volatile compounds

Abstract

The impact of moderate changes of fatty acid (FA) composition of phospholipids (PL) on their oxidative stability and on volatile profiles remains largely unknown. PL of breast muscle of turkeys fed a diet containing 6% tallow, rapeseed oil or soya oil were purified and prepared as liposomes. After 24 h of incubation at 25 °C with iron/ascorbate, oxidation was quantified by measurement of thiobarbituric acid reactive substances (TBA-RS) and volatile compounds. TBA-RS level was the lowest (21.4 nmole eq MDA mg−1 PL) in PL from tallow-fed animals but was not significantly different (P > 0.05) in soya oil (30.9 nmole eq MDA mg−1 PL) and rapeseed oil (30.3 nmole eq MDA mg−1 PL) batches. ANOVA did not clearly distinguish between the three groups according to the quantities of individual volatiles except for Z,E-2,4-heptadienal. In contrast, principal component analysis (PCA) performed on standardised quantities of volatile compounds distinguished unambiguously the three groups. Axis 1 was positively correlated with volatile compounds arising from oxidation of n-6 fatty acids, and negatively with compounds of n-9 origin. Axis 2 was highly positively correlated with compounds from n-3 origin. Only a few compounds from each origin (n-6, n-3, n-9) had an atypical behaviour. A weak modification of the FA composition of PL led to concomitant modifications of the quantities of volatile compounds generated through oxidation, which were emphasised by multivariate analysis (PCA). © 1999 Society of Chemical Industry