Conjugated Linoleic Acid Contents in Cheeses of Different Compositions During Six Months of Ripening

The study deals with the effects of the origin of milk (cow, ewe, goat, at different proportions), seasonality, and ripening time on the contents of conjugated linoleic acid (CLA) in 224 samples of cheese. The sum of the cis9, trans11 and trans10, cis12 isomers was determined by GC-FID, after the extraction and methylation of the fatty acids of the samples, observing that the mean amount of CLA was 2.22, 2.72, and 3.54 mg/g of cheese, depending on the proportions of cow's, goat's, or ewe's milks, respectively. The contents in cow's, ewe's, and goat's milk, together with the ripening time and seasonality, were seen to have significant effects (P < 0.05) on the concentration of CLA. The Pearson correlation revealed an inverse correlation between the content of CLA and the % of cow's milk (r = -0.269, P < 0.01) and seasonality (r = -0.290, P < 0.01), and a direct correlation between CLA content and the % of ewe's milk (r = 0.312, P < 0.01) and the month of ripening (r = 0.188, P < 0.01).