Levels of Conjugated Linoleic Acid (CLA) in Ewe Milk and Pecorino Cheese: Effect of Season, Feed and Cheese Aging
Progress in Nutrition
Conjugated Linoleic Acid (CLA) is a fatty acid of animal origin, which has shown anticarcinogenic properties in a number of experiments with rodents. CLA is present in remarkable quantity in foods of ruminant origin. Among these, ewe milk products like Pecorino cheese seem to be particularly rich in CLA. A study was carried out to investigate the relationship between CLA content of ewe milk used for Pecorino cheese production and season and diet. Moreover we verified the effect of cheese production and aging. Fat content, fatty acid composition and CLA concentration were determined on bulk milk samples taken from grazing ewes in different seasons: spring (May), summer (August), autumn (October) and fed with hay in winter (February). Pastures and hay were sampled and analysed for nutrients content and individual fatty acids. Pecorino cheeses produced from the tested milk were sampled after 1, 3 and 5 months of aging and were analysed for fat content, fatty acids composition and CLA concentration. In milk, c9,t11 CLA concentration was higher in spring samples (14.53 mg/g fat) and gradually decreased from summer to winter, when the lowest values were found (9.20 mg/g fat). c9,t11 CLA content was negatively correlated with the concentration of crude fiber, ADF and NDE c9,t11 CLA concentration in cheeses ranged from 6.29 mg/g fat to 14.52 mg/g fat and seemed to decrease slowly after cheese production, but no regular trend was observed during aging. Only cheeses made with winter milk showed significantly lower CLA concentrations after 3 and 5 months of aging. Fatty acid composition of milk showed a significant variation of saturated fatty acid concentrations that increased from spring to winter. Polyunsaturated fatty acids (PUFA) decreased from spring to winter, in particular 18:3ω3. These results reflected the content of PUFA in the feed. The results showed that diet is the main factor influencing CLA concentration, in particular fiber quality. Pasture feeding enhanced CLA levels in milk, while consumption of hay during winter decreased CLA levels. Milk processing and cheese aging had a negative effect on CLA concentration.
A. Prandini, F. Conti, D.E. Diaz, G. Piva. 2004. Levels of conjugated linoleic acid (CLA) in ewe milk and Pecorino cheese: effect of season, feed and cheese aging Progress in Nutrition 6: 115-121.