Lipolysis and oxidative stability of soft ripened cheeses containing vegetable oils

In response to nutrition guidelines recommending a reduction in saturated f ats in human diets, the dairy industry has developed new products containin g unsaturated fats to satisfy the demand of the more health conscious consu mer. The fatty acid composition of milk, naturally rich in saturated fatty acids (SFA), can be modified either through genetic selection of dairy cows or by changing feed composition (Palmquist ct al. 1993), For example, a nu mber of dairy products including butter (Wood ct nl. 1975; Badings et al. 1 976), Gouda (Badings et al. 1976) and Cheddar (Wong et nl. 1973; Lightfield ct al. 1993) containing increased amounts of linoleic acid (18:2n-6) hare been made from the milk of cows given diets supplemented with unsaturated l ipids. However, dairy farmers would prefer to produce milk as cheaply as po ssible, leaving it to food technologists to modify milk components at the p ostproduction stage (Banks, 1987). Therefore, dairy products made from skin ? milk combined with a fat mixture could be attractive, but little informat ion is available on this type of modified product. One major problem relate d to the introduction of unsaturated fats into dairy products is the possib le alteration of their properties. Indeed, Badings (1970) reported that but ter enriched in polyunsaturated fatty acids (PUFA) has reduced flavour qual ity and shelf life. It is well known that PUFA are easily oxidized and can form undesirable compounds such as peroxides and aldehydes. Moreover, PUFA are more likely to be oxidized as free fatty acids (FFA) than to be integra ted into a triacylglycerol structure. Therefore, when a dairy product is ma de by recombining skim milk with unsaturated fats, such as the soft ripened cheese in this study, it is important to consider both lipolysis and oxida tive stability of the lipid fraction. This mas our objective in this study.