Autoxidation of milk fat

Prolonged storage of ice cream and exposure to severe temperature fluctuation commonly causes shrinkage, which is a defect due to partial thawing and loss of moisture and air. An additional defect common to ice cream after prolonged storage is oxidized flavor, which is caused by autoxidation of milk fat. This defect is especially important in ice cream products that contain frozen or dried milk ingredients. 

Beaulieu, A.D. and Palmquist, D.L. 1995. Differential effects of high fat diets on fatty acid composition in miUc of Jersey and Holstein cows, J. Dairy Set, 78, 1336-1344. Chen, Z.Y. and Nawar, W.W. 1991. Role of milk fat globule membrane in autoxidation of milk fat, J. Food ScL, 56(2), 398-426. 

Day, E. A. and Lillard, D. A. 1960. Autoxidation of milk lipids. I. Identification of volatile monocarbonyl compounds from autoxidized milk fat. J. Dairy Sci. 43, 585-597. 

In addition to positive aspects, numerous flavor and textural defects may be associated with the fat phase of ice cream. Such flavor defects are usually related to either autoxidation of the fat, resulting in oxidized flavors (cardboardy, painty, metallic) or, especially in the case of milk-fat, lipolysis of free fatty acids from triglycerides by the action of lipases (referred to as hydrolytic rancidity). A significant content of free butyric acid gives rise to very undesirable rancid flavors. These defects tend to be present in the raw ingredients used in ice cream manufacture, rather than promoted by the ice cream manufacturing process itself. However, processing... 

It has been extensively shown that pecific feeding regimes can increase the concentrations of boh polyunsaturated lipids and pro-oxidative metal pedes, which boh make he milk more prone to autoxidation (6 7 8 9 10). Thus several studies have been perfomted to limit autoxidation in milk through optimized feeding (II 12). Moreover, numerous studies have shown that antioxidants in he feed are transferred to he milk and hereby improve he oxidative stability of milk. It has been reported hat increasing concentrations of dietary vitamin E can effectively reduce he intensity of oxidized flavor in milk (13 14). Recent studies confirm hat a-tocopherol protects milk fat from oxidation (IS). In contrast, earlier studies have not been able to show hat... 

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