Lipolysis flavor defect

Consumer acceptance of milk is strongly determined by its sensory characteristics. The development of off-flavor in milk as a result of lipolysis can reduce the quality of milk. The enzymatic release, by milk lipase, of free fatty acids (FFA) from triglycerides causes a flavor defect in milk described as rancid . Triglycerides in milk contain both long chain and short chain fatty acids, which are released at random by milk lipase. The short chains FFA, like butyric acid, are responsible for the off-flavor. 

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... 

While flavor defects are the most likely result of lipolysis in dairy products, several other practical problems may arise from an elevated level of FFAs. The most common of these is lack of foaming of pasteurised milk for cappuccino-style coffee (IDF, 1987). Reduced efficiency of skimming of raw milk and reduced churning efficiency in cream may be associated with lipolysis, especially where excessive agitation or pumping causes damage to the milk fat globule membrane. 

The difficulty in relating rancid flavors in butter to FFA content arises because the short-chain acids, C4 o and C6 o, which are the most flavorsome (McDaniel et al., 1969), are water-soluble and hence are mostly lost in the buttermilk and wash water during the manufacture of butter. For this reason, even butter made from cream with an ADV as high as 2.4 meq/lOOg fat may show little defect while on the other hand, butter with quite a low ADV can be rancid, particularly if lipolysis occurs after manufacture (Deeth et al., 1979 Woo and Lindsay, 1980). 

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