Production of Desirable Flavor

Lipolysis plays an important role in providing the characteristic flavor of many milk products. In particular, the ripening of most cheese varieties is accompanied by lipolysis due to microorganisms or to added enzyme preparations, and, in raw milk cheese, to the milk LPL. Lipolysis is not extensive, but is more pronounced in some cheeses (e.g., blue-veined and hard Italian varieties), than in others. Excessive lipolysis renders the cheese unacceptable (Fox and Law, 1991 Gripon et al., 1991). 

In some mold-ripened cheeses, a very high FFA content (up to 25% of total fatty acids Gripon, 1987) is acceptable [e.g., 66 000 mg/kg for Blue cheese (Horwood et al., 1981) compared to 4000 mg/kg for good quality Cheddar (Bills and Day, 1964)]. High levels of butyric acid characterise Italian hard cheeses and certain pickled cheeses (Fox and Guinee, 1987), [e.g., up to 520 mg/kg for Greek Feta (Horwood et al., 1981) and 3000 mg/ kg for Romano (Woo and Lindsay, 1984)]. An imbalance in flavor constituents can, nevertheless, lead to undesirably rancid or goaty (C4 o-C8 0) or soapy (Cio o-Ci2 o) flavors in these cheeses (Woo and Lindsay, 1984). 

Flavor preparations typical of particular varieties of cheese can be produced with the aid of lipases of appropriate specificities (Kilara, 1985). Such flavors are used in processed cheeses, dips and spreads (Jolly and Kosikowski, 1975b). Controlled lipolysis of milk fat is also used to produce creamy and buttery flavors for bakery and cereal products, confectionery (milk chocolate, fudge), coffee whiteners, and other imitation dairy products (Arnold et al., 1975 Fox, 1980 Kilara, 1985). 

Absorption of fat in the newborn, and particularly in premature infants, is much less efficient than in adults due to the relatively low output of lipase and bile salts from the pancreas of the infant. Intragastric lipolysis by milk BSSL and lingual or salivary lipases, the secretion of which is stimulated by suckling, appears to augment the pancreatic lipase system in the newborn (Hamosh, 1979 Hernell and Blackberg, 1994). 

Although LPL activity is commonly present in the milk of mammalian species, its role in the digestion of milk fat by the young animal has not been demonstrated (Olivecrona et al., 2003). Olivecrona et al. (2003) speculated that LPL may serve an auxiliary role by binding milk fat globules to the mucosa, binding to intestinal cell surfaces and transferring lipids into the cells these roles may not be dependent on the hydrolytic activity of the enzyme. 

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Some reviews (41, 52-54) are available. The positive aspects are found in the production of desirable flavors and aromas. Fujimaki and Kurata ( 55) listed aldehydes and pyrazines, volatile compounds produced by heating amino acids with carbonyl compounds, isovaleraldehyde produced by reaction of leucine with carbonyl compounds (aldehydes,... 

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