Lipolysis mastitis

Milk from cows affected with mastitis alters the sensory quality of raw milk and cheese (Munro el al., 1984). Sensory defects are reported as increased rancidity and bitterness, factors which are consistent with higher levels of lipolysis and proteolysis (Ma et al., 2000). 

Mastitis and microbial contamination can also contribute to hydrolytic rancidity. In general, lipolysis caused by indigenous milk lipase accounts for most of the rancidity in raw milk and cream microbial lipolysis is of minor practical importance as little if any lipolysis occurs before the bacterial population reaches 106—107 cfu/ml (Suhren and Reichmuth, 1990). However, in stored milk products, lipolysis by microbial lipases is of greatest significance. Short shelf-life products such as pasteurized milks may be affected by pre-pasteurization lipolysis caused by milk lipase but may be affected by bacterial lipolysis at the end of their shelf-life (Deeth et al., 2002). 

The data of Gudding (1982) suggest that the elevation of FFAs may depend on the cause of mastitis, as relatively higher levels of FFAs were observed in milk from quarters infected with Staphylococcus aureus. When mastitis is induced experimentally by intramammary infusion of endotoxins or bacteria, the increases in FFAs correspond closely with the increases in SCC and other indices of mastitis (Salih and Anderson, 1979 Fitz-Gerald et al., 1981 Ma et al., 2000). Murphy et al. (1989) concluded that the increased lipolysis in mastitic milk is due to increased susceptibility of the milk fat. 

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