Thermal denaturation of bacterial enzymes in milk
1995
Stepaniak, L. | Soerhaug, T. (Agricultural Univ. of Norway, Aes (Norway). Dept. of Food Science)
Extracellular proteinases, lipases and phospholipases C from many psychrotrophic Pseudomonas spp. and from some other psychrotrophic bacteria are stable at ultra-high temperatures (UHT range). These three enzymes may act synergistically in damaging the fat globule membrane. Because proteinases may cause gelation of UHT-sterilized milks, they have been investigated comprehensively. Both proteinases and lipases from many Pseudomonas spp. are heat-labile at temperatures between 50 and 65 degrees Celsius. General factors affecting the heat stability of bacterial enzymes, possibility for inactivation of proteinases and lipases from pseudomonads by low temperature treatment, heat stability of phosphatases from psychrotrophs, proteinases and aminopeptidases from lactic acid bacteria and heat stability of microbial beta-galactosidases are also reviewed. Interest in the use of bacterial enzymes which are both stable and active at high temperatures in dairy technology is, to date, limited.
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