Observations on Milk Protease

The milk proteinase system

“…This review complements previously published reviews on milk enzymes by Harper, Robertson & Gould (1960), Zittle (1964), Shahani (1966) and Shahani et al (1973). It also supplements the information on proteinase to be found in more general reports (Jenness & Patton, 1959;Groves 1971;Johnson, 1974;Alais, 1975;Brunner, 1977).…”

“…It is assumed also to be present in goat's milk (Zittle & Ouster, 1963). Its activity varies in individual milks (Harper et al 1960;Kiermeier & Semper, 1960a;Dulley, 1972 andNoomen, 1975). Moreover, according to Kiermeier & Semper (19606), it reaches a maximum immediately following calving, and subsequently decreases rapidly to a fifth of its maximum value in bovine milk.…”

“…Although milk proteinase was previously deemed not to have serious effects in dairy products (Harper et al 1960;Bingham & Zittle, 1963;Nakai, Wilson & Herreid, 1964), it is now considered to be an important factor (Nutting, 1970;Andrews, 1975;Alais, 1975).…”

Indigenous enzymes in milk: Overview and historical aspects—Part 1

“…Warner and Polis (1945) thought that the proteinase might be indigenous but did not rule out a bacterial origin. Using aseptically drawn, low-bacterial count milk with added antibiotics, Harper, Robertson, and Gould (1960) showed that milk does contain an indigenous proteinase(s), but the level was considered to be so low as to be insignificant.…”

Milk alkaline proteinase

“…Warner & Polis (1945) reported a low level of proteolytic activity associated with acid casein which caused a decrease in the viscosity of casein solutions during storage and an increase in pH 4-6-soluble N. These workers were unsure whether the proteinase(s) was indigenous or of bacterial origin. However, Harper et al (1960), using aseptically produced, low-bacterial count milk containing antibiotics, showed that milk did contain an indigenous proteinase(s) but the level was considered so low as to be insignificant.…”