Partial characterization of cheese-ripening proteinases produced by the yeast<i>Kluyveromyces lactis</i>

Abstract

SUMMARY An extract of Kluyveromyces lactis 416 and a β-galactosidase preparation (Maxilact 40000) contaminated with proteinase, showed similar pH profiles of caseinolytic activity. Similar modes of casein hydrolysis (κ-, &gt; α s -, ≥ β-) were observed at pH 5·0 (the pH of Cheddar cheese), without detection of bitterness. The contaminated Maxilact preparation contained similar proteinase types to those detected in an autolysate of K. lactis . Both the autolysate and the Maxilact preparation contained acid endopeptidase (proteinase A), serine endopeptidase (proteinase B) and serine exopeptidase (carboxypeptidase Y) activities. Some aminopeptidase activity was also detected in both preparations. There were some differences in apparent molecular weight and charge properties between proteinase A and B and carboxypeptidase Y from the 2 proteinase sources.