Role of Proteolytic Enzymes of Streptococcus lactis, Penicillium roqueforti, and Penicillium caseicolum during Cheese Ripening

With the aim of determining the exact action of various enzymes from dairy microorganisms, proteolytic preparations were added to aseptic model curds free of microorganisms. Casein breakdown was followed by precipitation techniques, gel filtration, and acrylamide agarose gel electrophoresis. Purified acid protease from P. roqueforti and neutral protease from P. caseicolum induced large increases in pH 4.6-soluble nitrogen and nonprotein nitrogen but had little effect on production of free amino-acids. Crude homogenates of S. lactis led to little increase in pH 4.6-soluble nitrogen and nonprotein nitrogen but to a high increase of free amino-acids. The acid protease from P. roqueforti and the neutral protease from P. caseicolum play a fundamental role in the proteolysis induced by their microorganisms during cheese ripening.