Residual Casein Fractions in Ripened Cheese Determined by Polyacrylamide-Gel Electrophoresis

Abstract

Polyacrylamide-gel electrophoresis (PAE) of ripened-cheese caseins provides an ideal means of studying cheese-ripening by detecting small changes in the specific casein fractions. Properties, such as molecular sieving, and the facility to use simultaneously casein standards, apparently are important advantages of PAE.Rennet enzymes appear specifically to alter αs1-casein after curd formation in Cheddar cheese manufacture. β-Casein evidently is unaltered by the rennet enzymes. The caseins were hydrolyzed to different extents in the cheese varieties examined. The αs1-fraction is degraded in every cheese; however, β-casein appears largely intact in some varieties, whereas its content is appreciably diminished in others. This reflects important differences in the proteolytic abilities of microorganisms peculiar to a given variety of cheese. An elucidation of these microbial enzymes should lead to a better understanding of the ripening process.