Effect of pH on the extraction of protease from double layered cheese consisting of in Gouda and Cheddar cheese

Effects of pH in the buffer on the extraction ofprotease from Gouda side and Cheddar side in the double layered (composite) cheese ripened for 120 days were studied. When casein was extracted by the buffers whose levels of pH were 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5 and 7.0, their degradation patterns examined by polyacrylamid gel electrophoretic analysis were different from each other.Therefore, the results mean that the pH levels of buffer used for extraction affected the kinds of extractable proteases from composite cheese. Enzyme activities in the wide range of pH 3.0 to 7.0 were observed in the Gouda side and Cheddar side in comparison to each control cheeses. Effects of various enzyme inhibitors on decomposition of casein incubated pH at 6.0 and 7.5 extracted by the buffer of pH 6.0 were examined. Decomposition of casein was inhibited by pepstatin and ethylenediaminetetraacetic acid (EDTA) at pH 6.0 and by bestatin and soybean trypsin inhibitor (STI) at pH 7.5 in the Gouda side, and by EDTA at pH 6.0 in the Cheddar side. The resuls suggest that the Gouda side and Cheddar side of composite cheese have a numberof proteases extracted by the pH 6.0 of buffer.