Biochemical Changes During Ripening of Cheddar Cheese Prepared by Milk Clotting Enzyme from Rhizopus oryzae

The Cheddar cheese prepared from fresh cow milk by using crude and purified enzyme from Rhizopus oryzae and the commercial Meito enzyme was examined for biochemical changes during accelerated ripening at 14°C for 42 days. No difference in initial moisture content and pH was observed in any of these samples. However, 4.0% loss in moisture has been observed in cheese samples from crude and purified Rhizopus enzyme, while the value for cheese prepared from Meito enzyme was 3.75%. Similarly, pH increased faintly in cheese samples prepared from crude, purified Rhizopus and Meito enzymes by 4.1, 3.5 and 3.1 %, respectively. Higher value of 1.36% for titratable acidity was reported for cheese prepared from Meito enzyme followed by 1.35 and 1.25% for purified and crude enzyme preparations from Rhizopus oryzae. The soluble nitrogen fraction in cheese samples increased by 120, 116 and 120% for crude, purified Rhizopus and Meito enzyme preparations, respectively. The maturity index of 14.13 was observed for Meito enzyme prepared cheese compared to 14.09 and 13.67 for crude and purified Rhizopus enzymes, respectively. Electrophoretic studies revealed increase in number of bands from 0-28 days of maturation, depicting increased proteolysis of casein. The degradation of (beta)casein was comparatively lesser than (alpha)-casein in all the samples prepared here. Butyric acid was the main free fatty acid present in all the cheese samples and its concentration was higher in cheese samples prepared from both purified Rhizopus (88 (mu)g /g) as well as Meito enzyme (87 (mu)g/g) than the samples prepared by using crude enzyme (56 (mu)g/g). The results indicated that the milk clotting enzyme from Rhizopus oryzae can be used as rennet substitute.