COMPARATIVE STUDY ON PHYSICO-CHEMICAL AND MICROBIOLOGICAL PROPERTIES OF SOFT CHEESE PREPARED BY USING CRUDE AANK (Calotropis gigantea) AND JACKFRUIT (Artocarpus heterophyllus) PROTEASES

Abstract

The main objective of this dissertation work was to perform comparative study on the physico chemical and microbiological properties of soft cheese prepared by using crude aank (Calotropis gigantea) and jackfruit (Artocarpus heterophyllus) proteases. Milk clotting activity (MCA), proteolytic activity (PA) and protein content of the extracted proteases were measured. Optimum conditions of temperature and pH of milk for maximum MCA and minimum time of coagulation (TOC) were determined by response surface methodology. The crude plant proteases were used as milk coagulants in soft cheese preparation at optimized conditions. The physicochemical and microbiological properties of prepared cheeses were compared with rennet cheese. Numerical optimization study revealed that the optimum condition for milk clotting was found to be 45°C and pH 6.5 for crude aank protease, as well as 65°C and pH 6.5 for crude jackfruit protease. The optimized TOC and MCA for crude aank protease were found to be 40 s and 300 units respectively, while; TOC and MCA for crude jackfruit protease were found to be 108 s and 111.11 units respectively. The physico-chemical analysis showed non-significant (P>0.05) differences in protein content among all samples. Significantly (P<0.05) higher level of moisture and ash content, and lower level of fat and calcium content were observed in cheese prepared by crude aank and jackfruit proteases when compared to rennet cheese. Acidity of cheese made using crude jackfruit protease was significantly different (P<0.05) with rennet cheese, while no significant difference (P<0.05) in acidity was observed between cheeses made using jackfruit protease and rennet. Microbiological analysis revealed significantly (P<0.05) higher level of total plate count in cheese made using crude aank protease while significantly (P<0.05) lower level of TPC was seen in cheese made using jackfruit protease when compared to rennet cheese. There was no significant difference (P>0.05) in yeast and mold count among all the cheese samples