Effect of rennet on the composition, proteolysis and microstructure of reduced-fat Cheddar cheese during ripening

摘要

Rennet is an important ingredient in Cheddar cheese manufacturing and both the type used and the concentration applied can affect the ripening process. In this work, reduced-fat Cheddar cheese was produced using different concentrations of microbial rennet (Hannilase; 0.026, 0.052 and 0.150 international milk clotting units (IMCU).g(-1) of milk) as well as recombinant camel chymosin (0.052 IMCU.g(-1) of milk). The composition of the resulting cheeses was not statistically different, but the ratio of pH 4.6 soluble nitrogen/total nitrogen (pH 4.6-SN/TN) increased significantly with increasing Hannilase rennet concentration. This ratio was also significantly lower in the cheese made with recombinant camel chymosin at a similar rennet concentration. Microstructural, biochemical and textural changes in the cheese were also monitored during ripening. The gel made with a high rennet concentration was qualitatively more porous but these changes in porosity were not reflected in the freshly pressed cheese. After 31 weeks of ripening, the cheese made with recombinant camel chymosin had a thicker protein network compared to the cheese made with microbial rennet (Hannilase), possibly due to lower proteolysis. Most of the Hannilase rennet was lost to the whey when the rennet was increased above the concentration of 0.052 IMCU.g(-1) of milk. A lower concentration of Hannilase rennet may prove beneficial, as the texture was not significantly affected at the end of the observed ripening period. Recombinant camel chymosin may potentially be used as a substitute for products requiring lower proteolysis during ripening. However, the texture of this cheese was harder than the cheese made with Hannilase rennet at the end of the ripening period.