84. The Influence of Lactic Streptococci on the Ripening of Cheddar Cheese

Abstract

1. The process of ripening in experimental cheeses was followed by periodic estimations of the amounts of various types of protein degradation product formed.2. No connection between the type of nitrogen partition and the commercial quality of the ripened cheese could be traced.3. The proteolytic powers of the various pure cultures of streptococci used as starters in the cheese vats seemed to have little influence on the rate of proteolysis in the cheeses during the ripening period. The main trend of the protein breakdown was governed by the rate and total extent of acid formation in the milk and curd during the manufacturing process. This suggests that the rennet enzyme is the principal proteolytic agent, and that the most significant function of the streptococci is the formation of acid which in turn influences the rate of action of the rennet enzyme.4. No specific connection between the numbers of streptococci present in the cheese milk at the time of renneting and the rate of ripening of the cheese could be traced.5. Some evidence was found tending to suggest that minor differences in the type of protein degradation occurring during the ripening period influenced the changes of bacterial flora in the cheese. Lactobacilli appeared to develop earlier where the proportion of simpler protein derivatives was high.