Multiple interactions between Streptococcus thermophilus, Lactobacillus helveticus and Lactobacillus delbrueckii strongly affect their growth kinetics during the making of hard cooked cheeses.

In hard cooked cheeses, any interactions between the thermophilic starters as they grow during the cheese-making are critical, since they modify bacterial growth kinetics and acidification kinetics, so affecting the ripening process and the final characteristics of the cheese. Twenty-four experimental hard cooked cheeses were made under controlled conditions, the milk being inoculated with various combinations of thermophilic strains of Streptococcus thermophilus, Lactobacillus helveticus and Lactobacillus delbrueckii. Over the first day of manufacturing we recorded a wide range of different growth kinetics for each starter species used, and a wide range of pH kinetics, depending on the starter combination.