Contribution of starter lactococci and non-starter lactobacilli to proteolysis in Cheddar cheese with a controlled microflora

Cheddar cheeses were manufactured under controlled microbiological conditions to study the relative contribution of starter and non-starter bacteria to cheese ripening. In each of two trials, four cheeses were manufactured with or without a starter culture (starter-free cheeses were chemically acidified using glucono-δ-lactone). Adjunct cultures of mesophilic lactobacilli were added to one chemically-acidified and one starter cheese. Assessment of proteolysis showed a major contribution by the starter in comparison to the non-starter bacteria to the formation of free amino acids and, to a lesser extent, water-soluble nitrogen. Reversed phase-HPLC of ethanol-soluble and -insoluble fractions of the water-soluble extracts detected some peptides (produced by lactobacilli) which were present in profiles of the starter-free cheese containing the adjunct but were not present in its corresponding control.