Characterization of Cheddar cheese juice is a useful index of starter strain related proteolysis during ripening

Cheese juice is the aqueous phase of cheese expressed by hydraulic pressure and contains a range of proteolytic enzymes and the end products of proteolytic activity. During ripening of cheeses made with three different strains the levels of total N, peptide profiles and released free amino acids were monitored periodically in cheese juice. Differences in the levels of nitrogen, peptides and free amino acids in the aqueous phase of cheese throughout ripening were observed. These differences may reflect differences in cell envelope proteinase (CEP) specificity of each of the lactococcal starters (i.e. CEP I or CEP III) and the levels of intracellular peptidases released on autolysis and permeabilization. Differences in proteolytic indices found in juice over ripening appeared to be starter strain related. Overall, the usefulness of cheese juice as an index of proteolysis during ripening of Cheddar cheese was demonstrated.