Influence of probiotic bacteria on the proteolysis profile of a semi-hard cheese

Two probiotic strains, Lactobacillus acidophilus and Lactobacillus paracasei subsp. paracasei, were used as adjunct cultures in semi-hard cheesemaking experiments, in order to study their influence on proteolysis during ripening. Cheeses with and without probiotic bacteria were manufactured. The population of probiotics remained above 107 cfu g−1 during all ripening, and they did not influence primary proteolysis. However, L. acidophilus produced a significant increase in the level of low molecular weight nitrogen compounds and individual free amino acids; the amino acid profiles were also different. Multivariate analysis of peptide profiles showed that samples were grouped mainly by ripening time, although the impact of probiotics was also noticeable. L. acidophilus showed a clear influence on secondary proteolysis, while a minor effect of L. paracasei was evidenced at the end of the ripening. These results showed that the tested strains influenced distinctly proteolysis of cheeses, probably as a consequence of their different proteolytic systems and their activity via the alimentary matrix (cheese).