Acid production, proteolysis, autolytic and inhibitory properties of lactic acid bacteria isolated from pasta filata cheeses: A multivariate screening study

Technologically relevant phenotypic properties of 78 strains of lactic acid bacteria isolated from pasta filata cheeses and from natural starter cultures were evaluated in order to select strains for the formulation of starters or adjuncts. A large diversity was found in inhibitory activity, acid production and proteolysis in milk, in autolysis, and in peptidase activities of cell-free extracts (CFEs). Multivariate statistical analysis was used to detect groups of isolates showing interesting patterns of properties. The largest diversity was found in lactococci. Twelve strains were selected for further study and the proteolytic activity of their CFEs was assayed in a sodium caseinate model system. Three individual CFEs and mixtures of CFEs from three- or four- strains produced peptide patterns (as measured by RP-HPLC of water-soluble nitrogen), which were clearly distinct from the control and from strains, which had either low general aminopeptidase activity or low PepX activity. Candidate strains to be used as starters or adjuncts in the manufacture of pasta filata cheese were identified.