DEVELOPMENT OF CHEESE FLAVOR FROM PEPTIDES AND AMINO-ACIDS BY CELL-FREE-EXTRACTS OF LACTOCOCCUS-LACTIS SUBSP CREMORIS B78 IN A MODEL SYSTEM

The formation of a cheese-like flavour from amino acids and peptides, by the action of enzymes from Lactococcus lactis subsp. cremoris B78, a Gouda cheese starter organism, was investigated. Cell-free extract ( CFE) was obtained from the organism after ultrasonic disruption of cel ls and subsequent removal of cell debris by centrifugation. The CFE wa s ultrafiltered to remove low-molecular-mass compounds (<500 Da). The retentate (CFE>500) was used as an enzyme source in incubation experim ents with various mixtures of amino acids in water and with peptide so lutions. These peptide solutions contained the alpha(sl)-casein peptid es alpha(sl)-CN(f1-23) and alpha(sl)-CN(f24-199) or a mixture of pepti des of molecular weight 500-5000 Da, isolated from Gouda cheese. The s olutions were incubated aseptically for one week at 25 degrees C. Sens ory analysis showed that a cheese-like flavour developed in amino acid mixtures containing free methionine or in mixtures of peptides contai ning methionine. In the latter case, methionine was released from the peptides by the action of proteolytic enzymes in the CFE>500. The form ation of volatile sulphur compounds from methionine could be demonstra ted by gas chromatography-mass spectrometry. The results indicated tha t non-proteolytic enzymes from mesophilic lactococci are important for flavour formation in cheese.