Flavour forming abilities and amino acid requirements of Lactococcus lactis strains isolated from artisanal and non-dairy origin

Wild lactococci from raw and fermented milk and from non-dairy origin were individually used in milk and in a cheese model to screen for their flavour forming abilities. Organoleptic evaluation revealed that wild strains gene rally produce specific flavours distinct from those produced by industrial strains. Analysis of volatiles by gas chromatography mass spectrometry (GC- MS) showed that several wild strains produced relatively high levels of pri mary alcohols and branched aldehydes in these model systems, most likely or iginating from amino acid degradation. A good correlation between GC-MS dat a and organoleptic descriptions was perceived. Using the single omission te chnique, it was shown that wild strains required between 1 and 4 amino acid s for growth, whereas the industrial strains generally needed 9-10 amino ac ids for growth. This indicates that wild strains are more dependent on thei r own synthesis of amino acids. Concomitantly, these strains probably posse ss more active amino acid convertases, which could explain their ability to produce unusual flavours. (C) 2000 Elsevier Science Ltd. All rights reserv ed.