Hydrophilic and hydrophobic peptides produced in cheese by wild Lactococcus lactis strains

AIMS: To study the production of hydrophilic and hydrophobic peptides in cheese by 32 wild Lactococcus lactis strains of different RAPD patterns and to compare them with the peptides produced by lactococcal cells incubated with whole casein. METHOD AND RESULTS: Chromatograms of peptides from cheeses made using each strain as single starter culture were divided into five regions, and strains were classified in three groups by hierarchical cluster analysis of region areas. Thirty out of the 32 wild L. lactis strains produced higher levels of hydrophobic peptides in cheese than on whole casein. CONCLUSIONS: Cheese was a more favourable substrate than whole casein for hydrophobic peptide formation by L. lactis strains. SIGNIFICANCE AND IMPACT OF THE STUDY: New strains of lactococci should be screened for bitterness under cheese conditions, as the formation of hydrophobic peptides may be underestimated in assays with casein as substrate.