Multivariate statistical analysis of peptide profiles and free amino acidsto evaluate effects of single-strain starters on proteolysis in miniature Cheddar-type cheeses

Multivariate statistical analysis of reverse phase-high-performance liquid chromatography (RP-HPLC) chromatograms of ethanol (70%)-soluble and -insolu ble fractions and free amino acids from miniature Cheddar-type model cheese s was performed to evaluate effects of different single-strain starters on proteolysis. The statistical analysis was done by using principal component analysis (PCA) and hierarchical cluster analysis (HCA). Based on results f rom the statistical analysis, we were able to group strains according to th eir effects on chromatographic profiles and free amino acids. PCA, using va riables standardised to zero mean, and the covariance matrix made it possib le to identify peaks which were strongly influenced by the different starte rs. Multivariate statistical analysis of chromatographic profiles was a mor e objective and powerful approach for evaluating proteolysis in cheese, tha n visual assessment of the chromatograms. (C) 1999 Elsevier Science Ltd. Al l rights reserved.