Comparative study by multivariate statistical analysis of proteolysis in asodium caseinate solution under cheese-like conditions caused by strains of Lactocaccus

Sonicatcd cells of Lactcoccus lactis subsp. cremoris 223, 227, SK11, AM1, W g2 or L. lactis subsp. lactis UC317 were added to a sodium caseinate soluti on under conditions found in Cheddar or Gouda cheese during ripening (pH 5. 25 and 5.0% (w/v) NaCl). Proteolysis was assessed by urea-polyacrylamide Ee l electrophoresis of the pH 4.6- and ethanol (70%)-insoluble fractions and reverse-phase-high-performance liquid chromatography of the ethanol (70%)-s oluble fraction, and the resulting peptide profiles were analysed by princi pal component analysis and hierarchical cluster analysis. Statistical analy sis of peptide profiles of the ethanol (70%)-soluble fraction from 2, 9, 17 or 23 d-old samples grouped the strains into three clusters which were sim ilar to those found earlier for the same strains in an experiment with mini ature Cheddar-type model cheeses by Shakeel-Ur-Rehman, Pripp, McSweeney and Fox (1999, Luit, 79, 361-38.3). (C) 2000 Elsevier Science Ltd. All rights reserved.