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Characterization and Classification of Streptococcus Thermophilus and Lactobacillus Delbrueckii Subsp. Bulgaricus Strains Isolated from Traditional Greek Yogurts
Author(s) -
Xanthopoulos V.,
Petridis D.,
Tzanetakis N.
Publication year - 2001
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.2001.tb04632.x
Subject(s) - streptococcus thermophilus , acetoin , diacetyl , lactobacillus delbrueckii subsp. bulgaricus , lactobacillus , aroma , biology , food science , chemistry , microbiology and biotechnology , fermentation
Streptococcus thermophilus (74 strains) and Lactobacillus delbrueckii subsp. bulgaricus (75 strains) isolates from traditional Greek yogurts were tested on the basis of their acidification kinetics, acidity, viscosity, and aroma compounds formation in milk pure cultures. Strains of Lb. bulgaricus presented greater viscosity values, higher acidification activity and produced more acetaldehyde at culture pH 4.6 than S. thermophilus strains. Acetoin was formed only by the latter strains, while diacetyl was not detected in either species. Application of cluster and discriminant analysis permitted definition of distinct groups of strains and of the most significant variables to discriminate among them. Finally, classification and regression tree analysis allowed clusters characterization by critical values of the most discriminant variables. Evaluation of results as above could be a useful tool to select, through a large number of screened strains, the suitable starters for specific purposes.