Biochemical characteristics of strains of lactic acid microorganisms used in cheese making
Matveeva, E.K.; Krasheninin, P.F.
Prikladnaia Biokhimiia i Mikrobiologiia 9(1): 49-54
1973
ISSN/ISBN: 0555-1099 PMID: 4633826 Document Number: 58964
5 strains of Lactobacillus acidophilus, 9 of L. bulgaricus, 11 of L. helveticus, 15 of Streptococcus thermophilus and 5 of Str. lactis were studied after 7 days' cultivation in skim-milk) with a view to their use as cheese starters. Significant differences within species were found in proteolytic activity (especially the streptococci), energy of acid formation, milk coagulation time, chemostability (determined as milk coagulation time after 10 min at 60 deg C), and production of aromatic substances (acetoin + diacetyl). Most of the 20 nitrogen fractions (isolated by gel filtration) from the Lactobacillus cultures contained considerably more N than those from the streptococcal cultures. Fractions from strains within the same species were similar in molecular spectrum, although some differences in proteolytic enzymes were found. L. helveticus strain Ag had the highest free amino acid content (9.68 mg %) and Str. thermophilus strain K the lowest (0.45 mg %).