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Changes in the microflora of manouri, a traditional Greek whey cheese, during storage
Author(s) -
Lioliou K,
LitopoulouTzanetaki E,
Tzanetakis N,
Robinson R K
Publication year - 2001
Publication title -
international journal of dairy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.061
H-Index - 53
eISSN - 1471-0307
pISSN - 1364-727X
DOI - 10.1046/j.1364-727x.2001.00017.x
Subject(s) - debaryomyces hansenii , food science , biology , enterobacteriaceae , bacteria , yeast , water activity , chemistry , microbiology and biotechnology , water content , biochemistry , escherichia coli , genetics , gene , geotechnical engineering , engineering
Six batches of manouri cheese were manufactured, and selected microbial groups were counted throughout storage for 20 days at 4°C. The counts of all the microbial groups increased ( P < 0.05) throughout storage and reached higher levels in cheeses made in summer than in those made in spring. Moreover, the micro‐organisms developed better on the cheese surfaces than in the interiors, especially in summer. The pH (6.78–7.33) and salt‐in‐moisture content (2.53–3.72) of the cheeses did not seem to affect the growth of the bacteria and yeasts present. The isolates of enterobacteriaceae were mainly Hafnia (68.75%), while the isolates from the Baird–Parker medium were mainly staphylococci. There was a great diversity of yeast species, but Debaryomyces hansenii and Pichia membranefasciens predominated. The isolates of enterobacteriaceae, staphylococci and—to a lesser extent—yeasts were proteolytic, but the free amino acid (N‐NH2) content of the cheese did not increase significantly during storage (136.4–225.2 mg/kg glycine equivalent). It also seemed that milk fat was not degraded to any great extent (acid degree value 0.09–0.19) by the lipolytic activity of the strains. The main enzymes detected in selected isolates of enterobacteriaceae were leucine aminopeptidase and phosphohydrolase.