Changes in the microflora of manouri, a traditional Greek whey cheese, during storage

Six batches of manouri cheese were manufactured, and selected microbial gro ups were counted throughout storage for 20 days at 4 degreesC The counts of all the microbial groups increased (P < 0.05) throughout storage and reach ed higher levels in cheeses made in summer than in those made in spring. Mo reover, the micro-organisms developed better on the cheese surfaces titan i n the interiors, especially in summer. The pH (6.78-7.33) and salt-in-moist ure content (2.53-3.72) of the cheeses did trot scent 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 w ere mainly staphylococci. There was a great diversity of yeast species, but Debaryomyces hansenii curd Pichia membranefasciens predominated. The isola tes 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 equivalen t). 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 a minopeptidase and phosphohydrolase.