THE BEHAVIOR OF YEAST POPULATIONS IN STRACCHINO CHEESE PACKAGED UNDERVARIOUS CONDITIONS

The growth of yeasts, lactic acid bacteria, pseudomonads, and enteroba cteria during the refrigerated storage of an Italian soft cheese (Stra cchino) in various packaging conditions (under air, under vacuum, and in the presence of ethanol) was studied. Yeasts were found to play a s ignificant role in cheese spoilage, producing unplesant flavors and od ors and causing significant reductions in the shelf life of the paper- wrapped cheeses. Packaging under vacuum decreased the yeast growth rat es and reduced the populations attained at the end of the exponential phase of growth, resulting in a shelf-life extension of the Stracchino cheese of over 28 days. A total of 129 yeasts isolates were identifie d according to conventional methods. The most frequently isolated yeas ts were Candida colliculosa, Debaryomyces hansenii, and Candida famata . Other species encountered were Tolurospora delbrueckii, Kluyveromyce s marxianus, and Saccharomyces cerevisiae.