The Behavior of Yeast Populations in Stracchino Cheese Packaged under Various Conditions

The growth of yeasts, lactic acid bacteria, pseudomonads, and enterobacteria during the refrigerated storage of an Italian soft cheese (Stracchino) in various packaging conditions (under air, under vacuum, and in the presence of ethanol) was studied. Yeasts were found to play a significant role in cheese spoilage, producing unplesant flavors and odors and causing significant reductions in the shelf life of the paper-wrapped cheeses. Packaging under vacuum decreased the yeast growth rates 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 identified according to conventional methods. The most frequently isolated yeasts were Candida colliculosa , Debaryomyces hansenii , and Candida famata . Other species encountered were Tolurospora delbrueckii , Kluyveromyces marxianus , and Saccharomyces cerevisiae.