Yeasts associated with Cheddar and Gouda making.

Sources of yeast contamination which may lead to contamination of the curd during Cheddar and Gouda cheese making, were examined in a single cheese factory. A total of 187 representative yeast isolates present in the factory environment, on working surfaces, the brine and on workers' hands and aprons were identified according to conventional methods and cellular long-chain fatty acid analyses. Product line samples were taken at critical control points in the manufacturing process and analysed after incubation at 25 degrees C for 96 h. The most prevalent isolates belonged to the genera Debaryomyces and Candida. Other genera encountered were Cryptococcus, Rhodotorula, Yarrowia, Pichia, Trichosporon, Torulaspora, Issatchenkia, Saccharomyces and Zygosaccharomyces. Characterization of the predominant yeast isolates indicated that the cheese brine was responsible for the largest variety and number of yeast isolates yielding a total of 64 yeast strains belonging to nine different genera.