Yeast populations in Sardinian feta cheese

In this study, the yeast populations in feta cheese from two different Sardinian dairies were examined. Samples of good quality feta (32) and samples of feta with a slimy surface defect (10) were examined from Dairy A. Similar, samples of good quality feta (23), feta with slimy surface defects (14) and samples with swelling defects (6) were examined from Dairy B. Kluyveromyces lactis was the dominating species in feta from Dairy A (95.2% of samples) followed by Debaryomyces hansenii (76.2%), Dekkera anomala (28.6%) and Dek. bruxellensis (19%). D. hansenii was dominant in samples from Dairy B (93%), followed by K. lactis (23.3%), Geotrichum candidum (23.3%) and Dek. anomala (18.6%). No significant difference was observed between the occurrence of yeast species in feta of good quality and in feta with slimy surface defects, thus confirming that slimy production is not associated with yeast contaminations. The swelling of samples observed in Dairy B seems to be caused by Dek. anomala. In fact, this strong fermenting species was present in all swelled samples in numbers exceeding 10(6) CFU g(-1), while it was isolated in very low concentration in only 5.4% of good samples.