Biocontrol of dairy moulds by antagonistic dairy yeast Debaryomyces hansenii in yoghurt and cheese at elevated temperatures

Some strains of the yeast Debaryomyces hansenii are known to be antagonistic toward moulds. In this study, we describe the inhibitory effects of a dairy strain of D. hansenii as a biocontrol agent against a number of dairy moulds in plain yoghurt and cheese under non-refrigerated conditions. This antagonistic yeast showed inhibition of growth of the following dairy moulds: Aspergillus sp., Byssochlamys fulva, Byssochlamys nivea, Cladosporium sp., Eurotium chevalieri, Penicillium candidum and Penicillium roqueforti. However, the inhibitory effect of this antagonistic yeast against dairy moulds is dependent upon the concentration of the moulds: the lower the concentration, the more effective the yeast. The findings of this study have implications for both cheese maturation and dairy biopreservation. Good manufacturing practice and hygiene to keep the contaminant load down is essential for the prevention of dairy spoilage.