The occurrence and growth of yeasts in Camembert and Blue-veined cheeses

Yeast populations greater than 106 cfug were found in approximately 54% and 36%, respectively in surface samples of retail Camembert (85 samples) and Blue-veined (45 samples) cheeses. The most predominant species isolated were Debaryomyces hansenii, Candida catenulata, C. lipolytica, C. kefyr, C. intermedia, Saccharomyces cerevisiae, Cryptococcus albidus and Kluyveromyces marxianus. The salt concentration of the surface samples of the cheeses varied between 2.5–5.5% (ww) (Camembert) and 7.5–8.3 (Blue-veined), depending upon brand, and influenced the yeast ecology, especially the presence of S. cerevisiae. Yeasts grew to populations of 106–108 cfug when cheeses were stored at either 25 °C or 10 °C. These populations decreased on continued storage at 25 °C, but such decreases were not so evident on storage at 10 °C. The properties of yeasts influencing their occurrence and growth in cheeses were: fermentation/assimilation of lactose; production of extracellular lipolytic and proteolytic enzymes, utilisation of lactic and citric acids; and growth at 10 °C.