Food Microbiology

One of the most important problems of Kashar cheese producers is the mold growth on the surface during storage. Williopsis saturnus var. saturnus killer yeast has been reported to have antagonistic effect on mold and yeast reproduction in many studies. In this project, to investigate antifungal effect of W. saturnus var. saturnus yeast, it was applied directly on the cheese or with cheese whey protein based edible coatings to prevent mold growth. The reason for the use of yeast cultivar with edible coating is to produce edible films that contain antifungal effects by encapsulating yeast. In our study, 50 g of cheese samples were coated with edible films based on whey protein with or without W. saturnus var. saturnus or yeast without coating at a concentration of 6.9 log cfu/g and dried for 1 hour. They were packed in vacuum and without vacuum packages, stored at 4°C for 56 days. The number of W. saturnus var. saturnus, total bacteria, lactic acid bacteria, molds and yeast counts were observed throughout the storage period. Water activity, color and pH of Kashar cheese samples were also observed. The results showed that in the 56 days of the storage period; total bacteria and lactic acid bacteria populations were not affected by coating application with yeast; however, the number W. saturnus var. saturnus yeast was increased by 1 log cfu/g. Application of W. saturnus var. saturnus was observed to slight decrease the growth of other yeasts and molds on the cheese samples. The color of all cheese samples did not change with coating and yeast application. The pH and water activity of the cheeses showed an increase. In a conclusion, application of whey protein coating containing W. saturnus var. saturnus on the cheese samples have a potential to inhibit mold growth during shelf life.