بررسي تغييرات ميكروبي پنير پوستي طي دوره رسيدن

Microbiological Changes of Pousti Cheese During Ripening

Introduction: Pousti cheese, a prominent cheese made in the eastern part of Iran from the whole raw eweʹs milk without any starter cultures. The cheese has a distinctive organoleptic characteristic and properties making this product popular. The concern about this product is its susceptibility to contamination by pathogens due to the fact that this product is locally ripened and aged in goatʹs skin for at least a month and consumed regardless of its microbial safety. The aim of this study is to understand the microbiological changes in this cheese during ripening. Materials and Methods: Three batches of cheese were prepared following the traditional method using whole raw eweʹs milk. Calcium chloride and starters were not added to the milk. In this study microbial characteristics of unripened cheese and its changes during 90 days of ripening were investigated. The enumeration of total mesophilic bacteria, total coliforms, Lactic acid bacteria, Staphylococcus aureus as well as yeasts and molds were performed. Results: Total mesophilic bacterial count decreased and on 60th day of ripening no mesophilic bacterium was isolated. On the 30th day of ripening coliforms and Staphylococcus aureus were isolated from samples which were totally inhibited by the 60th day. Yeasts and molds were isolated and there was a slight increase in their number during ripening. A slight increase of NALAB, was observed during the first 30 days, however the number was gradually decreased during the rest of ripening period. Conclusion: The results of this investigation suggested that the product does not meet national standard of ripened cheese.