Influence of temperature on microbial growth during processing of kochkäse cheese made from raw and pasteurised milk

Abstract

Kochkäse is a cheese traditionally produced from raw milk. The use of raw milk is preferred by consumers, but presents some safety concerns. This study investigated the microbial growth during the ripening stage of kochkäse, made from raw and pasteurised milk, at different temperatures (15, 25 and 35 °C). The growth of lactic acid bacteria, aerobic mesophilic bacteria and yeasts and moulds was analysed and predicted according to the Baranyi and Roberts model. Ripening at 15 °C maximised the ratio between the growth of desirable (lactic acid bacteria) and undesirable groups of microorganisms. Finally, the cooking step reduced the microbial count for both cheeses made, improving safety. The results represent an important step toward better understanding properties and safety aspects of kochkäse, and they indicate that the effect of the cooking process can be similar to that of pasteurisation, ensuring product safety when good manufacturing practices are adopted.