Survival of Salmonella Typhimurium During the Ripening of Herby Cheese (Otlu Peynir)

Abstract

This study was conducted to determine the survival of Salmonella Typhimurium during the ripening period of herby cheese made traditionally from raw milk. For this purpose, the cheese milk was inoculated with S. Typhimurium at the level of 103 and 105 colony-forming units/mL, and then both manufactured herby cheeses were divided into two groups equally. The herby cheeses were stored by using two different methods for ripening, either embedding into the soil or putting into brine, and analyzed on the 1st, 7th, 15th, 30th, 60th and 90th days of ripening period. At the end of the storage period, S.Typhimurium could not be detected in embedded herby cheese at both levels of the inoculation; whereas it was found that the number of the bacterium was just decreased to 2.60 and 3.15 log MPN/g in brined herby cheese for each inoculation levels, respectively. The results indicated that S. Typhimurium could survive at least 60 days in embedded herby cheese and till the last days of the ripening in brined herby cheese. This point should be taken into account for the potential risk to public health. PRACTICAL APPLICATIONS Milk and other dairy products may be contaminated with some pathogenic bacteria such as Salmonella spp. Salmonella Typhimurium is an emerging food pathogen in cheeses when it contaminates the milk. In this study, the behavior of S. Typhimurium was investigated during ripening of herby cheeses. Herby cheese made traditionally from raw milk were stored either embedding into the soil or putting into brine. As a result, it was found that embedded cheeses were safer than brined cheeses with respect to the S. Typhimurium contamination at the end of the ripening period.