Survival of enteric viruses during yoghurt making process using male-specific coliphage

Abstract

The effects of yoghurt-making process on the survival of male specific coliphage (MS2) in raw milk with different fat content, as well as the survival of MS2 during the storage of yoghurt were evaluated. All samples were analyzed for pH, acidity, and virus count. The results showed that the heat treatment of milk (85 °C, 30 min) decreased the recovery of coliphage MS2 from approximately 7 to 0.97 and 1.49 log10 (pfu/ml) in the milk samples with 2.5% and 3% fat, respectively. No MS2 could be detected in the heat-treated milk sample with 1.5% fat. The recovery of MS2 during incubation was decreased as the acidity increased particularly in milk with 1.5% fat. Moreover, during the storage time (10 days), yoghurt samples with 1.5% and 3% fat had the lowest and the highest recovery for coliphage MS2, respectively. Practical applications Enteric viruses have been reported in dairy products such as pasteurized milk, cheese, and yoghurt. Bacteriophages are viruses that infect bacteria, and exist in ecosystems in which bacteria have been located. A case in point is the vats that are used for the fermentation of yoghurt and other dairy products. This phenomenon renders bacteriophages suitable as surrogates for the evaluation of the survival of enteric viruses in foodstuffs, as is outlined in the present work and similar studies. Due to the health concerns caused by enteric viruses, as well as an increase in the consumption of dairy products, a considerable need for further investigation of their survival is recognized. In order to achieve this aim, researchers can take advantage of the procedure applied here, which has proven reliable and practical for the aforementioned purpose.