This study was conducted to investigate the microbiological quality of milk and thermal and aging processes for the inactivation of viruses in food. For the first part of this study, raw cow’smilk samples were collected from a collection center in the city of Mashhad, Iran. A total of 19 raw cow's milk samples were collected and simultaneously analyzed for male-specific (F+) MS2 coliphage and E. coli using culture-based methods and for enteric viruses by reverse transcriptase semi-nested PCR using primer sets specific for human norovirus Group I (HNV-GI), human norovirus Group II (HNV-GII) and enteroviruses (EV). Seven out of 19 (36.8%) raw milk samples tested positive for human noroviruses (HNV). The genotypes detected were HNV-GI and HNV-GII. Three positive samples contained both genotypes and 2 samples were positive for either of HNV-GI and HNV-GII. No sample tested positive for EV. The correlation between the occurrence of HNV and the microbial indicators was studied. The statistical analysis using first and second order regression revealed that there is no correlation between MS2 and E. coli. Similarly, no correlation was noticed between the occurrence of MS2 and HNV. However, frequency distribution analysis indicated that 3 out of 4 (75%) of raw milk samples containing MS2 at a concentration higher than 104 pfu/100ml were also positive for noroviruses. The limited data on the occurrence of noroviruses in raw milk suggest a poor sanitation and hygiene practices at the facility and indicates a possible correlation between the viral indicator at high concentration and human noroviruses; however, this analysis needs further investigation in a larger scale study.

Keywords