Thermal Inactivation of Hepatitis A Virus, Noroviruses, and Simian Rotavirus in Cows' Milk.

Consumption of raw or unpasteurized milk is a risk for the consumers because indirect contaminations such as fecal-cross-contamination could occur and determine the presence of enteric viruses. In this study, milk was treated with several temperature and time combinations chosen by performing a preliminary experiment to evaluate the intervals needed to inactivate Hepatitis A virus (HAV) HM175 strain, noroviruses genogroups I and II (GI and GII), and simian rotavirus SA11 at different temperatures. Results were obtained by measuring the genome copies and infectious units by real-time PCR and plaque assays respectively. At 85 °C, one minute and two minutes were needed to achieve 6.6 log10 ± 0.2 and 8 log10 ± 0 reductions of genome copies of HAV respectively. Similar genome copies reduction was also observed for noroviruses (GI and GII) and simian rotavirus. At higher temperatures, 90 s (s) at 90 °C and 60 s at 95 °C were needed to achieve 8 log10 ± 0 reductions of the genome copies of all studied viruses. Significant higher sensitivity of the infectious units of both HAV and simian rotavirus to heat treatment of milk than their genome copies was observed. At boiling point of milk (100.5 °C), 40 s were needed to achieve 8 log10 ± 0 reductions of genome copies of all the studied viruses, while 10 s were needed to achieve 6 log10 ± 0 reductions of the infectious units of HAV and simian rotavirus. Significant higher reduction of infectious units than genome copies was observed confirming that genome copies reduction does not correspond to infectious virus.

Safety of frozen liver for human consumption.

The objective of this study was to ensure and evaluate the safety of imported frozen beef liver traded in supermarkets of Kafr El-Sheikh Governorate, Egypt, through detection of Salmonella typhimurium, Salmonella enteritidies, Escherichia coli O157:H7, antibiotic residues, and aflatoxin B1 residue. Fifty samples of imported frozen liver were randomly collected from different shops at Kafr El-Sheikh Governorate for isolation of S. typhimurium, S. enteritidies, and E. coli O157:H7. The results revealed that for both microorganisms 4% of the examined samples presumed to contain Salmonella and E. coli O157:H7 organisms, according to the colonial character on Harlequin Salmonella ABC agar media and Harlequin SMAC-BCIG agar media. According to biochemical and serological identifications, both organisms could not be detected in the examined samples. A total of 29 (58%) samples were positive for antibiotic residues, using the Premi test (a broad-spectrum screening test for the detection of antibiotic residues in meat) at or below the maximum residue limits. In addition, aflatoxin B1 was detected in one (2%) samples with a concentration of 1.1 µg/kg. The results reflect that there was good hygiene practice for handling and preparation of frozen liver while selling to consumers. However, a high percentage of antibiotic residues reflect ignorance of withdrawal time before slaughtering of animals as well as misuse of antibiotics in veterinary fields. Furthermore, aflatoxin B1 residue was detected in examined frozen liver samples at a concentration below the maximum residual level, which is not enough to cause threat to humans, but it is enough to cause problem if it is eaten regularly reflect contamination of animal feed with aflatoxins.