Thermal inactivation of MS2 bacteriophage as a surrogate of enteric viruses in cow milk

Abstract

This study examined the effect of 4 thermal processing methods on inactivation of male-specific bacteriophage MS2 in cow milk. MS2 was used as a viral surrogate of enteric viruses in this inactivation study. Milk samples were spiked at 10, 103, 105, and 107 PFU/ml with a milk fat content of 1.5, 2.5 and 3% weight per volume. We found that with higher milk fat content, survival of MS2 increased in the samples spiked with 105 or 107 PFU/ml, indicating that increasing the milk fat content had a significant effect on the survival of MS2 (p < 0.05) in the thermally processed samples. The inactivation results suggest that the most effective thermal processing for viral inactivation in cow milk was having a high temperature long time (HTLT: 85 °C for 30 min) followed by boiling for 2 min. The least effective thermal processing was low temperature for a long time. Therefore, inactivation of enteric viruses in dairy products with a high level of contamination can be effectively achieved under severe thermal processing such as HTLT, or boiling.