A recent study by Cornell University, funded by the US Food and Drug Administration (FDA), has found that aging raw milk cheese for 60 days or longer is not enough to eliminate the Highly Pathogenic Avian Influenza H5N1 virus. However, the study suggests that heating raw milk to adequate parameters or manufacturing cheese at a pH level of 5.0 or lower can effectively inactivate the virus.
The FDA requires unpasteurized milk to undergo a curing process for a minimum of 60 days to kill bacterial pathogens. But research has not yet determined whether this process also eliminates HPAI H5N1. Given the ongoing outbreak in North American dairy cattle, the study aimed to fill this knowledge gap.
Researchers evaluated the stability of HPAI H5N1 in raw milk cheese during production and aging under varying pH conditions. They found that lower viral RNA loads were detected in samples from the pH 5.0 group compared to other groups. The virus was also not detected in whey and curd samples collected from the pH 5.0 group.
The study validated its findings by assessing the stability of HPAI H5N1 during cheese aging or curing at 4°C over a 60-day period. The results showed that infectious virus persisted throughout the cheesemaking process and for up to 60 days of aging in some groups, but was not detected in others.
The researchers conclude that their findings highlight potential public health risks of consuming raw milk cheese and emphasize the need for additional mitigation steps in cheese production to prevent human exposure to the infectious virus.
Source: https://www.food-safety.com/articles/10229-fda-backed-study-shows-aging-raw-milk-cheese-does-not-inactivate-avian-flu-but-low-ph-helps