"In the worst case scenario, it could be the end of unpasteurised cheese," said Clare Cheney, secretary of The Specialist Cheesemakers Association.
But early indications of new unpublished research, reported by Dairy UK, could come to the rescue. The research shows that Mycobacterium bovis (M.bovis) a bacterium associated with tuberculosis (TB) in cattle is effectively killed off in unpasteurised Cheddar during the cheesemaking process.
Queen's University Belfast is investigating the survivability of M.bovis in unpasteurised Cheddar and Caerphilly hard cheeses, which undergo a long maturation process. The results for Caerphilly, while showing a reduction in M.bovis, are not as good as those for Cheddar. In separate, less advanced research, Campden BRI is investigating the survivability of Escherichia coli O157 (E.coli O157) in two other unpasteurised cheeses.
Once the results are known (probably around March 2011) the Food Standard Agency's (FSA's) Advisory Committee on the Microbiological Safety of Food (ACMSF) has agreed to review whether it needs to change its advice on the control measures for unpasteurised dairy products. Until then, the ACMSF said it sees "no public health concern".
While most cheese is made using pasteurised milk, a limited number of cheeses made from unpasteurised milk are available from supermarkets such as Sainsbury, Marks & Spencer and Waitrose, and specialist outlets and cheese merchants. But it is still a comparatively niche market.
The FSA advises vulnerable groups, such as the young, sick, elderly and pregnant women to avoid consuming unpasteurised dairy products. Pasteurisation of milk for 72°C for 15 seconds kills off M.bovis and other pathogens, such as salmonella and E.coli, provided it is properly carried out.
Unpasteurised milk products must come from herds that are regularly tested and shown to be free from TB. If herds lose their TB-free status, the local food authority will carry out a risk assessment on the public health implications for any products made prior to the loss of status and any measures necessary.
While tuberculosis in humans caused by M.bovis is low, the FSA Board wants reassurance that food chain controls are adequate.