How safe are UK oysters?
The old adage that it's only safe to eat oysters when there's and 'r' in the month no longer rings true – as some would say it's never safe to eat UK oysters! In the three months between December 2009 and February 2010, 32 restaurants and hotels were hit with oyster related outbreaks and 230 people were affected.The scandal of contaminated oysters follows hot on the heels of an outbreak of norovirus (which causes projectile vomiting and diarrhoea) at Heston Blumenthal’s Fat Duck restaurant last year. Chefs at Raymond Blanc’s Le Manoir aux Quat’ Saisons, were so concerned that they took oysters off the menu for almost a year.Britain’s oyster industry is worth about £30m a year and producers’ livelihoods are being jeopardised by food poisoning incidents linked to oysters. They point out that norovirus, which contaminates the oysters, originates in humans and so the source must be sewage being discharged into rivers and the sea.Norovirus is killed at high temperatures but oysters are typically eaten raw. In February last year Blumenthal was forced temporarily to close the Fat Duck, after 529 diners fell ill. The Health Protection Agency found sewage in oysters was most likely to blame. “Oysters harvested from sewage-contaminated waters will feed on the faecal residues,” it said.Water companies are allowed to dump raw sewage into rivers and the sea during wet weather to stop it backing up into homes, but oyster producers want to see more investment to limit the amount that is discharged. The Colchester Oyster Fishery, which supplied the Fat Duck, now conducts rigorous tests for norovirus on oysters from the River Colne in Essex. If you’re serving oysters:
- – Make sure your supplier proves they’re from Category A or B shellfish beds (as these are the ones allowed for human consumption). However, although Cat A oysters are from the cleanest waters they are not required to undergo depuration (a period in clean water tanks to filter out germs). So Cat B oysters may in fact be safer!
- – If you want to serve Cat A oysters raw, make sure your supplier can prove that they have undergone depuration and that regular norovirus tests are being carried out
- – Ideally cook to 75°C. Before cooking, make sure the oysters are alive. Tap any open shells to make sure they close before cooking and do not use any that don't open after cooking