The Mussel Myth

If you read any reference to cooking mussels post 1990 it will almost invariably tell you to not to eat mussels that have remained closed after cooking.

Prior to the 1970s revered cookery books such as ‘Larousse Gastronomique’ in 1965 and ‘Italian Food’ by Elizabeth David in 1966 made absolutely no mention of discarding unopened mussels.

The myth seems to have been started by the English food writer, Jane Grigson in her 1973 publication, Fish Book.

The exact quote is: ‘Throw away any mussels that refuse to open.’The reasoning was that these must have died prior to cooking and must therefore be rotten and unsafe to eat.

Jane Grigson is an excellent cook and writer, so unfortunately this advice was taken to be unimpeachable. By the 1970s, some 13 per cent of cookery books were agreeing; and by the 1980s, this had risen to 31 per cent. By the 1990s, there was almost universal agreement among the cookbook writers.

To keep them closed, the mussel has muscles. It uses its specific adductor muscles. When we cook them, the heat can have a few effects on the adductor muscles that keep the two halves of their shells stuck together.

Sometimes, the heat can denature the proteins in the adductor muscles so that they simply disintegrate, or sometimes, it can make one or both ends of the adductor muscles come unstuck from the shell.

During cooking a small percentage of mussels will actually open before they have been cooked long enough to kill any potential pathogens in them. If you removed them from the stove once they opened and ate these mussels, you would be at risk of food poisoning.

The best way to check the safety of mussels is to check them over before you cook them. Mussels have such a small mass that if they are invaded by a pathogen or germ, they will be overwhelmed almost immediately, and will smell bad. So just give them a sniff before cooking.

If we stop throwing out cooked mussels that stubbornly refuse to open, we can stop wasting each year some 370 tons of perfectly good seafood.