This might seem a silly question. I've just been watching 'Hairy Bikers' on TV and they have showed us how to live clean cockles of grit by putting them in a bowl of water and sprinkling flour or oats on the surface. of the water
The cockles take in the flour and "spit out any grit that they contain", accoding to Hairy Biker ( I like the style of these two guys because they believe in real food).
So, this is why I ask the question.
Are shellfish often treated like this to purge them? Does it include mussels ( memories of a kid and my mum 'cleaning out' live mussels with flour and water). If the shellfish are fed with flour, do they retain some gluten, thus making them unsuitable for coeliacs?
Just a thought.....