How to tell when mussels aen’t safe to eat: a practical guide for recognizing the key warning signs

The first warning sign. A fresh mussel must be alive. If you see it open raw, tap it: it has to close. If it doesn't, it is dead and not fit for consumption.

Good mussels smell of clean and fresh sea. If it gives off a strong, ammonia or unpleasant smell, it is best to discard it. Remember that aroma is a reliable indicator of the condition of the shellfish.

Mussels can accumulate toxins from microalgae. These substances are not eliminated when cooked. That is why harvesting is controlled in producing areas such as Galicia. Always buy in regulated markets and with official labeling.

A cracked shell facilitates the entry of bacteria. A good mussel should be whole, closed and with a moist shine. If it does not meet these conditions, reject it.

Mussels lose quality and safety if mishandled. Cooking them too long makes them rubbery, but the most dangerous thing is to leave them at room temperature for hours: bacteria such as E. coli or Vibrio can appear. It is advisable to eat them freshly cooked and keep leftovers cold as soon as possible.

Another rule of thumb: if after cooking or steaming any mussels remain closed, discard them without hesitation. It means that it was not alive when it entered the pot and is not safe to eat.

Fresh mussels should be kept in the refrigerator, covered with a damp cloth and never in closed plastic bags, because they suffocate. After cooking, they should be refrigerated as soon as possible in a covered container and consumed within 24 hours.

For decades it was said that shellfish should only be eaten in months with "R" (from September to April). Today that rule has lost its value, because purification and refrigeration systems guarantee the safety of mussels all year round. It remains as a cultural memory, but not as a consumption rule.