Tip of the Week

Did you know that leaving fish to defrost at room temperature, or in water in a sink, can cause a person to have an allergic reaction even when the fish is fully cooked?

A common form of food poisoning attributed to fish is Scombroid food poisoning.  The symptoms of this type of food poisoning are similar to having an allergic reaction.

Fresh fish needs to be frozen at source or kept at very low temperatures as the flesh starts to spoil at the relatively low temperature of 16°C.

Histamine is a naturally occurring amino acid that is present in fish. At temperatures above 16°C (it is not often a kitchen temperature will be below 16°C), histamine is converted into biogenic amine histamine which results in Scombroid food poisoning.

Kitchens are hot places so, if you defrost fish in the kitchen, or in water in the sink, it is likely the outside flesh will reach 16°C or above, and so a build-up of histamine occurs.  Histamine can occur in fresh fish from temperatures as low as 7°C; however it is more likely to occur at temperatures of 16°C or above.

This Histamine is not destroyed by normal cooking temperatures, so if the fish has been defrosted at room temperature and is then properly cooked, it can still result in poisoning.

Histamine is also the natural chemical responsible for true allergic reactions and, as the symptoms produced by scombroid food poisoning are similar, it often gets misidentified as a food allergy.


Always defrost fish in the refrigerator under controlled temperature conditions.  The outside temperature of the fish will easily rise to 16°C if defrosted in a sink of water or a warm kitchen.

Weekly Food Fact

Want to be brainy – eat fish.  Fish is one of the healthiest foods you can eat.  It is loaded with nutrients such as protein and vitamin D.  It is also the world’s best source of omega-3 fatty acids, which are incredibly important for your body and brain.

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