After several months of being away from my blog, due to lots of work to do, I am back and happy, because, to be honest, I have been missing to write and discuss about chemistry! This week end I was talking to some students about the role of the chemists in the food control, quality control of food production and research and development in the food industry. I introduced the HACCP system and reported some examples about food control in some types of industries. One of the most interesting topics, was about the histamine fish poisoning. Histamine fish poisoning (or Scombroid poisoning) is a type of food poisoning caused by elevated levels of histamine being present in the fish. Naturally occurring bacteria in fish produce an enzyme which converts histidine in the fish to histamine. Histamine fish poisoning usually occurs in certain species of fish, such as tuna, sardines, mackerel, swordfish and marlin, because of their high content of histidine. Histamine fish poisoning occurs very quickly after eating the fish, usually within 30 minutes to a few hours.
Common signs of histamine fish poisoning include: a peppery taste sensation, skin rash, headaches, dizziness and itching of the skin.
In some cases nausea, vomiting and diarrhoea may also occur. Symptoms usually last for 4 to 6 hours and rarely exceed one day. It is easily treated with an antihistamine.
Histamine is not destroyed by cooking. Therefore, the best way to keep histamine at a minimum is to ensure proper temperature control and good practices and hygienical conditions during the preparation of fish.
In some cases, low levels of histamine may already be present in the fish when you receive it. To stop it increasing to levels of concern, you should always:
1) purchase from reputable suppliers who store the fish on ice or under refrigeration;
2) receive product at refrigerated temperatures (<5°C);
3) place the fish under refrigeration as soon as it is received;
4) keep the fish at refrigerated temperatures when not being used; and
5) if the fish is frozen, thaw the fish under refrigeration.
When displaying fish for sale, always ensure there is enough ice on the product and refrigeration units are set at a temperature less than 5°C.
If you produce fish products (anchovies under oil, with capers, or with tomatos and other types of food), follow good hygiene practices:
1) Keep the surfaces and all the things you use clean;
2) Dress clean coats and use protections for hands to avoid the risk of contaminations.
Anyway, there is a big world about the fish industry and several things can be written, I think I will be back to this argument, in the future, may be with some recipes about fish!
