Freezing Technology

8.4.1 Biogenic Amines

            Histamine poisoning is a chemical intoxication following the ingestion of foods that contain high levels of histamine. Historically, this poisoning was called scombroid fish poisoning because of the frequent association with scombroid fishes including tuna and mackerel. The most common symptoms are cutaneous such as facial flushing, utricaria, edema, but also the gastrointestinal tract may be affected ( nausea, vomiting, diarrhea) as well as neurological involvement ( headache, tingling, burning sensation in the mouth).

          Histamine is formed in the fish post mortem by biological decarboxylation of the amino acid histidine. 

          The histamine-producing bacteria are certain enterobacteriaceae, some Vibrio sp. A few Clostridium and lactobacillus sp.  The most potent histamine producers are Morganella morgani, Klebsiella  pneumoniae and Hafinia alviei ( Etratten and Taylor, 1991). These bacteria can be found on most fish, probably as a result of post-harvest contamination they grow well at 10^o C but at 5^o C growth is greatly retarded.          

          The principal histamine producing bacteria M.morganii grow best at neutral pH, but they can grow in the pH range 4.7-8.1.The organism is not very resistant to NaCl, but at otherwise optimal conditions growth can take place in upto 5% NaCl. It should be emphasized that at once the histamine has been produced in the fish, the risk of provoking disease is very high.  Histamine is very resistant to heat, so even if the fish are cooked, canned or otherwise heat-treated before consumption, the histamine is not destroyed.

          The human body will tolerate a certain amount of histamine without any reaction ingested histamine will be detoxified in the intestinal tract by at least 2 enzymes the diamine oxidase (DAO) and histamine N-methyl transferase (HMT) (Taylor, 1986).

          Their protective mechanism can be eliminated if intake of histamine and / or other biogenic amines is very higher if the enzymes are chocked by other compounds as shown in figure. Other biogenic amines such as cadaverine and putriscine which are known to occur in spoiled fish may therefore act as potentiators of histamine toxicity.  Presumably inhibition of intestinal histamine catabolism will result in greater transport of histamine across cellular membrane and into the blood circulation.