Hazards In Scombroid Fish

H. Mandakini Devi / Gaihiamngam Kamei *

All foods contain microorganisms, some are beneficial and some are harmful for mankind. The toxins formed by some bacteria poses big threats for our well being as most of us enjoy eating fish. Scromboid fish such as mackerel, tuna contains large amount of histidine (amino acid) in the muscle. The decarboxylation of histidine by some group of bacteria leads to the formation of histamine. Histamine poisoning is a significant public health and safety concern.

In the intestinal tract of mammals dietary intake of histamine can be detoxified by the action of amine oxidase , such as Monoamine Oxidases(MAO),diamine oxidase(DAO).But when the in take is more the detoxification process becomes less efficient ,thus histamine accumulate in the body.

Histamine is the causative agent of scromboid poisoning. Scromboid/histamine poisoning is a food borne chemical intoxication cause by the ingestion of food containing high level of histamine. Scromboid poisoning usually occurs throughout the world. It is a mild disease but sometimes it can be serious with cardiac and respiratory implications.

The fish are harmless when it is fresh but the important thing is that the fish may have normal appearance and odor though it has become toxic. Some psychrophillic bacteria can produce histamine at temperature as low as 2.5°C. So this shows that low temperature are not sufficient to prevent the formation of histamine. There is no cooking, refrigeration, and freezing and canning methods known so far that can destroy histamine once it has formed.

HISTAMINE FORMATION IN FISH

Biogenic amine (histamine) is low molecular weight compound. Small quantity are synthesizes in the animal and plants cells but in food they are produced in larger quantities by microbial degradation of amino acids. Enterobacteriacea is primarily responsible for decomposition of scromboid fish and the most potent producers of histamine.

These toxicity varies with individual capacity of intoxication for sensitive individuals the toxin can pose health risk. Histamine is formed after the death of the fish due to proliferation of certain bacteria which can synthesize histamine decarboxylase. Histamine decarboxylase is an enzyme which can convert histidine to histamine.

HISTAMINE FORMING BACTERIA

Several species of enteric bacteria and naturally occurring marine bacteria have been found responsible for the formation of histamine. Among the identified histamine forming bacteria, the most important species are mentioned below:
Morganella morganii, Klebsiella pneumoniae, and Hafnia alvei

Histamine former is most prevalent in fish at 25°C. Morganella morganii is the main contributor to histamine formation in fish. Histamine increased rapidly and reached the highest level of 286mg/100 g in 2 days. The guideline for histamine in fish and fishery product is 5 mg/100 g (according to USFDA). Histamine production is controlled when the storage temperature of Scombroid fish is maintained around 0°C or below.

Several investigators have shown that, fish subjected to storage at 20°C for a short period of time will yield high levels of histamine even though the fish had initially been stored at low temperature. Histamine is one of the most toxic amine. The incubation period is very less ranging from few minutes to few hours after consumption of toxic fish. Some people recover from the poisoning within 24 hours but some suffer for long time because of sensitivity differences of histamine in individuals.

The symptoms of histamine poisoning generally resemble the symptoms encountered with IgE-mediated food allergies. The symptoms include nausea, vomiting, diarrhea, an oral burning sensation or peppery taste, hives, itching, red rash, and hypotension. The onsets of the symptoms usually occur within a few minutes after ingestion of the implicated food, and the duration of symptoms ranges from a few hours to 24h. Antihistamines drugs can be used effectively to treat this intoxication.

Foods with histamine concentrations exceeding 50mg per 100g of food are generally considered to be hazardous.

Once histamine is formed it does not go away and no amount of washing or cooking will remove or destroy it. Likewise, freezing will not reduce or destroy histamine after it has formed. Prevention is the only way to assure that histamine is not in the fish in the first place.

WHAT WE CAN DO TO PREVENT THE FORMATION OF HISTAMINE

Rapid cooling and removing the gut to reduce the bacteria that can cause histamine is the key to prevent the formation of Scombroid fish poisoning.

INSTRUMENTS FOR DETERMINATION OF HISTAMNE IN FOOD

These amines can be determined by thin layer chromatography, Gas Chromatography, Ion Exchange Chromatography, High Performance Liquid Chromatography. The recent more advanced technique is the Ultra Performance Liquid Chromatography. These are costly instrument and small fish retailer cannot afford to measure histamine contain in the fish load coming from outside states.

REMARK

The innocent consumer has nothing to do with the quality control of such fish. The fish handler starting from onboard to retailer have the sole responsibility to keep the fish chill at low temperature till it reaches the consumer point. It is necessary to have a quality control laboratory and distribute only those fish which are below the hazardous level of histamine to the consumers.

In view of potential hazards from the consumption of scrombroid fish we need to developed and implement stringent safety regulations while handling, transportations and storage.