The toxic level October 17, 2008

The Food and Drug Administration (FDA) is set up the regulation of histamine level in fishery, because histamine is generally not uniformly distributed in a decomposed fish.

The defect action level of histamine, the level at which regulatory actions are taken, is set at 5 mg/100 g (50 ppm). If 5 mg/100 g is found in one section of foods, there is the possibility that other units may exceed toxicity level, 50 mg/100 g (500 ppm) (FDA 1996). While maximum average histamine content of 10 mg/100 g (100 ppm) has been established in the European Community (EC) for acceptance of tuna and other fish belonging to the Scombridae and Scomberesocidae families.

Microbial producing biogenic amines

Several studies have shown that Morganella spp., Proteus morganii, Proteus spp., Hafnia alvei, and Klebsiella spp. are able to produce histamines and other biogenic amines. There is potentiality of these microorganisms to produce toxic levels of biogenic amines.

There are many studied of biogenic amine formation by bacteria growing on media cultured and fish. 

 

 

Toxicity of biogenic amines and detoxification

Normally, during the food intake process in the human gut, low amounts of biogenic amines are metabolized to less active degradation products. This detoxification system includes specific enzymes (e.g. diamine oxidase DAO). However, upon intake of high loads of biogenic amines with foods, this detoxification system is unable to eliminate biogenic amines sufficiently. Moreover, in case of insufficient DAO-activity, caused by e. g. genetic predisposition, gastrointestinal diseases, or inhibition of DAO-activity due to secondary effects of medicines or alcohol, already low amounts of biogenic amines cannot be metabolized efficiently. Biogenic amines are readily absorbed and get into circulation, leading to toxic effects. Besides DAO, monoamine oxidases (MAO) distributed in different tissues of the human body also participate in the physiological inactivation of biogenic amines. Certain drugs (MAO-inhibitors) are decrease the activity of MAO, leading to an increased risk after intake of food contaminated with biogenic amines.

Biogenic amines such as histamine, in high concentrations are risk factors for food intoxication, whereas moderate levels may lead to food intolerance. The toxicity of histamine appeared to be enhanced by the presence of other amines such as cadaverine, putrescine, and tyramine. Several outbreaks of histamine poisoning have occurred after eating cheese or fish Sensitive persons, with insufficient diamine oxidase activity, suffer from numerous undesirable reactions after intake of histamine containing foods. Furthermore, secondary amines such as putrescine and cadaverine can react with nitrite to form heterocyclic carcinogen nitrosamines; nitrosopyrrolidine and nitrosopiperidine, respectively. Therefore, biogenic amines are concerned in relation to food spoilage, food safety, and food intolerance, and their content in foods should be as low as possible. The most frequent foodborne intoxications and intolerances, caused by biogenic amines, involve histamine.

Histamine exerts its toxicity by interacting with the receptors on cellular membranes. There are three types of histamine receptors, H1, H2 and H3. The most common symptoms result from action on the cardiovascular system. Histamine causes dilatation of peripheral blood vessels, causing urticaria, hypotension, flushing and headache. Histamine-induced contraction of intestinal smooth muscle causes abdominal cramps, diarrhea and vomiting. Pain and itching associated with the urticarial lesions may be due to sensory and motor neuron stimulation. 

 

What’s biogenic amine

Biogenic amines are organic, nitrogenous compounds received from decarboxylation of amino acids or transamination of aldehydes and ketones. They have low molecular weights and are found in microbial, vegetables and animal metabolisms. Biogenic amines in raw and processed foods and beverages are synthesized by the reaction of enzymes in their raw materials or microbial decarboxylation of amino acids. Free amino acids are decarboxylated by decarboxylase enzymes that specific to their precursor.

Factors that affected biogenic amines formation by microorganism are:

·      Availability of free amino acids precursor

·      Presence of decarboxylase-positive microorganisms such as several groups of microorganisms, mainly Entheterobacteriaceae, Pseudomonas spp., enterococci and some lactic acid bacteria.

·       Conditions that allow bacterial growth, decarboxylase synthesis and decarboxylase activity such as fermentable sugars, pH, redox potential and etc.

 

 

Biogenic amines in foods

Foods containing protein or free amino acids are subject to conditions enabling microbial or biochemical activity biogenic amines can be expected. The total amount of different biogenic amines depends on nature of foods and the microorganisms present. Biogenic amines are present in a many types of food product such as fish products, meat products, dairy products, wine, beer, vegetables, fruits, nuts and chocolate. Their concentrations vary extensively not only between different food varieties but also within the varieties themselves.

Biogenic amines have sometimes been related to spoilage and fermentation processese especially, fish belonging to the families Scomberesocidae and Scombridae. Fish included in these families are the tunas, bonito, mackerels, bluefish, and saury. Some biogenic amines such as histamine and tyramine in high level associate to food poisoning. Some biogenic amines can be converted to nitrosamine by nitrosation.

The presence of biogenic amines in foods that higher than certain level is considered as undesired microbial activity. Therefore, the amines level could be used as indicator of microbial spoilage. Levels of histamine, putrescine and cadaverine usually increase during fish and meat spoilage while levels of spermine and spermidine decrease.