Histamine and Histamine-Producing Bacteria in Retail Swiss and Low-Salt Cheeses.

Seventeen low-sodium and low-salt cheeses and 50 Swiss cheeses were surveyed for histamine and histamine-producing organisms. Two of the low-salt cheeses and nine of the Swiss cheese samples contained greater than 45 mg histamine per 100 g of cheese, as determined by the AOAC method. Over 800 total colonies were randomly chosen and screened for histamine production by the leucocrystal violet detection method following their initial isolation from MRS media. However, none of the leucocrystal violet-positive isolates from the low-salt cheese and only five from the Swiss cheese were found to produce histamine in MRS broth supplemented with L-histidine. Proteolysis (determined by the trinitrobenzene-sulfonic acid assay) was also measured in the low-salt cheeses in an attempt to further understand the role of free histidine as a substrate with respect to histamine content. In general, the cheese samples with high histamine levels also had the high values for trichloroacteic acid-soluble nitrogen. However, the highest proteolysis values did not necessarily correlate with the highest histamine values. Two samples of low-salt Swiss cheese that had high trichloroacetic acid-soluble nitrogen (greater than 200 µmoles glycine equivalents per g of cheese) contained less than 15 mg histamine per 100 g cheese.

Biogenic Amines in Cheese and other Fermented Foods: A Review.

The biogenic amine content of various foods has been widely studied because of their potential toxicity. Biogenic amines, such as tyramine and ß-phenylethylamine, have been proposed as the initiators of hypertensive crisis in certain patients and of dietary-induced migraine. Another amine, histamine, has been implicated as the causative agent in several outbreaks of food poisoning. Histamine poisoning is a foodborne chemical intoxication resulting from the ingestion of foods containing excessive amounts of histamine. Although commonly associated with the consumption of scombroid-type fish, other foods such as cheese have also been associated with outbreaks of histamine poisoning. Fermented foods such as wine, dry sausage, sauerkraut, miso, and soy sauce can also contain histamine along with other biogenic amines. Microorganisms possessing the enzyme histidine decarboxylase, which converts histidine to histamine, are responsible for the formation of histamine in foods. One organism, Lactobacillus buchneri , may be important to the dairy industry due to its involvement in cheese-related outbreaks of histamine-poisoning. The toxicity of histamine appears to be enhanced by the presence of other biogenic amines found in foods that can inhibit histamine-metabolizing enzymes in the small intestine. Estimating the frequency of histamine poisoning is difficult because most countries do not regulate histamine levels in foods, nor do they require notification when an incident of histamine poisoning occurs. Also, because histamine poisoning closely resembles a food allergy, it may often be misdiagnosed. This review will focus on the importance of histamine and biogenic amines in cheese and other fermented foods.

Histamine Production in Low-Salt Cheddar Cheese.

To assess the potential for histamine production in low-salt Cheddar cheese, pasteurized milk was inoculated with Lactobacillus buchneri St2A at levels of 102, 103, and 104 microorganisms per ml of milk. One additional vat was uninoculated and served as a control. Milk was then manufactured into low-salt (0.40%) Cheddar cheese. After 180 d of aging at 7°C, levels of L. buchneri St2A had increased approximately 100-fold in the inoculated cheese. Proteolysis, expressed as µmoles free glycine per g cheese, increased from 40 to 150 (trichloroacetic acid soluble) and from 25 to 130 (phosphotungstic acid soluble) during the ripening period. Histamine levels, however, remained low in the inoculated cheeses (<5 mg/100 g), suggesting that the potential for histamine formation may be minimal in low-salt Cheddar cheese. It was concluded that the relatively low levels of proteolysis and low temperature of storage were primarily responsible for inhibiting histamine production.