Biogenic amines found in food have harmful effects on the health of the population: histamine toxicity, "histamine intolerance" and "cheese reaction". The maximum permitted intake (EFSA, 2011) for histamine and tyramine has been set respectively at 25-50 mg and 600 mg in healthy individuals, and at 0 mg and 6-50 mg for all other individuals.

Biogenic amines are produced in cheese by the action of certain microorganisms (e.g. Lactobacillus parabutcherii) by decarboxylating the amino acids histidine and tyrosine that have previously been released from the milk protein fraction through proteolysis. Thus, the cheeses with the highest levels of these compounds are those with high proteolytic activity: blue cheeses (490 g/kg histamine and 625 g/kg tyramine) and pressed cheeses (cooked - 210 g/kg histamine and 41 g/kg tyramine; or uncooked - 25.6 g/kg histamine and 238 g/kg tyramine).

However, not all microorganisms in cheese are capable of producing these compounds, and, more significantly, there are other important microorganisms found in the cheese industry that are capable of degrading histamine and tyramine (e.g. Lactobacillus casei), thus removing their toxic component from the food.

Thanks to its strategic position in the dairy sector through Leartiker S. Coop., the Leartiker Dairy Centre has installed massive sequencing equipment in the microbiology laboratory, which is capable of quickly and efficiently identifying the complete microbiome of a cheese. Hence, the proposed project will identify the histamine and tyramine-producing bacteria in cheeses with high proteolytic activity (blue cheeses and pressed cheeses) and, in turn, determine the quantities of biogenic amines present in commercial cheeses and whether this jeopardises food safety.

• Leartiker S.Coop.

• Conducting a literature review to identify the levels of histamine and tyramine frequently found in cheeses with high proteolytic activity, the associated bacterial flora and the factors that increase their concentration.
• Determining the levels of histamine and tyramine present in commercial and farm-produced blue and pressed cheeses, as well as establishing the composition of their microbiota.
• Conducting a literature review with a view to reducing the levels of histamine and tyramine present in blue cheeses and pressed cheeses by promoting the growth of the cheese's own or external bacteria that degrade these biogenic amines.