Effect of stress factors on the production of biogenic amines by lactic acid bacteria isolated from fermented Mexican foods (cheese and beer)

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The growth of lactic acid bacteria (LAB) in fermented foods, especially in ripened foods, could be associated with the production of biogenic amines (BAs). BAs are small, nitrogen-containing, thermostable, non-volatile organic compounds, which can induce toxic effects in food consumers. This work aimed to determine potential BAs-producer LAB strains isolated from ripened cheese and beer and to evaluate stress factors that induce the production of these metabolites. Determination of BAs-related genes in eighteen strains of LAB was done by polymerase chain reaction (PCR). The effect of pH, NaCl concentration and ethanol concentration on the LAB growth and BAs production was evaluated. The concentration of BAs (histamine, tyrosine, putrescine and cadaverine) was determined by high performance liquid chromatography (HPLC). Additionally, survival of selected LAB strains during beer making process was evaluated. All LAB strains could tolerate concentrations of 4 and 6 mL/100 mL of ethanol. More than one strain showed the ability to produce all the BAs studied and all beer strains were able to produce Tyramine. The pH level was the most influent factor in BAs production; pH 4 was optimal for the production of histamine (cheese and beer strains) and pH 5 for tyramine (beer strains). LAB population showed a 2-log reduction along the two initial days of fermentation. At the end of the beer making process 1.6 log of LAB were recovered. BAs production has been considered a mechanism that increases bacterial survival against acidic environment. Some LAB strains in fermented products may represent a health risk for consumers. Sanitary practices during food production and raw material quality should be complement measurements to a good control of fermentation process to minimize BAs presence in foods.