Biogenic amines in cold-smoked fish fermented with lactic acid bacteria

It has been proved in previous studies that fish can be fermented by lactic acid bacteria (LAB). Added glucose must be ai concentrations of almost 1% to reduce the pH to < 5.3, a level which corresponds to the safe pH values for meat products. Because some LAB and some contaminating microbes form biogenic amines, this study was conducted to examine the possible formation of biogenic amines during the fish fermentation process. Other parameters under study were sensory quality, pH value, titrated acid content, weight loss, a(w) value, redox potential and microbiological counts. Three groups of fish (rainbow trout) with three different LAB inocula and a group without any inoculum were made. The fermentation of the products made with LAB succeeded. The products were sensorially accepted, the inoculated LAB grew to >8 log cfu/g, the pH reduced to 5.0-5.3 and a(w) to 0.927 and the pseudomonads the predominant flora of fish raw material, disappeared. The fish raw material and the products contained low amounts of biogenic amines with one exception: cadaverine, histamine and tyramine increased in all product groups in one experimental series (II) out of three. The highest concentrations of these amines were in the control products without any LAB inoculation. The LAB used and the contaminants isolated from the products were unable to produce cadaverine, histamine or tyramine. The appearance of these amines could therefore be caused by the non-isolated contaminants of fish raw material.