Biogenic amine production from processed animal and plant protein-based foods contaminated with Escherichia coli and Enterococcus feacalis

The aim of the study was to investigate biogenic amine production in different types of cooked protein foods. The food samples were incubated at varying temperatures (4, 37 and 55 degrees C) on different microbiological media for 48, 72 and 180 h. Resulting bacteria were isolated and characterized using cultural, biochemical and molecular methods, further screened for production of biogenic amines in decarboxylase broth media supplemented with 0.4% of histidine, tyrosine, lysine and ornithine. The samples were incubated at 25 degrees C for 48 h and the biogenic amine concentration in each food sample determined by means of HPLC. There was a high prevalence of the isolates among the food samples. All the isolates except Klebsiella sp. and Pseudomonas sp. were positive for decarboxylase activity indicating 84.6% of the isolates capable of biogenic amine production. The amine concentration varied among the types of food and methods of cooking. Histamine was detected in 41.67% of the inoculated food samples (9.2 +/- 1.2-100.95 +/- 0.1 mu g/g) while putrescine was the least detected (41.67%) in the inoculated food sample (7.7 +/- 0.1-8.8 +/- 0.2 mu g/g). Cadaverine and histamine were detected in 16.4% (2.6 +/- 0.2-49.9 +/- 0.9 mu g/g) and 7.5% (1.4 +/- 0.1-20.4 +/- 0.3 mu g/g) of the foods, respectively. Microbial contamination of the cooked protein foods led to high levels of biogenic amines irrespective of the cooking methodology adopted and type of foods investigated.