Biogenic amines and microbial growth on hamburgers meat

The objective of this work was to determine the effect of temperature and storage time on aerobic mesophilic bacteria and enterobacteria potentially producer of biogenic amines, in two brands (A and B) of hamburger's meat. Fifty six (56) samples were purchased and stored at -10, 4 and 10degreesC during 96 hours. A sample was taken from each temperature at the 0 (less of six hours of preparation), 48 and 96 hours, to count aerobic mesophilic bacteria (RAM), and enterobacteriaceae according ICMSF. Enterobacteriaceae colonies were tested for their identification. Biogenic amines concentration was determined by high performance liquid chromatography. The highest RAM for brands A and B was produced at 10degreesC and 96 hours, 5.83 and 6.86 log UFC/g; and the lowest values were found at time 0, being 5.06 for brand A, and 4.91 for brand B. Significant differences (P<0.05) were found at 4 and 10degreesC in enterobacteria count from 48 hours in both brands. Potentially biogenic amine producing enterobacteria were identified: Citrobacter freundii, Escherichia coli, Enterobacter cloacae, Enterobacter agglomerans, Enterobacter aerogenes, Hafnia alvei, Klebsiella pneumoniae. Espermine, espermidine, cadaverine and serotonine were detected in concentrations lower than the maximum allowed values (200-500 ppm). In conclution, significant increases in aerobic mesophilic and enterobacteria counts were detected for both brands of hamburguer meat stored at 4 and 10degreesC from 48 hours. Although biogenic amine producing enterobacteria were found, they didn't exceed allowed limits.