Abstract: E.coli O157:H7 was first isolated in 1982 in relation to a hemorrhagic colitis outbreak due to consumption of insufficiently cooked hamburgers. The aim of this work was to assess the effect of different temperatures and storage times on E.coli survival and production of Shiga toxins in hamburgers experimentally contaminated with enterohemorrhagic E.coli. The hamburgers were stored at 4�C for 7 days and at 0�C and -20�C for 30 days. Bacterial cell counts were carried out before and after storage and toxicity was assayed. Similarly, Shiga toxins were determined at different storage temperatures and time intervals. Bacterial survival after storage at 4�C was >60% and at 0�C 65% after 7 days, diminishing to 20% after 30 days of storage. At -20�C survival was 55% after 7 days and 40% after 30 days of storage. In all the cases they maintain its virulence factors (toxin production).These results suggest that hamburgers, although stored at low temperatures, need excellent manufacturing processes. Besides, maintaining the cooling chain uninterrupted is absolutely necessary to assure the hamburgers are safe for consumption.
M.A. Jure , O. Aulet de Saab , A. Suarez and M.C. de Castillo , 2006. Assessment of Survival and Production of Shiga Toxins by Enterohemorrhagic E. coli in Stored Hamburgers. Journal of Food Technology, 4: 194-199.