How Freezing, Thawing and Cooking Affect Pathogens in Beef Patties04 May 2015
Frozen storage of ground beef that has been contaminated with E.Coli 0157:H7 enhances the survival of the pathogen.
A team of researchers from Cranfield University in the UK and the Agricultural University of Athens in Greece looked at the effect of frozen storage, different thawing methods and cooking processes on the survival of pathogens in commercially shaped beef patties.
The effect of common handling practices such as freezing, thawing and cooking of the beef patties on the survival of Salmonella spp. and Escherichia coli O157:H7, was evaluated.
Inoculated ground beef was stored at –22 °C for five and 75 days.
After thawing at 4°C for 16 hours, 20°C for 12 hours and in a microwave for 22–24 minutes, or without prior thawing, beef patties (90 g) were shaped and cooked in an oven-broiler or in pan-grill to internal temperatures of 60°C or 71°C.
Cooking in the oven-broiler was more effective compared to the pan-grill, especially when cooked to 71 °C.
Defrosting methods did not affect significantly (P ≥ 0.05) the survival of the pathogens during subsequent cooking.
However, the team of Stavros G. Manios and Panagiotis N. Skandamis found that frozen storage for 75 days enhanced the survival of E. coli O157:H7, as the pathogen survived 3.1 log CFU/g when cooked in an oven-broiler at 71 °C.
They said that the results may supplement the existing guidelines for the appropriate practices, associated with freezing, thawing and cooking of patties in households or catering services.
The research appears in Science Direct.
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