Microbiological Evaluation of Precooked Beef Patties Containing Soy Protein

Beef patties of seven formulations, six containing soy protein concentrate and/or textured vegetable protein, were frozen either raw or immediately after they were precooked to an internal temperature of 60–65°C. Addition of soy protein had no effect of any practical significance on the microflora of the raw or precooked patties. Precooked patties of all formulations contained significantly (P < 0.05) lower aerobic plate counts (20° C) and MPN's of coli‐forms, fecal coliforms, Escherichia coli and Staphylococcus aureus than the raw patties. E. coli and S. aureus could not be detected in 90% of the precooked patties. Clostridium perfringens was not detected in any of the precooked patties and was found in very low numbers in only 7% of the raw patties. Salmonellae were not detected in either the raw or precooked patties.