Effectiveness of two cooking systems in destroying Escherichia coli O157 :H7 and Listeria monocytogenes in ground beef patties

A rapid, high-temperature double-sided grilling-broiling (DGB) system was c ompared to a single-sided broiling (SSB) system for cooking of foodservice ground beef patties to reduce microbial numbers and maintain textural quali ty. Patties (110 g) containing either Escherichia coli O157:H7 or Listeria monocytogenes (10(6-7) CFU/g) were cooked to target internal temperatures o f 60 or 68 degrees C on each cooking system and immediately removed from th e grills without the additional holding time at 60 or 68 degrees C that is recommended for foodservice cooking of ground beef patties. Actual find int ernal temperature attained, position on the grill, degree of doneness, cook ing time, after-cook weight, texture characteristics, and bacterial counts of the patties were monitored. The DGB reduced E. coli O157:H7 and L. monoc ytogenes populations in ground beef patties by 5.7 log(10) and 5.4 log(10) CFU/g, respectively, when cooked to a target temperature of 60 degrees C (a ctual final internal temperature of 71.2 degrees C) and by 6.1 log(10) and 5.6 log(10) CFU/g, respectively, when cooked to a target temperature of 68 degrees C (actual final internal temperature of 75.8 degrees C). The SSB re duced E. coli O157:H7 and L. monocytogenes populations by 1.3 log(10) and 1 .8 log(10) CFU/ g, respectively, when cooked to a target temperature of 60 degrees C (actual final internal temperature of 62.7 degrees C) and by 2.9 log(10) and 3.6 log(10) CFU/g, respectively, when cooked to a target temper ature of 68 degrees C (actual final internal temperature of 69.3 degrees C) . The DGB system effected a higher, more rapid temperature increase in patt ies cooked to either target temperature compared to the SSB system. This hi gher temperature was more effective in destroying pathogens in beef patties . Texture analyses determined that patties cooked on the DGB system had sig nificantly higher values for springiness, adhesiveness, and product height as compared to the SSB system, and patties cooked on either system had sign ificantly higher hardness, gumminess, chewiness, and product height values at the target temperature of 68 degrees C as compared to 60 degrees C.