Microbial survival in gourmet hamburger thermally processed by different degrees of doneness

Consumption of gourmet hamburgers expressively increased worldwide. However, some core temperatures used in its preparation do not reach the cooking limits recommended by regulatory agencies. This study aimed to assess the microbial reduction in a standardized gourmet hamburger submitted to different degrees of doneness. Raw patties were artificially contaminated with a pool of Escherichia coli (8 log CFU/g) and were quantified after thermally processed in different degrees. Counts were modeled by GInaFiT software using the Weibull model. Mesophilic microorganisms were analyzed and MALDI-TOF/MS identified the survivors. Color and texture were analyzed after each thermal process. Maximum reductions of mesophilic counts (4.3 log CFU/g) and E. coli (4.8 log CFU/g) were obtained at 77 °C after 14 min (well-done degree). Recommendation of 5 log-E. coli reduction was not reached by any degree and only was reached when the patties had 81 °C after 16 min (very well-done degree), but color and texture were negatively altered. Kinetic parameters showed a strong correlation between experimental data. MALDI-TOF/MS showed low diversity of survivors in hamburgers. Thus, the safety and quality of gourmet hamburgers depend on the microbiological quality of ground meat used and validate the thermal process considering specific conditions of each food service.