Escherichia coli O157:H7 and Salmonella spp. risk assessments for the production and cooking of restructured beef steaks

Meat restructuring enables good quality meat trimmings to be bound into larger sized portions. However, the microbiological risk associated with restructured beef production has not been extensively studied. Furthermore, restructured beef steaks are cooked to varying degrees of doneness; considering that the incidence of food-borne outbreaks with Escherichia coli O157:H7 and Salmonella spp. have been attributed mostly to inadequate cooking, there is a need to assess the safety of non-intact meat cuts.; Our objectives were to quantify E. coli O157:H7 and Salmonella spp. relocation in restructured meat, and evaluate their reduction by two traditionally used cooking methods, to ascertain the level of safety associated with these products.; Longissumus dorsi trimmings were inoculated with green fluorescent protein-S65T (GFP-S65T) expressing E. coli O157:H7 or GFP-S65T Salmonella spp. to determine bacterial translocation in Fibrimex restructured meat cross sections, through confocal laser scanning microscopy. Alongside, for translocation and cooking survivors estimation, an E. coli O157:H7 six-strain mix or Salmonella spp. six serovars mix were inoculated to an initial level of 107 CFU/g in beef trimmings followed by restructured steaks format.; Restructured steaks of three thickness (1.27, 2.54 and 3.81 cm) were cooked to one of six internal temperatures (48.8, 54.4, 60, 65.5, 71.1, or 76.6°C). E. coli O157:H7 recovery was calculated after plating on MacConkey Sorbitol and Phenol Red Sorbitol agars. Salmonella spp. was recovered by plating, on Xylose Lysine Deoxycholate and Xylose Lysine Deoxycholate Reduced agars, for 3.81 cm restructured beef steaks cooked similarly as in the E. coli O157:H7 study.; Cross-sectional microscopic visualization showed E. coli O157:H7 or Salmonella spp. fluorescence density along the joining bands where meat pieces were enzymatically cross-linked with Fibirmex. Additionally, microbial enumeration showed bacterial translocation evenly distributed within the restructured steaks (approx. 106 CFU/g). As expected, E. coli O157:H7 and Salmonella spp. survivals decreased as endpoint temperatures for grilled and broiled steaks were incrementally increased and significant differences (p ≤ 0.05) in cooking effectiveness were observed.; These results suggest that restructured beef products, as non-intact muscle steaks, should be cooked in a similar manner as ground beef (>71.1°C) per USA recommendations, unless a validated antimicrobial intervention treatment is used to decontaminate beef trimmings being used in the restructuring process.