Reduction of Bacterial Populations by Surface Flaming in Beef Trim Utilized for Ground Beef Patties in Food Service Operations

Semitendinosus muscles from low quality, cull cows were trimmed, separated into three fat levels (10, 20, and 30%), treated with 0, 5, 10, 15, or 20 seconds of surface flame application, ground, and formed into patties. Patties were quick frozen (-80 C for 1 hr) and stored at -10 C for 0, 4 or 24 days. Hunter “L” and “b” values increased (P<.01) and Hunter “a” values decreased (P<.01) as flame time increased. Metmyoglobin and discoloration percentages increased (P<.05) as flame time increased. High fat patties (30%) had lower cook losses (P<.01) as flame time increased due to initial fat loss whereas low fat patties (10%) had constant cook losses. Water-holding-capacity increased (P<.05) at extreme flame time (20 secs) in all patties. Juiciness and tenderness scores were significantly decreased and flavor intensity increased in lean patties as flame time increased. Juiciness and tenderness scores in high fat patties were not affected but patties had lower cohesive scores as flame time increased. Aerobic, anaerobic, lactic acid producing, and psychrotrophic bacteria, within each fat level, decreased as flame time increased from 0 to 10, 15, or 20 secs. Temperature abused patties had significantly higher (P<.01) bacterial populations than original populations of control patties at each fat level. These data indicate surface flaming initially reduces bacterial populations and minimizes bacterial growth without adverse physical damage to the product. Unfortunately, this method of bacterial reduction is not as effective in patties which are temperature abused.