One steam-vacuuming unit (Unit A) was evaluated for removal of visible contamination and reduction of bacterial counts on beef carcass surfaces in five processing plants; a second steam-vacuuming unit (Unit B) was evaluated in two of those same plants at a later date. Experimental treatments included appropriate Controls: steam vacuuming carcass surfaces with or without visible contamination, and knife trimming surfaces with visible contamination. Depending on the processing plant, carcasses were tested on the midline or on the round. Each treatment was applied to a 103-cm2 area of the carcass surface, which was scored for visible contamination and analyzed for aerobic plate counts (APC) at 25°C and for total coliform counts (TCC). Average reductions in APC of 0.57 (Unit A) and 0.72 (Unit B) log CFU/cm2 and in TCC of 0.33 (Unit A) and 0.26 (Unit B) log CFU/cm2 were obtained by steam-vacuuming carcass surfaces which had no visible fecal contamination. Steam vacuuming and knife trimming effectively (P < 0.05) cleaned soiled carcass surfaces and reduced microbial counts. Knife trimming reduced APC and TCC by 1.38 and 1.61 log CFU/cm2 in the Unit A experiment and by 1.64 and 1.72 log CFU/cm2 in the Unit B experiment, respectively. Steam vacuuming carcass surfaces soiled with visible contamination reduced APC and TCC by 1.73 and 1.67 log CFU/cm2 (Unit-A) and by 2.03 and 2.13 log CFU/cm2 (Unit B), respectively. The results of this study suggest that both steam-vacuuming systems available at the time of the study were at least as effective as knife trimming in decontaminating beef carcasses with areas of visible contamination 2.54 cm in the greatest dimension.

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