Rapid desiccation with heat in combination with water washing for reducing bacteria on beef carcass surfaces

Abstract

A series of experiments were conducted to determine the effectiveness of rapid desiccation with dry heat at one or two points in the slaughter process to reduce bacterial contamination on beef carcass surfaces. In the first set of experiments, several combinations of desiccation and water washes were examined. Beef surfaces were inoculated with bovine feces and water washed (IW; 125 psi, 15 s, 35°C); desiccated (400°C, 15 s) before inoculation and subjected to a water wash (D15400°CIW); inoculated, water washed and desiccated for 30 s (IWD30400°C); or desiccated, inoculated, water washed, and desiccated for 30 s (D15400°CIW D30400°C). Samples treated with D15400°CIWD30400°Cexhibited the lowest populations of APC, coliforms, andEscherichia coli. WhenE. coliO157:H7,Salmonella typhimurium,Listeria innocuaandClostridium sporogeneswere inoculated on to beef surfaces (3.30, 2.61, 3.97, and 3.63 log8CFU/cm2, respectively) and monitored following treatments with D15400°CIWD30400°C, none of the organisms were detected. To minimize surface discoloration, an additional set of experiments were conducted using less heat (300°C) for shorter times. When desiccation (300°C) was conducted for 10, 12, or 15 s prior to fecal contamination and followed by a water wash (D10,12,15300°CIW), it was demonstrated that none of the treatments were significantly different from the others for reducing APC from shortplates; however, the 10 s treatment was preferred for its shorter time. When desiccation for 10 s was combined with water washing and a second desiccation step (300°C) for 15, 20, or 25 s (D8300°CIWD15,20,25300°C), populations of APC, coliforms, andE. coliwere reduced to the greatest extent when the second desiccation step was applied for 25 s. This study is the first to report that water washing in combination with rapid desiccation with dry heat at one or two points in the slaughter process is more effective than water washing alone for reducing bacterial contamination on beef surfaces.