Microbial Decontamination and Weight of Carcass Beef as Affected by Automated Washing Pressure and Length of Time of Spray1

Abstract

Carcasses were obtained from 56 heifers that were fed a corn-corn silage diet to determine the effects of automated washing water spray pressures (SP) of 2412 kilopascal (kPa) or 4134 kPa and chain speeds (CS) of 3.9, 5.9 or 7.9 m/min on microflora and weight changes of carcass beef. Carcass beef sides were weighed before washing, 5 min after washing and 20 h after washing and storage at 0°C. Enterobacteriaceae and aerobic counts of forequarters and hindquarters were determined before and 20 h after washing. Carcass sides shrank 1.52 kg after 20 h of storage. This shrinkage was similar among all treatment groups. Washing reduced Enterobacteriaceae counts 1.57 log10 colony forming units (CFU)/200 cm2 and counts of aerobic bacteria 0.87 log10 CFU/200 cm2. All combinations of SP and CS were similar in effectiveness of reducing Enterobacteriaceae counts. However, the low SP tended (P<0.102) to be more effective in reducing aerobic counts. Forequarters possessed greater (P<0.051) aerobic counts (5.44 vs 5.29 log10 CFU/200 cm2) than hindquarters, but washing eliminated this differential. Automated carcass washing reduced bacterial counts of carcass beef, but within treatments applied, SP and CS had no effect on variation in carcass weight or variation in reduction of microflora. Research indicated that automated carcass washing was a useful procedure for reducing bacterial counts on carcass beef without affecting carcass weights.