Investigation of microbiological counts on carcasses in U.S. lamb slaughter plants and development of a model HACCP plan for lamb feeding, transportation, receiving and slaughtering/dressing

Abstract

Carcass microbiological counts (2,159 Total Coliform Counts and 2,146 Aerobic Plate Counts) were taken at six U.S. lamb slaughter facilities during Fall (September to November) and Spring (April to June) seasons. Microbiological sampling was at four carcass sites; the leg, loin, breast and axillary area of shoulder. Microbiological samples were obtained at four plant stations, Post-depelting; Pre-first wash (Station 1), Post-first wash; Pre-evisceration (Station 2), Post-evisceration; Pre-final wash (Station 3), Post-final wash; Pre-cooler (Station 4). Station and the Season by Station interaction had highly significant (P<.01) effects on Total Coliform Counts. Total Coliform Counts increased significantly (P<.01) between Post-first wash; Pre-evisceration (1.52 log10 CFU/20 cm2) and (4.34 log10 CFU/20 cm2) Post-evisceration; Pre-final wash. Seasonal effects were significant (P<.01) for Total Coliform Counts at Post-depelting; Pre-first wash and nonsignificant at all other plant stations. Significant fixed effects for Aerobic Plate Counts included Station, Carcass Site and the Station x Carcass Site interaction. Aerobic Plate Counts increased (P<.01) between Station 1 (Post-depelting; Pre-first wash) and Station 2 (Post-first wash; Pre-evisceration) and again between Station 2 and Station 3 (Post-evisceration; Pre-final wash). The lowest Aerobic Plate Counts were at the loin carcass site; Aerobic Plate Counts there were lower (P<.01) than those from the leg, breast and axillary area of the shoulder at Station 2. Initially low Aerobic Plate Counts on the loin carcass site reached levels comparable to those on the leg, breast and axillary carcass sites between Station 1 and Station 2. Correlation coefficients between Total Coliform Counts, Aerobic Plate Counts and Chain Speeds (carcasses processed per hour) were calculated. There was a strong correlation (.863) between Total Coliform Counts and Chain Speed, but no apparent relationship between Aerobic Plate Counts and Chain Speed (-.058). A HACCP-based plan was developed specifically for sheep slaughtering and dressing. Six Control Points (CPs) and three Critical Control Points (CCPs) were identified in the model HACCP plan. Critical Control Points for the model HACCP plan include final washing and/or bactericidal spraying (CCP-1), "Zero Tolerance" Inspecting (CCP-2), and Carcass Chilling (CCP-3). Critical Control Points were identified as areas along the process chain where measurable and effective interventions could be put in place with an expected reasonable degree of success in controlling what are primarily microbiological hazards.