Effects of countercurrent scalding and postscald spray on the bacteriologic profile of raw chicken carcasses

In June and September 1988, the USDA Food Safety and Inspection Service sampled raw chicken carcasses at a federally inspected slaughter establishment in Puerto Rico to determine the effects of changing the scalding equipment on bacterial contents of raw poultry products. The scalding equipment was changed to a countercurrent configuration, with a postscald hot-water rinse cabinet that sprayed carcasses as they exited the scalder. Analysis of 250 carcass-rinse samples collected at preevisceration, prechill, and postchill sites over 7 days indicated that carcasses had mean aerobe plate counts of log(10)3.73 before evisceration, 3.18 before chilling, and 2.87 after chilling; Enterobacteriaceae counts of log(10)2.70 before evisceration, 2.25 before chilling, and 1.56 after chilling; and Escherichia coli counts of log(10)2.09 before evisceration, 1.61 before chilling, and 0.89 after chilling. Salmonellae were found on 24% of the carcasses before evisceration, on 28% before chilling, and on 49% after chilling. Although bacterial count reductions were significant at all 3 sites, the proportion of carcasses contaminated with salmonellae in this study was higher at the postchill than prechill site (49 vs 28%). This no doubt was caused by cross-contamination in the chiller. These percentages indicated that although simple scalder changes contributed substantially to the improvement of the bacterial quality of chicken carcasses, additional interventions in the chilling process (such as chlorination of chill water) are important to control cross-contamination and to preserve the positive effects obtained by the scalder changes.