Quantification of loosely associated and tightly associated bacteria on broiler carcass skin using swabbing, stomaching, and grinding methods

Abstract

This research was conducted to quantify bacterial populations after swabbing or stomaching, followed by grinding the swabbed or stomached broiler skins. For each of 3 replications, 3 eviscerated broilers were randomly taken from a processing line in a local broiler processing plant. Ten swabs and 10 stomachs per bird were conducted on the left- and the right-side skins (10 × 7 cm), respectively, which were then finally ground. Results indicated that mesophilic aerobic bacteria (MAB) in the first swabbed sample were significantly lower than those in the first stomached sample (P < 0.05), with no difference seen for the remaining sampling times (P > 0.05). During 10 swabbings followed by final grinding, 8, 9, and 83% of MAB were detected after the first swabbing, after the second through 10th swabbings, and after final grinding of the skin, respectively. During 10 stomachings followed by the final grinding, 17, 18, and 65% of MAB were detected after the first stomaching, after the second through 10th stomachings, and after final grinding of the skin, respectively. Escherichia coli (E. coli) and coliforms were significantly higher in the first stomaching than those in the first swabbing (P < 0.05), with no difference seen between the 2 sampling methods for the rest sampling times (P > 0.05). Populations of E. coli and coliforms decreased step-wisely from the highest after grinding to the intermediate after first and second sampling, and to the least after 10th sampling (P < 0.05), regardless of swabbing or grinding. In this study, less than 35% of MAB seemed loosely associated in the skin of eviscerated broiler, whereas more than 65% of MAB looked tightly associated, which were not recovered by stomaching or swabbing even 10 times but were recovered by grinding the skin.