Complex Internal Microstructure of Feather Follicles on Chicken Skin Promotes the Bacterial Cross-Contamination of Carcasses During the Slaughtering Process.

Xibin Zhang,Peng Li,Yanwei Mao,Zixin Peng,Xin Luo,Ru Shen,Xiuguo Diao,Rui Tao,Yuzhong Zhao,Longhai Liu

doi:10.3389/fmicb.2020.571913

Abstract

Chicken skin is considered the most susceptible to bacterial contamination during slaughter. It is rich in bushy feather follicles with complex internal structures that can absorb bacteria via cross-contamination during slaughter. Until now, the microstructural changes and local bacterial composition of feather follicles during slaughter have not been thoroughly investigated. This study used hematoxylin-eosin (HE) staining of the tissue paraffin section to investigate the structure of the feather follicles on chicken skin. In addition, the biopsy sampling method was employed for the high-throughput sequencing of 16S RNA genes to study the composition and source of bacterial contamination during slaughter. The results show that the feather follicles on chicken skin form a closed cavity structure during the slaughtering process. The volume of the irregular follicle cavity was about Ø: 200 μm × D: 1040 μm, which provides a place for the bacteria to absorb and resist the cleaning and disinfection during the slaughtering process. The composition of bacteria in the feather follicle was mainly Acinetobacter (37%), Psychrobacter (8%), Macrococcus (5%), and Comamonas (2%). The heat map obtained via the species abundance analysis of the feather follicle samples as well as the slaughter environment samples suggests that the gastrointestinal feces contaminated the feather follicles on the chicken skin mainly during the evisceration, defeathering, and chilling processes, and the last-stage chilling water also caused severe cross-contamination to the feather follicles during the chilling process.

Highlights

Chicken has become a widely consumed meat worldwide due to its rich nutrition, abundant supply, and low cost (OECD, 2013)
Mini punch is a tissue transplantation and biopsy sampling method widely used during medical skin surgery (Huang et al, 2012; Hirobe and Enami, 2018; Fofanov et al, 2019), and it can be combined with other analytical methods to realize the detection and analysis of trace samples
The evisceration process significantly increased the total viable count (TVC) of the carcass rinse (P < 0.05) from 4.56 to 5.19 CFU/ml while, interestingly, the COLI was not significantly changed (P > 0.05), which might show that the process of the defeathering step occurred in the intestinal content contamination

Summary

Introduction

Chicken has become a widely consumed meat worldwide due to its rich nutrition, abundant supply, and low cost (OECD, 2013). It is generally believed that the complex structure of chicken skin tissue makes it more susceptible to bacterial contamination because it is difficult to clean and reduce bacteria during slaughter (Berndtson et al, 1992; Yang et al, 2001; Cason et al, 2004; Jang et al, 2007; Latt et al, 2018). Many studies have documented the location of contamination bacteria on the surface microstructure of chicken skin as well as bacterial cross-contamination during slaughter (Cason et al, 2004; Chantarapanont et al, 2004; Jang et al, 2007; Latt et al, 2018). Mini punch is a tissue transplantation and biopsy sampling method widely used during medical skin surgery (Huang et al, 2012; Hirobe and Enami, 2018; Fofanov et al, 2019), and it can be combined with other analytical methods to realize the detection and analysis of trace samples

Methods

Results

Conclusion