Chang V P, Mills E W, Cutter C N
Department of Food Science, 111 Borland Laboratory, Agricultural and Sciences Building, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
J Food Prot. 2003 Jun;66(6):1019-24. doi: 10.4315/0362-028x-66.6.1019.
In addition to reducing the temperature of pork carcasses immediately after slaughter and before fabrication, blast chilling (snap chill) or conventional chilling can reduce bacterial populations associated with fresh meats. However, there is little information on bacteria survival resulting from the freeze or chill injury of meat products. In this study, porcine fecal slurries with and without pathogens (Listeria monocytogenes, Salmonella Typhimurium, and Campylobacter coli) were inoculated onto skin-on and skin-off pork surfaces and subjected to industry-specific blast or conventional chilling conditions. A thin agar layer method was used for the recovery of freeze- or chill-injured cells. Test results indicated that there were no statistically significant (P > 0.05) differences between blast and conventional chilling treatments with respect to the reduction of high and low inoculation levels of mesophilic aerobic bacteria, total coliforms, or Escherichia coli on either skin-on or skin-off surfaces. Chilling treatments did not differ significantly (P > 0.05) with respect to their ability to reduce low (3 log10 CFU/cm2) levels of L. monocytogenes and Salmonella Typhimurium. However, C. coli was reduced to undetectable levels, even after enrichment, on pork surfaces inoculated with low levels (3 log10 CFU/cm2) and subjected to blast chilling. Blast and conventional chilling treatments were more effective against all pathogenic bacterial populations when pork surfaces where inoculated at high levels (5 log10 CFU/cm2). The effects of chilling techniques on microbial populations could provide pork processors with an additional intervention for pork slaughter or information to modify and/or improve the chilling process. The information obtained from this study has the potential to serve as a means of producing a microbiologically safer product.
除了在屠宰后和分割前立即降低猪胴体温度外，快速冷却（速冻）或传统冷却还可以减少与鲜肉相关的细菌数量。然而，关于肉类产品因冷冻或冷却损伤导致的细菌存活情况的信息很少。在本研究中，将含有和不含病原体（单核细胞增生李斯特菌、鼠伤寒沙门氏菌和空肠弯曲菌）的猪粪便浆液接种到带皮和去皮猪肉表面，并使其经受特定行业的快速冷却或传统冷却条件。采用薄琼脂层法来复苏冷冻或冷却损伤的细胞。测试结果表明，在带皮或去皮表面上，对于嗜温需氧菌、总大肠菌群或大肠杆菌的高接种水平和低接种水平的减少，快速冷却和传统冷却处理之间没有统计学上的显著差异（P>0.05）。就降低单核细胞增生李斯特菌和鼠伤寒沙门氏菌的低水平（3 log10 CFU/cm2）而言，冷却处理的能力没有显著差异（P>0.05）。然而，在接种了低水平（3 log10 CFU/cm2）并进行快速冷却的猪肉表面上，即使经过富集，空肠弯曲菌也被降低到检测不到的水平。当猪肉表面接种高水平（5 log10 CFU/cm2）时，快速冷却和传统冷却处理对所有病原菌种群的效果更好。冷却技术对微生物种群的影响可为猪肉加工商提供猪肉屠宰的额外干预措施，或为修改和/或改进冷却过程提供信息。从本研究中获得的信息有可能成为生产微生物学上更安全产品的一种手段。
