The development of microflora on hot-boned and conventionally processed beef plate cuts was investigated from time of slaughter and/or fabrication throughout vacuum-packaged storage for 6 weeks at 0–1 C. Cuts from each processing treatment were analyzed immediately post-mortem and after 0.5, 1, 1.5, 2, 4, 7, 14, 21, 28 and 42 days of storage. Fabrication, packaging and chilling of beef plates were carefully controlled to minimize differences in chilling rates and contamination of hot and conventionally processed cuts. Microbial analyses included enumeration of mesophilic, psychrotrophic and total Enterobacteriaceae populations as well as taxonomic characterization of corresponding microbial isolates. Microbial counts of hot-boned cuts were generally higher than corresponding counts of conventionally processed cuts with significant differences (p<0.05) detected between mesophilic and psychrotrophic counts at most storage intervals between 14 and 42 days. Earlier predominance of organisms such as Lactobacillus spp. and Brochothrix thermosphacta on hot-boned vs. conventionally processed cuts was indicated by taxonomic determinations. Psychrotrophic Enterobacteriaceae, including Hafnia alvei and Yersinia enterocolitica-like organisms, were recovered in high numbers from a few samples after 28 and 42 days of storage regardless of processing technique. Differences in the development of microbial flora on hot and conventionally processed beef cuts could not be explained on the basis of differences in initial chill rates between treatments.
Proteomics as a Tool for the Characterization of Microbial Isolates and Complex Communities