Change of Campylobacter, Escherichia coli and Salmonella counts in packaged broiler breast meat stored under modified atmosphere and vacuum conditions at 4 and 10 °C based on cultural and molecular biological quantification
Anja Beterams, T. Tolksdorf, Annett Martin, Kerstin Stingl, Niels Bandick, Felix Reich
Abstract
Poultry on the European market is offered primarily as fresh meat and is usually sold at the retail level packed under either a modified atmosphere (MAP) or vacuum. Packaging is meant to retain product quality during retail offering and influences microbiological changes during storage. The focus of this study was to determine the influence of routinely used broiler meat packaging technologies on the change of Campylobacter, Salmonella and Escherichia coli counts on chicken breast meat. Chicken breast meat was inoculated with Campylobacter (5 log10 cfu/g), Salmonella and E. coli (each at 4 log10 cfu/g), packaged under MAP or vacuum conditions and stored at 4 and 10 °C over a period of 13 days. Cultural microbiological analysis was used together with quantitative viability real time PCR (v-qPCR) to assess the development of inoculated bacteria as well as the general hygiene and spoilage microbiota. The results showed a reduction of thermophilic Campylobacter spp. of about 2 log10 cfu at the end of storage for MAP meat as compared to vacuum packed meat. However, this reduction was not observed by v-qPCR, where viable Campylobacter spp. counts remained almost at inoculation level. No change in cfu was observed for either Salmonella or E. coli. The results indicate that examination by culturing alone can lead to an underestimation of the Campylobacter spp. load on fresh broiler meat. Quantitative molecular biological analysis with live/dead differentiation is applicable for overcoming the limitations of culturing methods and therefore requires further verification through additional studies under retail conditions on different matrices.