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The spoilage of meat products (N>5×10 6 CFU g -1 ) can be delayed by cooling and low-temperature storage and transport. The highest extent of interruption in the cold chain occurs at the time of delivering the meat product to the individual's home after purchasing it. Consumer behaviour and the ambient temperature largely infl uence the shelf life of products. In our research, we examined the buying habits of customers in Hungary. Based on these results, we carried out the cold chain interruption of vacuum-packed sliced ham (1, 2, 3 h) under laboratory conditions, at temperatures of 15, 25, and 35 °C. The microbial count was determined by a quick method based on redox-potential measurement in two-three days until the products were deteriorated. Our experiments resulted in the expected outcomes; however, we concluded that even average customer habits (1 h cold chain interruption) at higher temperature periods (T>20 °C) decrease the shelf life of ham by 6 days. We set up a mathematical model through which the changes of microbial counts can be determined as a function of product temperature changes, the period of delivery, and the subsequent period of cold storage. R 2 =0.9 correlation was given between predicted and measured microbial counts (logN).

The incidence of outbreaks of foodborne listeriosis has indicated the need for a reliable and rapid detection of the microbe in different foodstuffs. A method combining redox potential measurement and real-time polymerase chain reaction (PCR) was developed to detect Listeria monocytogenes in artificially contaminated raw milk and soft cheese. Food samples of 25 g or 25 ml were homogenised in 225 ml of Listeria Enrichment Broth (LEB) with Oxford supplement, and the redox potential measurement technique was applied. For Listeria species the measuring time was maximum 34 h. The absence of L. monocytogenes could reliably be proven by the redox potential measurement method, but Listeria innocua and Bacillus subtilis could not be differentiated from L. monocytogenes on the basis of the redox curves. The presence of L. monocytogenes had to be confirmed by real-time PCR. The combination of these two methods proved to detect < 10 cfu/g of L. monocytogenes in a cost-and time-effective manner. This method can potentially be used as an alternative to the standard nutrient method for the rapid detection of L. monocytogenes in food.

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