Time-temperature profiles in the food supply chain of the Austrian Armed Forces and implications for microbiological food safety

We examined the temperature regimen in a Cook-and-chill chain (Hot-portioning - rapid chilling - cold storage - reheating and holding hot until distribution) in a mass catering setting. Temperature measurement was done by embedded thermologgers. In the nine product types under study, rapid chilling effectuated a drop in the core temperature to <10 degrees C within 90 min. During cold storage, a temperature of <4 degrees C was maintained and during reheating, temperature peaked at >75 degrees C. In the ready-to-eat products, aerobic mesophilic counts were <100 to 400 cfu/g. In two food items (beef goulash and chicken cut into strips), we studied the effect of low hot-holding temperatures for 15 min and 3.5 h prior to serving. In the native food samples, total aerobic counts were <100 cfu/g before and after holding at 40, 50, 60 or 70 degrees C. As regards food items that had been contaminated with a mixed culture of E. coli, Salmonella typhimurium, Listeria spp., Pseudomonas aeruginosa and Staph. aureus (each 5.0-5.5 log cfu/g), reductions (>= 0.5 log) of bacterial numbers were observed in beef goulash at temperatures of 50 degrees C and above, whereas for the chicken products, bacterial reductions were observed at 70 degrees C only. In practice, the recommended minimum hot-holding temperatures have to be based on the most sensible food items.