This study aims to investigate the effect of keeping time in bain-marie and different cooling speeds on the microbiological quality of meatballs served in catering systems after contamination with Escherichia coli. For this purpose, the meatball mixture prepared was divided into two equal portions, Group A and B, and then subjected to frying, with Group B being inoculated with E. coli. After inoculation, the prepared meatballs were held at 70°C for 2 hours and cooled at different rates. The total mesophilic aerobic bacteria (TMAB) and yeast-mold counts in the meatball mixture, initially measured at levels of 5.59 log10 cfu/g and 7.91 log10 cfu/g respectively, decreased to levels of 2.92 log10 cfu/g and 3.58 log10 cfu/g after frying. After 2 hours in the bain-marie, the TMAB and yeast-mold levels in Group A meatballs were observed to be 2.42 log10 cfu/g and 2.30 log10 cfu/g, respectively. After inoculation, the TMAB, TAPB, E. coli, and yeast-mold levels in Group B meatball samples decreased continuously as a function of heating and cooling time. While the initial E. coli level was 8.13 log10 cfu/g, it decreased to 5.49 log10 cfu/g after 2 hours of heating and further decreased to 3.73 log10 cfu/g when the sample temperature reached 4°C. It was found that the microbial quality of Group B meatball samples cooled at +4°C was better than those cooled at room temperature. Meatball groups containing E. coli were found to have a higher pH value compared to those without E. coli and the pH increased further when both groups were left to cool at room temperature. The results suggest that applying rapid chilling after serving meatballs in catering systems positively affects the microbial quality of the product.
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