Determination of changes in escherichia coli O157:H7 and salmonella numbers during the production and storage of kishk

Materials and Methods: Bulgur, yogurt, strained yogurt, and salt used in the preparation of kishk were procured from a local chain market. The prepared kishk mixture was artificially contaminated with E. coli O157:H7 and Salmonella, then subjected to fermentation at 35 oC for 48 hours, followed by drying at 53°C for four days. After the drying process, the kishk samples were stored at two different temperatures (4°C and 24°C) in sterile polyethylene bags for 36 days. Microbiological analyses (E. coli O157:H7, Salmonella, total mesophilic aerobic bacteria (TMAB), total psychrophilic aerobic bacteria (TPAB), lactic acid bacteria (LAB), coliforms, Staphylococcus-Micrococcus spp., yeasts, and molds), and chemical analyses (pH, titratable acidity, and dry matter content) were conducted at predetermined intervals. Results: During kishk production, Escherichia coli O157:H7 levels dropped below the detectable limit (<10 cfu/g) by the 24th hour of fermentation, while Salmonella was found to be completely eliminated based on presence/absence analysis. By the 48th hour of fermentation, E. coli O157:H7 was also no longer detectable by the presence/absence test. The total mesophilic aerobic bacteria (TMAB) count showed a decreasing trend throughout production and storage, particularly at 4°C. Lactic acid bacteria (LAB) and total psychrophilic aerobic bacteria (TPAB) increased significantly during fermentation but demonstrated a tendency to decline during storage at 24°C (P < 0.05). Coliforms, yeasts, and molds were found to be below detectable limits following the drying stage and throughout the storage period. Micrococcus-Staphylococcus spp. were not detected in any sample during the entire production and storage phases. Over the course of storage, especially in samples stored at 24°C, a marked decrease in pH was observed, accompanied by an increase in acidity levels and a slight rise in dry matter content. Conclusion: As a result of this study, kishk production was found to have a significant inhibitory effect (6-9 logs) on the viability of Escherichia coli O157:H7 and Salmonella. In this context, kishk may be considered a microbiologically safe product with respect to these pathogens. However, to validate this assumption, further studies investigating the survival of wild-type strains are necessary. Keywords: E. coli O157:H7, kishk, Salmonella, storage, survival ability.