Purpose: Monitor viability of Shiga toxin-producing Escherichia coli (STEC) and Listeria monocytogenes (Lm) in çiğ köfte during refrigerated storage.
Methods: Finely-ground beef (93:7% lean:fat) was separately inoculated (ca. 4.0 log CFU/g) with an eight-strain cocktail of STEC or a five-strain cocktail of Lm and then mixed with a traditional blend of bulgur wheat, salt, tomato sauce, diced tomatoes, green peppers, onion powder, fresh garlic, and various spices. Aliquots of buffered vinegar (BV; e(Lm)inateV) or distilled white vinegar (DV; 5% acidity) were added to the inoculated batter at levels of 0.0, 2.5, or 5.0% (vol/wt). The batter was hand-shaped into ca. 15 g balls and stored at 4° or 15°C for up to 3 days.
Results: When çiğ köfte was formulated with or without antimicrobials, pathogen numbers remained relatively unchanged after 3 days at 4°C. In contrast, when formulated without antimicrobials, STEC and Lm levels decreased by ca. 0.3 and 0.7 log CFU/g, respectively, after 3 days at 15°C. When formulated with BV, pathogens numbers decreased by ca. 0.2 log CFU/g during storage at 15°C. However, when DV was added to the formulation, reductions of 0.5 and 0.9 log CFU/g in STEC and Lm numbers, respectively, were observed. In contrast, when çiğ köfte was formulated without spices, DV, or BV pathogen levels increased by 0.2 to 0.6 log CFU/g when stored for 3 days at 15°C.
Significance: The çiğ köfte formulated herein did not support growth of STEC or Lm. Our data also highlight the antimicrobial contributions of the spices used to prepare çiğ köfte and the importance of proper handling/storage of the resulting product.