Determination of the effects of ultrasonication and carvacrol against E. Coli ATCC25922 in a meat model system and investigation of their interaction with food ingredients

In this study, ultrasonication as a non-thermal preservation method and carvacrol, a natural plant-derived antimicrobial, were used to evaluate the inactivation effects against E. coli ATCC 25922 in a meat model food system. In this context, the effective doses, sonication time and their synergistic effects were investigated. For this purpose, model food samples contaminated with E. coli ATCC 25922 at the level of ~107cfu/ml were sonicated with 600 ppm, 900 ppm, 1200 ppm antimicrobial added and the sample without antimicrobial added in an ultrasonication device (20kHz, 200W) with 90% amplitude and 0.5 s run-stop cycle (Cycle: 5) settings for 22 minutes. Alive microorganisms were counted at 0, 2, 4, 6, 8, 10, 14, 18, 22 minutes. Meat model foods were prepared in TSB with protein and fat percentages of 15%-5% (Group A), 10%-10% (Group B), 5%-15% (Group C), respectively. In Group A, for0 ppm and 600 ppm at the 22nd minute, 5.15±0.11 log and 5.45±0.20 log reductions were observed, and for 900 ppm and 1200 ppm at the 18th minute, 4.98±0.23 and 4.99±0.23 log reduction were observed respectively. In Group B, for 0 ppm and 600 ppm, 5.4±0.06 log and 5.55±0.01 log at 22nd min, and for 900 ppm and 1200 ppm5.59±0.28 log and 5.25±0.33 log reductions at 18th min were observed respectively. In Group C, there were 5.47±0.19 log, 5.5±0.06 log, 5.55±0.35 log and 5.21±0.34 log reductions at 18th min, respectively. When we compared the samples without antimicrobial, it was concluded that protein content decreased the bactericidal effect of ultrasonication more than fat content. It was observed that as the fat concentration increased, the antimicrobial bioactivity decreased. The inactivation of E. coli ATCC 25922 in the model food was observed to fit the first order kinetic model and the kinetic model equations and D values were determined for each condition by linear regression analysis. As a result of univariate statistical analysis, the effect of model food formulation (protein/fat) on D value was found to be statistically effective (p<0.05), while other factors (antimicrobial dose) were found to be ineffective.