Antimicrobial Activity of Thymol and Thymol-Nanoemulsion Against Three Food-Borne Pathogens Inoculated in a Sausage Model

In the present study, the antimicrobial efficiency of thymol and thymol-nanoemulsion (NE) was investigated against S . aureus , E. coli , and C. perfringens on a sausage product during 4 weeks. The droplets size of the thymol-NE was 86.39 nm with the zeta potential of −0.86 mV. The MIC and MBC values for thymol were approximately twice that of NE, indicating that NE was more effective in inhibiting the growth of three tested bacteria. According to agar well diffusion test results, the antimicrobial activity of thymol and the NE was not different against three tested bacteria. In inoculated sausages with E. coli , C. perfringens , and S. aureus at 10 5.5 log CFU/g, the control had the highest bacterial counts, followed by 120 mg/kg nitrite treated samples, both of which had an increasing trend over time. In contrast, the growth trend of all three bacteria, in the samples treated with thymol (600 mg/kg), NE (containing 600 mg/kg thymol), thymol (600 mg/kg) + nitrite (60 mg/kg), and NE (containing 600 mg/kg thymol) + nitrite (60 mg/kg) decreased significantly (5.68–6.33 log CFU/g reduction in comparison with control), with no significant difference among them against each bacterium. The color quality of NE + nitrite and thymol + nitrite was quite similar to 120 mg/kg nitrite-containing samples. The bacteria growth followed a first-order kinetic. The results showed the great potential of thymol and its NE for being used as an antimicrobial agent in the meat products, and NE + nitrite and thymol + nitrite can be a good choice to maintain the microbial and color quality of the sausage products.