Inhibitory effects of nisin combined with plant-derived antimicrobials on pathogenic bacteria and the interaction with complex food systems

Abstract

This study aimed to evaluate the synergistic effects of nisin combined with cinnamaldehyde (Nis+Cin) and nisin combined with carvacrol (Nis+Car) on food-borne bacteria. The minimum inhibitory concentrations for Nis, Cin and Car ranged from 2,500 to 10,000 IU/mL, 0.78-6.25 mg/mL and 0.78-3.13 mg/mL, respectively. Nis+Cin displayed a total synergism against all test bacteria, showing a marked release of bacterial intracellular constituents. In a food model, high protein concentration, low starch and oil concentration as well as low pH, positively influenced the antimicrobial activity. Moreover, in sandwich spread, Nis+Cin enhanced the inhibition of S.Typhimurium at the greatest level by reducing cell numbers by more than 4 log CFU/g from 6 days of storage. These results suggest that the dose used for each antimicrobial compound can be minimized by combination, thereby decreasing the possibility of antimicrobial resistance and also reducing food processing costs.