Synergistic effect of X-ray irradiation and sodium hypochlorite against Salmonella enterica serovar Typhimurium biofilms on quail eggshells

The present study investigated the synergistic bactericidal effects of combined X-ray irradiation (0.5, 1.0, 1.5, and 2.0 kGy) and sodium hypochlorite (NaOCl) (50, 100, 150, 200, and 300 ppm) treatment on the reduction of S. enterica serovar Typhimurium ATCC 14028 biofilms on quail eggshells. Additionally, the color change of the quail eggshells was measured by hunter color "L" (lightness), "a" (red/green), "b" (yellow/blue), and "ΔE" (total color difference). Additionally, the puncture force was tested to evaluate eggshell thickness after the combined treatments. The highest biofilm reduction values were observed as 4.6 log CFU/egg after X-ray (2.0 kGy) and NaOCl (300 ppm) treatment. Moreover, the synergistic reduction in values after combined treatment was evaluated, and the highest biofilm reduction value was 4.3 log CFU/egg by 2.0 kGy X-ray/50 ppm NaOCl (1.47 log higher than the sum of reduction values of the individual treatments). The color of the quail eggshell and puncture force were not significantly changed by combined treatments (p > 0.05 at both cases). Consequently, 2.0 kGy X-ray/50 ppm NaOCl was considered optimal for combination treatment for eliminating S. enterica ser. Typhimurium biofilms on eggshell without any color or thickness changes. Furthermore, combination treatment could be useful for improving microbiological safety in the quail egg industry.