The use of ozone and ultrasonication technologies on the disinfection of egg surface

Effectiveness of ozone (O) (1O3; 33.6 g/m3, 5 min and 2O3; 101.0 g/m3, 15 min), ultrasonication (US) (1US; 35 kHz, 1200 W, 3 min and 2US; 35 kHz, 1200 W, 6 min) and their combined applications (3US+3O3; 1200 W, 35 kHz, 2 min+20.2 g/m3, 3 min and 3O3+3US; 20.2 g/m3, 3 min+1200 W, 35 kHz, 2 min), on the inactivation of natural microflora and pathogen bacteria (Escherichia coli O157:H7, Salmonella Enteritidis, Listeria monocytogenes) contaminated on egg shell surface and imaging of both egg surface and bacteria by scanning electron microscobe (SEM) were prompted in the study. Moreover, effect of these applications on the sensory and the quality characteristics (weight, specific gravity, color, shape index, Haugh unit, albumen index, yolk index, pH, egg surface mineral analysis) off eggs were also examined. It was found that while ozone applications (5 and 15 min) provided a significant decrease in the initial numbers of L. monocytogenes (2.48 and 2.83 logs cfu/mL), S. Enteritidis (2.63 and 3.20 logs cfu/mL), E. coli O157:H7 (5.9 and 6.7 logs cfu/mL) and total Enterobacteriaceae (2.34 and 5.42 logs cfu/mL); total mold and yeast count was completely inhibited. Moreover, no adverse effect was observed on the sensory and the quality characteristics of the eggs. Compare to ozone, US applications (3 and 6 min) resulted in less reduction on the initial counts of microbial load (L. monocytogenes 0.64 ve 0.61 log cfu/mL, S. Enteritidis 1.08 ve 1.13 log cfu/mL, E. coli O157:H7 0.02 ve 0.38 log cfu/mL) causing an increase in weight and specific gravity of the quality characteristics and a decrease on eggshell strength and cracking in eggshell with no significant change in the sensory characteristics of the eggs. Combinations of these technologies -with ozon applied before US- were more effective on microbial inactivation, but undesired changes on quality attributes were observed in both 3US+3O3 and 3O3+3US combinations. While structural deformations and distruption of cells were observed depending on the application doses by SEM; cracking and corrosion on eggshell were detected after US applications (1US, 2US, 3US+3O3, 3O3+3US). Therefore, it is suggested to use ozone technology to ensure egg safety and quality.