Underlying Mechanisms of Citronella Oil Vapor Generated by an Ultrasonic Humidifier in Inhibiting Pathogenic Bacteria and Extending the Shelf Life of Quail Eggs
Abstract
Ensuring the safety of quail eggs by preventing pathogenic bacteria is crucial for reducing outbreaks and ensuring food safety. This study developed a method for coating quail eggs, with the optimal coating conditions determined by vaporizing citronella oil nanoemulsion (CEO) at concentrations of 40, 80, and 120 µL/mL using an ultrasonic humidifier (UH) for 5, 10, and 15 min. The effectiveness of CEO vapor in preventing the growth of Salmonella Enteritidis, Escherichia coli, and Staphylococcus aureus was evaluated, along with its impact on shelf life at room temperature (30 ± 2 °C) for 10 days. The results showed that the optimal condition was CEO vapor at 80 µL/mL for 10 min. The CEO vapor formed a thin film on the eggshell, inhibiting biofilm formation and reducing bacterial counts from 6 log to around 1 to 3 log within 24 h. The morphology of bacteria on the treated eggs was abnormal, with pores on the cell walls. The aromatic ring bonds of citronella oil were detected on the eggshell surface, disrupting bacterial cells. The shelf life of coated eggs was extended to 7 days, with no detectable pathogens of Salmonella and E. coli, and the number of S. aureus was <2 log, in accordance with food safety standards, while control eggs showed contamination from day one. Therefore, the combination of vaporizing CEO at 80 μL/mL and using a UH for 10 min effectively ensured the safety of quail eggs.