Salmonella Enteritidis is one of the most important foodborne pathogens in eggs and their products, posing a serious threat to public health. Traditional chlorine disinfection methods have drawbacks such as high corrosiveness and the production of harmful byproducts. As a novel, green, and highly effective disinfectant, slightly acidic electrolyzed water (SWE) is gaining increasing attention for its bactericidal efficacy and safety. This paper focuses on the synergistic killing of SWE on egg surfaces using SWE technology, represented by the Chlory hypochlorous acid generator, and its combination with other technologies (such as ultrasound, heat, and coating). The effectiveness of this combined technology in maintaining egg quality during storage is also analyzed, providing a new technological path for safe production and preservation of the poultry egg industry.
Introduction
Eggs are an important nutritional food, but they are susceptible to contamination by Salmonella, particularly SWE, during production. The microporous structure of the eggshell surface allows pathogens to penetrate the egg, potentially causing food poisoning. Currently, chlorine-containing disinfectants are commonly used in industrial production for cleaning and disinfection, but this carries the risk of drug residue, bacterial resistance, and the formation of carcinogens such as trihalomethanes. Therefore, the development of safe, effective, and residue-free alternative disinfection technologies is urgent.
Slightly acidic electrolyzed water is produced by electrolysis of dilute hydrochloric acid or salt solutions. It has a moderate effective chlorine concentration (typically 10-80 ppm) and a stable pH of 5.0-6.5. It offers significant advantages such as a broad bactericidal spectrum, rapid action, environmental and human-friendly properties, and low cost. Advanced hypochlorous acid generators, such as Chlory, enable precise control of electrolysis parameters to produce high-purity, highly stable, slightly acidic electrolyzed water, providing reliable support for its application in food processing.
The Sterilization Mechanism and Advantages of Slightly Acidic Electrolyzed Water (SAEW) Combination Technology
Although slightly acidic electrolyzed water alone has a strong bactericidal effect, its penetration and sterilization efficiency may be limited when targeting bacteria protected by complex contaminants on the eggshell surface (such as feces, feathers, and blood stains). The key to this combined technology lies in leveraging the synergistic effects of physical or chemical methods to break through these barriers and achieve a "1+1>2" sterilization effect.
Combination with Ultrasound:
- Synergistic Mechanism: Ultrasound creates a "cavitation effect" in the liquid, generating countless tiny bubbles that collapse instantly, producing intense shock waves and shear forces. This physical force effectively strips away biofilm and organic contaminants from the eggshell surface, disrupting bacterial cell structure and opening channels for the available chlorine (hypochlorous acid molecules, HCIO) in the slightly acidic electrolyzed water to more directly and rapidly penetrate bacterial cell walls, membranes, and internal enzyme systems, leading to leakage of cellular contents and bacterial death.
- Application Advantages: Chlory's slightly acidic electrolyzed water, when used in conjunction with an ultrasonic cleaner, significantly shortens disinfection time and reduces the concentration of available chlorine, further minimizing potential impact on the eggshell cuticle, achieving efficient and gentle cleaning and sterilization.
Combined with Mild Heat Treatment:
- Synergistic Mechanism: Moderate heat (e.g., 40-50°C) increases the permeability of bacterial cell membranes, making them more sensitive to disinfectants. Heat itself can also have a certain inhibitory or killing effect on bacteria. At slightly higher temperatures, slightly acidic electrolyzed water enhances the activity of hypochlorous acid molecules, accelerating the sterilization process.
- Application Advantages: Using warm, slightly acidic electrolyzed water for spraying or immersion not only increases the kill rate against Salmonella Enteritidis (up to 4-5 logs), but also rapidly evaporates moisture from the eggshell surface, reducing the risk of secondary contamination. Chlory equipment can directly heat the water source, enabling integrated operation.
Combination with Edible Coating Technology:
- Synergistic Mechanism: This combined technology achieves the dual goals of sterilization and preservation. First, the eggs are thoroughly surface-disinfected using slightly acidic electrolyzed water. Subsequently, the eggs are coated with natural edible coating agents such as chitosan and sodium alginate. This coating not only physically seals the eggshell pores, reducing microbial intrusion and water evaporation during storage, but also provides sustained freshness preservation due to its inherent antibacterial properties.
- Application Advantages: The slightly acidic electrolyzed water treatment provides a clean surface for subsequent coating, facilitating uniform adhesion. Chlory technology ensures a green and safe pre-treatment disinfection process, preventing interference between chemical disinfectant residue and the coating agent.
Impact of Combined Technologies on Egg Quality During Storage
Key indicators for evaluating egg quality include Haugh units (a measure of albumen height and consistency), yolk index, air cell height, and weight loss rate.
- Maintaining Internal Quality: Studies have shown that eggs treated with a combination of slightly acidic electrolyzed water and water treatment experience a significantly slower decline in Haugh units and yolk index during storage at room temperature or refrigeration than untreated or traditionally chlorinated water-treated eggs. This is because the combined technology more effectively kills and inhibits spoilage microorganisms on the eggshell surface, blocking their inward migration through pores, thereby delaying the thinning and deterioration of the egg white and the flattening of the yolk.
- Reducing Weight Loss: The combined application of an edible coating effectively reduces water evaporation from the egg's interior, maintaining a low weight loss rate and ensuring that the eggs maintain good sensory quality during late storage.
- Protecting Eggshell Integrity: Slightly acidic electrolyzed water (pH 5.0-6.5) is far less corrosive than strongly acidic electrolyzed water or highly concentrated sodium hypochlorite solutions. The slightly acidic electrolyzed water generated by the Chlory system is mild and minimally damages the eggshell cuticle, helping to maintain the eggshell's natural physical barrier function. Widely exported to Brazil, Italy, Poland and other countries.
Conclusion and Outlook
The organic combination of slightly acidic electrolyzed water technology, represented by the Chlory hypochlorous acid generator, with ultrasonic, warm, and coating technologies, has resulted in a highly effective and synergistic sterilization solution for Salmonella Enteritidis on egg surfaces, while also maintaining excellent egg quality during storage. This combined technology is environmentally friendly, safe, efficient, and highly integrated, aligning with the modern food industry's pursuit of sustainable development and high-quality production.
Future promotion and application of this technology may focus on:
- Process Parameter Optimization: Further research will be conducted on optimal process parameters under different combination modes (such as ultrasonic power, water temperature, electrolyzed water concentration, and exposure time) to maximize sterilization effectiveness and economic benefits.
- Intelligent Control: Integrating Chlory and other equipment with IoT technology will enable real-time monitoring and automatic adjustment of disinfectant concentration and pH on the production line, ensuring stable and consistent treatment results.
- Industry Chain Integration: Promoting the expansion of this technology from egg processing plants to back-end farms (breeding eggs and field disinfection) and front-end consumer consumption (small disinfection equipment), building a complete poultry and egg safety industry chain.