Foodborne illnesses caused by Salmonella are a significant global public health concern, with eggs serving as the major transmission route (Whiley and Ross, 2015; Galiş et al., 2013). Among the various serotypes, Salmonella Typhimurium is responsible for most reported cases, particularly in the United States and Europe, where infections exceed one million annually (Chousalkar et al., 2018; Helms et al., 2005; Dar et al., 2017). A notable outbreak in the U.S. in 2010 resulted in over 1500 confirmed cases and the recall of more than 500 million eggs (Laestadius et al., 2012). Salmonella contamination can occur through transovarial transmission from infected hens or through external exposure during processing and handling (Pande et al., 2016; Cox et al., 2000). This risk is particularly concerning in populations where raw or undercooked eggs are frequently consumed, such as in Korea, highlighting the need for more effective control measures (Oh et al., 2023; Eun et al., 2024).

Refrigeration remains the primary strategy for limiting Salmonella contamination, with regulatory standards in the U.S. and Korea requiring egg storage at or below 7 °C and 5 °C, respectively (Li et al., 2024; Park et al., 2015). However, in regions with limited cold-chain infrastructure, refrigeration alone is insufficient to ensure microbial safety (Mercier et al., 2017). Egg coatings have been explored as a complementary approach to establish a physical barrier against bacterial penetration while preserving egg quality (Pires et al., 2020; Eddin et al., 2019). Various antimicrobial coatings, including those incorporating chitosan, nanoparticles, and pullulan, have shown potential for reducing bacterial contamination; however, high production costs have hindered their widespread application (Kim et al., 2009; Wang et al., 2021; Morsy et al., 2015).

Bacteriophages (phages), viruses that specifically infect and lyse bacteria, have emerged as promising alternatives to conventional antimicrobial methods (Wittebole et al., 2013; Golkar et al., 2014). Unlike antibiotics and chemical disinfectants, phages offer high specificity and minimal environmental impact and have been classified as Generally Recognized as Safe (GRAS) by the U.S. Food and Drug Administration (FDA) (Bisen et al., 2024; Soni and Nannapaneni, 2010). Since the discovery of the lytic Salmonella phage Felix-O1, phages have been explored as tools to enhance food safety, including the control of Salmonella on eggshells (Whichard et al., 2003; Cao et al., 2022; Braz et al., 2025a). However, the eggshell is a challenging substrate where environmental stresses, especially rapid desiccation, can severely limit phage viability and efficacy (Azari et al., 2023). To overcome these barriers, various delivery strategies such as spraying, microencapsulation, and biopolymer coatings have been investigated (Hernández-Arteaga et al., 2025; Wang et al., 2024; Gvaladze et al., 2024). These efforts highlight the need for robust, long-lasting phage formulations optimized for eggshell application to improve retention and enhance antimicrobial efficacy under real-world conditions (Pires et al., 2022).

This study aimed to develop and evaluate a phage emulsion coating to enhance the safety of eggs, to address the challenges on eggshell surfaces. A newly isolated T4-like lytic phage, pSe_SNUABM_01, exhibited strong lytic activity against Salmonella Typhimurium. A mineral oil-based emulsion was optimized for phage stability and antibacterial efficacy (Waimaloengora-Ek et al., 2009). The antibacterial effectiveness of the phage emulsion coating was assessed by evaluating its ability to prevent Salmonella penetration, reduce bacterial colonization, and improve microbiological safety. This approach represents a viable and sustainable strategy for reducing Salmonella-associated foodborne illnesses, particularly in regions with limited refrigeration.