Gelatin-based rechargeable antibacterial hydrogel paint coating for reducing cross-contamination and biofilm formation on stainless steel

Microbial cross-contamination on food contact surfaces is a significant challenge. Due to both technical and regulatory requirements, many of the current antimicrobial compositions and coatings are difficult to apply on food contact surfaces. To address this challenge, we have developed a food-grade hydrogel antimicrobial paint coating based on a combination of gelatin and tannic acid. This coating approach addresses some of the key limitations of conventional hydrogel coatings and provides a stable antimicrobial coating on stainless steel (SS) surfaces. Based on the rapid binding of chlorine to the hydrogel paint coating, the results of this study demonstrate total chlorine content (1.25 ± 0.05 μmol/cm2) on the SS surface and improved stability of bound chlorine in the presence of high organic content, upon extended storage of the coated surfaces, and exposure to UV-A light. Furthermore, the chlorine content on the SS surface could be repeatedly recharged to the same level as the initial concentration of bound chlorine on the SS surface. Bound chlorine on the coated surface inactivated over 5 log of inoculated bacteria per cm2 of both Listeria innocua and E. coli O157:H7 in 5 min even in the presence of the high organic content. In addition, chlorine bounded to coated surface prevented biofouling of SS surfaces upon extended exposure of the SS surface to L. innocua and E. coli O157:H7. The antimicrobial surface was also effective in significantly reducing the cross-contamination of SS surface upon contact with contaminated fresh produce. In summary, the antimicrobial hydrogel paint coating approach developed in this study has significant potential to improve food safety and reduce the risk of cross-contamination.