Development of a food grade sanitizer delivery system with chlorine loaded gelatin microgels for enhanced binding and inactivation of biofilms

Sanitation of water, food, and food contact surfaces is essential for the safety of food supply. Lack of stability of sanitizers in the presence of organic content and lack of targeted binding of sanitizers to biofilms can reduce effectiveness of sanitizers and increase the risk of contamination of food. Therefore, this study evaluated the development, characterization, and application of gelatin microgel based chlorine delivery system for improving both stability of chlorine based sanitizer and targeted binding of sanitizer to biofilms. The results illustrate that cross-linked gelatin microgels rapidly bind chlorine to form a halamine bond. The total chlorine loading was 5.05% per gram of gelatin microgels. Chlorine bound to gelatin microgels was stable in the presence of high organic content up to 2,000 mg/L and in a powder form for 5 weeks under refrigerated conditions. Gelatin microgel particles significantly improve the inactivation of bacteria in the presence of organic content compared to equivalent concentration of free chlorine. Gelatin microgel particles had affinity to bind biofilms with 26.5% and 22.9% to the L. innocua and E. coli O157:H7 biofilms, respectively. In bacterial biofilm models, more than 6 log CFU/cm2 of L. innocua and E. coli O157:H7 were inactivated within 60 min using chlorine charged gelatin microgel particles while equivalent free chlorine could only achieve 4 log CFU/cm2 inactivation during the same period. Overall, the results demonstrate potential of protein microgels for effective binding and delivery of chlorine to improve sanitation of wash water with suspended organics and food contact surfaces.