Development of a corn protein-based novel antimicrobial chloramine coating for agricultural water disinfection

This study aimed to improve the recyclability of post-harvest agricultural wash water. To achieve this, a water disinfection system was developed using plastic beads coated with zein-based chloramine, a corn protein formulation designed to immobilize free chlorine. The project began with the preparation of antimicrobial beads, where high-density polyethylene (HDPE) plastic beads were immersed in a 3 % (wt/vol) zein solution and dried thoroughly in a food dehydrator. The resulting beads were chlorinated and assessed for the total chlorine retained within the zein coating, as well as the released free and combined chlorine. Additionally, the chlorinated zein-coated beads were analyzed for their shelf-life, recyclability, and antimicrobial efficacy. Furthermore, post-harvest citrus wash water was passed through a column packed with chlorinated zein-coated beads to inactivate inoculated surrogate microorganisms. The results revealed that the optimal formulation for zein-coated beads included a diameter size of 0.125 inches, a 1:3 beads-to-plate ratio, HDPE material, and a 3 % (wt/vol) zein-coating solution. In addition, the beads could go through 5 cycles of coating and chlorination, which emphasizes their potential for recyclability. Results for antimicrobial efficacy tests using agricultural water revealed that at least a 4.5-log reduction for Escherichia coli and a 3.5-log reduction for Listeria innocua could be achieved with minimal free chlorine released. Based on these results, chlorinated zein-coated beads have succeeded as a potential antimicrobial disinfection system for agricultural water. This disinfection system can potentially remove pathogenic bacteria from agricultural water while minimizing the concerns of disinfection byproducts (DBPs) generation. • Chlorinated zein-coated plastic beads were developed and optimized for antimicrobial treatment of agricultural water. • Zein chloramine coatings release minimal free chlorine, helping to reduce the concerns of disinfection by-product generation. • Zein-coated beads exhibit evident recyclability and long shelf-life potential, addressing sustainability concerns. • Chlorinated zein-coated beads effectively inactivate Escherichia coli and Listeria innocua in agricultural wash water.