Preparation and Characterization of Chlorine Dioxide-releasing Antimicrobial and Antifungal Paper-based Sachet Coated with Sodium Caseinate and Spent Coffee Grounds

Chlorine dioxide (ClO₂) is widely used for the surface sterilization of fresh foods due to its strong oxidative capacity and high solubility. In this study, active sachets capable of releasing ClO2 were prepared by coating paper with TEMPO (2,2,6,6-Tetramethylpiperidin-1-oxyl) oxidized spent coffee grounds (TOSCGs) and sodium caseinate (CasNa). The moisture adsorption properties, chemical structure, morphological properties, and water vapor barrier properties were evaluated. The result showed that increasing the TOSCGs content strengthened intermolecular interactions, decreased water vapor permeability and enhanced moisture adsorption capacity under high humidity conditions. Sachet containing sodium chlorite and citric acid showed effective antibacterial and antifungal activity against E. coli, S. aureus, and A. niger under both contact and non-contact conditions, and the effect of inhibiting spoilage and extending storage life was confirmed in actual fresh fruit storage experiments. Therefore, the sachet developed in this study is an eco-friendly active packaging material using food by-products and will be able to contribute to maintaining the quality of fresh food through continuous antibacterial function.