Controlled sustained release of chlorine dioxide gas from extrusion-cast polymeric films to extend shelf life of strawberries

• Extrusion casting process used to produce ClO 2 gas release active films. • Films exhibited a sustained and controllable release of ClO 2 lasting 30 d. • ClO 2 release films extended strawberry shelf life to 14 d while preserving quality. • Films showed strong antimicrobial activity against E. coli and B. cinerea. • Films maintained their mechanical/thermal properties, ensuring processability. This study investigated the production and efficacy of two-layer films that emit chlorine dioxide (ClO 2 ) gas in a sustained manner to extend the shelf life of strawberries. Two-layer active films were manufactured via extrusion casting by incorporating varying mass fractions of citric acid (CA) (5–10 %) in an ethylene-vinyl acetate (EVA) layer and sodium chlorite (NaClO 2 ) (5–20 %) in a low-density polyethylene (LDPE) layer as precursors for ClO 2 gas generation. The developed films exhibited sustained ClO 2 gas release for up to 30 d, with release profiles strongly influenced by humidity, temperature, and precursor concentration. In vitro assays demonstrated that films containing 7.5–10 % CA and 15–20 % NaClO 2 achieved more than a 5-log CFU reduction of Escherichia coli , and the film containing 10 % CA and 20 % NaClO 2 resulted in complete inhibition of Botrytis cinerea mycelial growth. When applied in a strawberry storage study at 4°C, the active film containing 7.5 % CA and 15 % NaClO 2 prolonged shelf life up to 14 d by suppressing yeast and mold counts to below 3 log CFU g -1 , compared to 6.2 log CFU g -1 in control samples, while maintaining visual appearance and key fruit quality attributes. Given that the mechanical and thermal properties of these active films are comparable to those of conventional food packaging materials, the developed ClO 2 gas-emitting films represent a promising antimicrobial packaging approach for the preservation of fresh produce.