In-package release of gaseous chlorine dioxide for improving the safety and shelf-life of grape tomatoes

Films containing sodium chlorite powder (0.25 g/film) were developed by three methods: solvent method, hydraulic press method, or water dissolution followed by paper absorption. Their antimicrobial effectiveness against E. coli, Listeria, Salmonella and native microflora on tomato stem scars was evaluated. The release of ClO₂ gas was activated directly by adding an acid solution to the films, or indirectly by acid vapors absorbed by the films. The absorbed paper film achieved the greatest microbial reduction (>5 log CFU/g), followed by the pressed film (4.5 log reduction), and the film made by solvent had the least reduction (3.2 log reduction). Interestingly, the absorbed paper film was activated by tomatoes in the absence of any external acid activators. Tomatoes treated with the absorbed paper film had undetectable spoilage microflora (<1 log CFU/g) after 21 days of storage at 10 °C. Furthermore, the quality evaluation of tomatoes indicated that the film-treated samples had similar color to untreated controls but had a firmer texture and less weight loss than the controls after 21 days. These results demonstrate that the antimicrobial effectiveness of sodium chlorite-containing films depends on the process with which they are prepared. The absorbed paper film not only showed the greatest antimicrobial activity but also did not require an external acid activator for it to be effective. This method provides a simple and economical way to produce antimicrobial materials that can be used across various food types to inactivate foodborne pathogens and spoilage microorganisms, enhancing food safety and extending shelf life.