Combination of aerosolized acetic acid and chlorine dioxide-releasing film to inactivate Salmonella enterica and affect quality of tomatoes and Romaine lettuce

Authors: Fan, Xuetong; Jin, Zhonglin; Baik, Jessica; Gurtler, Joshua; Mukhopadhyay, Sudarsan

Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2021
Publication Date: 10/6/2021
Citation: Fan, X., Jin, Z.T., Baik, J.I., Gurtler, J., Mukhopadhyay, S. 2021. Combination of aerosolized acetic acid and chlorine dioxide-releasing film to inactivate Salmonella enterica and affect quality of tomatoes and Romaine lettuce. Journal of Food Safety. 41:e12922. https://doi.org/10.1111/jfs.12922.
DOI: https://doi.org/10.1111/jfs.12922

Interpretive Summary: Foodborne pathogens located on rough surfaces of fresh produce are difficult to inactivate. There is a need for more effective intervention technologies to reduce the population of pathogens on the surfaces. In the present study, a novel packaging system was developed using aerosolized acetic acid to trigger the release of gaseous chlorine dioxide from antimicrobial films inside packages. Both aerosolized acetic acid and gaseous chlorine dioxide were capable of inactivating Salmonella on tomatoes and lettuce, resulting in synergetic reductions of populations of the pathogen. Overall, the study provides the produce industry a novel method to enhance microbial safety of fresh produce.

Technical Abstract: Outbreaks of foodborne illnesses have continuously been found to be associated with fresh produce in recent years. Novel antimicrobial intervention technologies are needed to minimize the risk of pathogen contamination. The present study was undertaken to develop a novel in-package treatment system that combined aerosolized acetic acid and ClO2-releasing film in which the acid triggered the release of ClO2 from its precursor. Low amounts of the ClO2 precursor (10 mg sodium chlorite per film) was used to minimize residue ClO2 in packages to meet regulatory requirements, while acetic acid was aerosolized into the packages to increase its interaction with the ClO2 precursor. A four strain-cocktail of Salmonella enterica (S. Montevideo, S. Typhimurium, S. Newport, and S. Saint-paul) was inoculated onto the surfaces of cut Romaine lettuce and the stem scars of cherry tomatoes. The inoculated samples were placed into clamshell containers containing one ClO2-releasing film (2.5 x 2.5 cm). After the packages were sealed, acetic acid (2% and 4%) was aerosolized for 60 sec into the packages through perforated openings, activating the release of ClO2. The openings were then immediately sealed after treatments. Results demonstrated that the combination of acetic acid with the ClO2-releasing film significantly reduced Salmonella populations with reductions of >4 log and >2 log CFU/piece on lettuce and tomato stem scars, respectively. The ClO2 releasing film or aerosolized acetic acid, alone, did not result in any significant reductions of Salmonella on either produce item. Results from subsequent quality studies using uninoculated samples demonstrated that the combination treatments caused damage to fresh-cut Romaine lettuce during 14 days of storage at 10°C as evidenced by the deterioration in appearance, softening, and decreased ascorbic acid content and antioxidant levels (ferric reducing antioxidant power and oxygen radical absorbance capacity). The combination treatments of acetic acid and ClO2-releasing film did not significantly affect most of the quality attributes of tomatoes during 21 days of storage. Overall, our results demonstrate that the novel combination of acetic acid and ClO2-releasing film may be used to enhance microbial safety and quality of tomatoes, although optimum conditions need to be further modified to avoid quality deterioration.