|DONG, LIANGER - University Of Hawaii|
|LI, YONG - University Of Hawaii|
Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/9/2022
Publication Date: 3/14/2022
Publication URL: https://handle.nal.usda.gov/10113/7707561
Citation: Dong, L., Wall, M.M., Li, Y. 2022. Aqueous chlorine dioxide generated with organic acids have higher antimicrobial efficacy than those generated with inorganic acids. International Journal of Food Microbiology. 369. Article 109632. https://doi.org/10.1016/j.ijfoodmicro.2022.109632.
Interpretive Summary: Chlorine dioxide (ClO2) is used as a sanitizing agent in postharvest systems and is commonly generated by mixing sodium chlorite and acid. The antimicrobial effects of chlorine dioxide made with various organic and inorganic acids were evaluated for deactivation of three pathogenic bacteria in cell suspensions. This study showed differences in the inactivation of S. typhimurium, E. coli O157:H7, and L. monocytogenes by aqueous ClO2 generated with various food-grade acids. In tests of bacterial suspensions and artificially inoculated Romaine lettuce, food-grade organic acids produced aqueous ClO2 solutions with stronger antimicrobial properties than inorganic acids. A low dose (5 ppm) of ClO2 generated using lactic or malic acid was most effective against the three pathogens.
Technical Abstract: Chlorine dioxide (ClO2) is commonly generated by mixing sodium chlorite and acid. This study aimed to evaluate how acid affects the release kinetics and antimicrobial property of ClO2. Solutions made with weak acids released ClO2 more slowly and had higher stability than those made with hydrochloric acid. Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes were treated with 1, 2.5, and 5 ppm ClO2 for 3 or 5 min. Lettuce inoculated with the pathogenic bacteria were treated with 2.5 and 5 ppm ClO2 for 5 min. The effects of peptone load at 0.01% and 0.02% on the antimicrobial efficacy of ClO2 were investigated in S. Typhimurium cell suspensions. The contribution of excessive acids in the ClO2 solutions to bacterial reduction was also evaluated. 2.5 ppm ClO2 made with citric acid, lactic acid, and malic acid showed higher reductions in all three bacteria than ClO2 made with hydrochloric acid and sodium bisulfate. 5 ppm ClO2 produced with organic acids reduced populations of all bacterial strains from 7 log CFU/mL to undetectable level in 3 min, except S. Typhimurium treated by ClO2 produced with lactic acid. On inoculated Romaine lettuce, 5 ppm ClO2 produced with lactic acid and malic acid resulted in the highest reduction of E. coli O157:H7, S. Typhimurium, and L. monocytogenes of approximately 1.4, 1.7, and 2.4 log CFU/g, respectively. The antimicrobial efficacy of ClO2 made with HCl and NaHSO4 were affected by 0.01% and 0.02% peptone load, respectively. Food-grade organic acids produced aqueous ClO2 solutions with stronger antimicrobial properties than inorganic acids. Organic acids and ClO2 may have synergistic antimicrobial effects on pathogenic bacteria since the excessive acids in the ClO2 solutions alone did not show significant bacterial reductions.