Modulation of chlorine dioxide foam activity by surfactant type: Chemical interactions affecting bactericidal efficacy against Salmonella enterica

Chlorine dioxide (ClO 2 ) is widely used for sanitizing food-contact surfaces, but studies on ClO 2 foam formulations are limited. In particular, the effect of surfactants, which are required to generate foam, on the antimicrobial activity of ClO 2 foam has not been extensively investigated. This study examined the effects of various surfactants on the antimicrobial efficacy of chlorine dioxide (ClO 2 ) foam against Salmonella enterica on stainless steel surfaces. ClO 2 solutions at 100 and 200 μg/mL showed significant bactericidal activity, achieving up to complete sterilization at 200 μg/mL. Surfactants from four classes including anionic (sodium dodecyl sulfate), cationic (cetylpyridinium chloride and cetyltrimethylammonium bromide), amphoteric (coco betaine and lauryl betaine), and nonionic (Triton X-100 and Tween 80) were evaluated in foam formulations. Amphoteric surfactants enhanced the antimicrobial effect of ClO 2 most effectively, resulting in reductions of up to 4.1 log CFU per coupon. Cationic surfactants also improved efficacy, while nonionic surfactants reduced it. Although surfactants decreased ClO 2 concentration by approximately 10%, antimicrobial performance remained highest with amphoteric surfactants. These findings demonstrate how surfactant chemistry influences ClO 2 foam sanitizers and provide guidance for the design of effective disinfection systems for food-contact surfaces. • Effects of surfactants on the lethality of ClO 2 foam against S. enterica were studied. • CPC, CTAB, coco betaine, and lauryl betaine foams showed strong bactericidal activity. • ClO 2 foams containing amphoteric surfactants showed the highest antimicrobial effect. • ClO 2 foams containing nonionic surfactants showed decreased antimicrobial activity.