Aqueous chlorine dioxide treatment of horticultural produce: Effects on microbial safety and produce quality-A review

Abstract

Microbial load on fresh fruit and vegetables causes decay and losses after harvest and may lead to foodborne illness in case of contamination with human pathogens on raw consumed produces. Washing with tap water only marginally reduces microorganisms attached to produce surfaces. Chlorine is widely used for decontamination on fresh horticultural produces. However, due to harmful by-products and the questionable efficacy it has become increasingly challenged. During the last 20 years, the interest to study ClO₂ treatments as an alternative sanitation agent for industrially prepared fresh produce has largely increased. For a wide range of commodities, the application of gaseous ClO₂ has meanwhile been investigated. In addition, since several years, the interest in aqueous ClO₂ treatments has further risen because of the better manageability in postharvest processing lines compared to gaseous application. This article critically evaluated the effects of postharvest application of aqueous ClO₂, either alone or in combination with other treatments, on microbial loads for various horticultural produces. In laboratory investigations, application of aqueous ClO₂ at concentrations between 3 and 100 ppm effectively reduced counts of natural or inoculated microorganisms (bacteria, yeasts, and mold) in the range of 1 and 5 log. However, various effects of ClO₂ treatments on produce quality have been described. These mainly comprise implication on sensory and visual attributes. In this context, there is increasing focus on the potential impacts of aqueous ClO₂ on relevant nutritional components of produces such as organic acids or phenolic substances.

Keywords: Chlorine dioxide; aqueous treatment; fresh produce; human pathogen; microbial load; sanitizer.