Potassium Permanganate-Based Ethylene Scavengers for Fresh Horticultural Produce as an Active Packaging

Potassium permanganate (KMnO4) is a powerful ethylene (C2H4)-scavenging agent widely used in fresh horticultural commodities to delay the postharvest maturation. According to databases, it has been used for almost 50 years in food-packaging systems, and over 70 studies have evaluated its effects on fresh produce quality, mainly on climacteric fruit. However, the use of KMnO4-based technology remains limited at a commercial scale, since there are still lots of doubts on its potential as an effective postharvest tool, as well as in relation with health, environmental and safety concerns. Depending on the commodity, and even the variety, these scavengers may have different effects, but overall, they can delay ripening/senescence-related processes such as chlorophyll degradation/colour changes, weight and firmness losses, disorders and diseases, acidity and sugar changes. This review comprises an updated overview of the current knowledge regarding the use of KMnO4 as C2H4-scavenging agent, providing a concise appraisal on KMnO4-based C2H4 removal application and its effect on the quality of fresh produce. KMnO4 is commonly supported onto microporous mineral particles, which are placed into small sachets to avoid direct food contact within packages. Generally, KMnO4-based C2H4 scavengers are jointly used with modified atmosphere packaging. Hence, KMnO4-based C2H4-scavenging systems, as an active food-packaging technology, seem to be a relevant option to preserve the quality and safety of fresh horticultural produce. Nevertheless, although there are many KMnO4-based products available in the market, which are presently reviewed, more research is required in order to obtain an optimal C2H4-scavenger performance.