Properties of beeswax antifungal coatings obtained by high-pressure homogenisation and their application for preserving bananas during storage

Abstract

Bananas are tropical fruits that are perishable and susceptible to fungal diseases, mainly caused by Colletotrichum musae. Antimicrobial emulsion-based coating materials have been used extensively to inhibit the growth of these fungi and extend the shelf life of bananas. Targeted emulsion-based film functionalities offer excellent mechanical, physicochemical and barrier properties and limit fungal growth kinetics. Antifungal compounds, such as essential oils or phenolic compounds, are added to emulsion-based (wax/biopolymer) coatings to enhance their antimicrobial properties. This study set out to formulate a beeswax-based emulsion for banana coatings using high-pressure homogenisation (HPH) and hydrophilic food-grade/organic coating materials. The particle size distribution, stability and mechanical properties of the film-forming emulsions, water vapour and the oxygen permeabilities of the resulting coating were investigated. The most promising sucrose emulsions were tested as coatings on banana fruits to assess their efficacy against moisture and firmness loss during storage. Adding thymol (0.5% w/w) to the sucrose emulsions further enhanced the inhibition of Colletotrichum musae growth to its barest minimum of <20%. Emulsion stability was clearly enhanced using HPH while the best inhibition was obtained with a 20% diluted sucrose emulsion containing 0.5% thymol, with or without HPH.