Lemongrass essential oil and aloe vera gel based antimicrobial coatings for date fruits

In fruit processing industry, edible coatings/films are usually applied on various fruits to provide protection against microorganisms and to regulate various biological functions of the fruit. The current research in this domain is more focused on exploring naturally occurring bioactive materials to develop active edible coatings that can offer an extended functionality than just providing barrier properties. Therefore, here we report the application of aloe vera gel-based edible coatings, either as standalone or in combination with lemongrass essential oil to enhance the shelf life of the soft date fruit variety (as soft dates are usually more prone to spoilage). The pure aloe vera gel coatings were aqueous mixtures of 25% aloe vera gel; whereas, nanoemulsion-based coatings of lemongrass essential oil (1-5%) and aloe vera gel (25% aqueous mixture) were prepared through a high-pressure homogenizer. After preliminary physicochemical characterization of the prepared coating mixtures, the date fruit samples were dipped in coating mixtures, dried, and then stored at room temperature for 4 weeks. The analyses of date fruits during the storage revealed that the applied coatings did help in retention of physicochemical attributes (e.g., moisture, texture, and pH) and also significantly prevented microbial growth. More specifically, the nanoemulsions based coatings of lemongrass essential oil (up to 3%) and aloe vera gel exhibited excellent antifungal properties, which is quite remarkable as the date fruits are usually more susceptible to fungal growth than the bacterial growth. Based on these findings, the date fruit processing industry can utilize these natural antimicrobial coatings for the shelf life extension of date fruits.