Influence of edible multilayer coatings with Opuntia stenopetala polysaccharides and Flourensia microphylla extract on the shelf-life of cherry tomato (Solanum lycopersicum L.)

Cherry tomatoes are popular fruits consumed raw, with a short shelf-life due to climacteric ripening and susceptibility to microorganisms. Multilayer edible coatings offer a postharvest preservation strategy, utilizing food-grade ingredients, such as polysaccharides from natural sources, allowing the incorporation of plant extracts as active ingredients. This study aimed to develop edible multilayer coatings of chitosan, and Opuntia stenopetala polysaccharides combined with alginate using layer-by-layer (LbL) technique, incorporating Flourensia microphylla extract, and evaluate its influence on the shelf-life of cherry tomatoes. Multilayer coatings were applied by immersion in polylactic acid films (PLA) for characterization of their properties and pre-evaluation. The coated PLA was characterized by contact angle, water vapor permeability (WVP), Fourier-transform infrared spectroscopy (FTIR), opacity, colour, confocal and scanning electronic microscopy (CLSM, SEM, respectively). Tomatoes were coated via LbL to evaluate shelf-life during 15 days at 22 °C. Physicochemical and microbiological analyses were performed to six treatments: uncoated, coated (with/without extract), and Fusarium oxysporum-inoculated fruits. Multilayer assembly was confirmed on PLA film through CLSM and contact angle, showing values below 70°. Acetylated amino and hydroxyl groups were observed on coatings by FTIR, which are characteristic of chitosan and F. microphylla, respectively. Coatings showed high transparency and WVP values of 8.21×10−12 and 8.09×10−12 g m−1s−1 Pa−1 for those with and without extract, respectively. Weight loss during shelf-life analysis were lower than 5 % for all treatments. The F. microphylla extract exhibited fungistatic effect, controlling F. oxysporum growth until day six of analysis. F. microphylla enhanced coating characteristics by adding antifungal properties, thus extending fruit shelf-life.