Bioactive coating of sodium alginate and agar added with essential oils of thyme (thymus vulgaris l.) and sweet orange (citrus aurantium var. dulcis) with antimicrobial properties applied over strawberries

Minimally processed strawberries have high acceptability but a short shelf life. The application of edible coatings with essential oils may be an alternative to preserve these fruits. Our objective was to develop, apply and characterize the effect of bioactive edible coatings based on agar or sodium alginate with thyme and/or sweet orange essential oils with antimicrobial properties, mainly against Listeria monocytogenes, for strawberries. The effect of the coatings on the physicochemical, microbiological, and sensory properties that determine the shelf life of strawberries was verified at 1, 8, and 15 days. The effect against Listeria monocytogenes bacteria in strawberries artificially contaminated with this microorganism was also evaluated. Thyme and sweet orange essential oils had thymol and D-limonene, respectively, as main components. Alginate coating with sweet orange and thyme essential oil showed the best results. For Listeria monocytogenes, the coating applied after fruit contamination had an antimicrobial effect.