Edible coatings based on solid lipid nanoparticles containing essential oil to improve antimicrobial activity, shelf-life, and quality of strawberries

Abstract

Fungal rot is a major global health concern, particularly in delicate and soft-textured fruits such as strawberries. This study aimed to assess the effectiveness of coatings containing different levels of free essential oil of Mentha × piperita L. (MEO) and solid lipid nanoparticles carrying MEO (MEO-SLNs) on the microbial load, storage quality, and shelf life of strawberries (Fragaria × ananassa cv. Camarosa) for 20 days at 8 °C. The study evaluated several factors, including weight loss, firmness, color, ascorbic acid, phenolic content, antioxidant activity, microbial load, cellulase, catalase, polyphenol oxidase, and sensory properties at regular intervals. The results indicated that strawberries treated with MEO-SLN at a concentration of 0.2% exhibited the lowest weight loss (approximately 78%), the highest firmness (around 45%), the greatest antioxidant activity (about 98%), and the highest ascorbic acid content (approximately 41%) compared to the control group. This treatment also preserved the levels of total phenol and catalase activity, reduced the activity of cellulase and polyphenol oxidase, and delayed color development. Furthermore, strawberries treated with MEO-SLN at a concentration of 0.2% received higher ratings for texture firmness, freshness, taste, appearance, and overall acceptance, and showed a lower number of cfu (colony-forming units) on day 20 of storage. MEO-SLN treatments showed no signs of soft spoilage in artificially contaminated strawberries during storage. These findings suggest that the use of MEO-SLN coatings can effectively maintain the postharvest quality of strawberries, decrease spoilage, and extend the shelf life and nutritional value of the fruits during cold storage.