Efficacy of an edible coating, containing thyme essential oil, to control Fusarium oxysporum and the quality of tomato fruits

The present study aims to evaluate the antifungal activity of Thymus vulgaris essential oil and its CMC-based coating against Fusarium cf. oxysporum , the most pathogenic fungus in tomato fruits in Tehran markets. The effect of the coating on the physicochemical properties of tomato fruits was evaluated. The phytochemicals of the essential oil were also determined and qualified by GC and GC–MS methods. Based on the results, thymol (42.98%), p -cymene (28.58%), and γ -terpinene (22.78%) were identified as major components of the oil. Thyme essential oil inhibited spore germination of F. oxysporum with an IC 50 value of 0.079 µg/mL, more potent than kresoxim-methyl (0.106 µg/mL), as a standard antifungal agent. Also, the essential oil exhibited a high mycelial growth inhibitory activity and showed fungicidal activities at low volumes. In addition, the formulated coating (0.5% essential oil) prevented the growth of fungal infection with 85.31% inhibition in inoculated tomatoes after 9 days. After different storage periods (11- and 17-days), lower mass loss, higher titratable acidity, lower total soluble solid content, and lower lycopene content of coated fruits were observed in comparison with uncoated ones. This proved that the coating can increase the shelf life of the fruits, by providing a semi-permeable film around them. The results suggest that by using this product as an edible coating, the fungal infections and ripening process can be controlled and the storage life of tomatoes can be extended effectively. Graphical abstract