Antifungal activity of natural extracts and essential oils against Monilinia fructicola in vitro and as ingredients of pectin-based edible coatings for postharvest preservation of cold-stored nectarines

Abstract

The in vitro antifungal activity of different natural extracts and essential oils against Monilinia fructicola, the causal agent of brown rot of stone fruits, was evaluated as mycelial growth reduction on amended PDA plates. The most effective agents [lemongrass (LG), geraniol (GE), and Commiphora myrrha (MY)] were selected as antifungal ingredients of composite edible coatings (ECs) formulated with citrus pectin and beeswax. ECs were applied in in vivo curative experiments to ‘Lucibella’ nectarines artificially inoculated about 24 h before with M. fructicola. The EC with 0.2% GE was the most effective, with disease incidence reductions of 80 and 55% after 3 and 4 weeks of storage at 1 °C and 90% RH, respectively. Furthermore, this GE-EC reduced brown rot severity by up to 93% after 3 weeks. The LG-EC (0.4%) also reduced disease severity by 77% after 3 weeks. Regarding fruit quality, all tested ECs significantly reduced fruit weight loss and maintained higher firmness than control nectarines after 4 weeks at 1 °C plus 3 days at 20 °C, without adversely affecting the fruit physicochemical (titratable acidity, soluble solids content, and volatiles content) and sensory (overall flavor, off-flavors, firmness, and external aspect) quality. Moreover, the MY-EC provided higher gloss than the rest of ECs. These results can contribute to the development of new safe and eco-friendly commercial antifungal ECs to control major diseases and preserve postharvest quality of stone fruits.