Scalable Citral and Lemongrass Essential Oil Nanocapsules for Gray Mold Control in Grapes

Gray mold is a serious economic-impact fungal disease caused by Botrytis cinerea that threatens the quality and storage life of a wide range of fruits and vegetables. Currently, pathogen control relies heavily on synthetic fungicides, raising environmental and health concerns. This study explores the development and evaluation of poly(lactic acid) (PLA) nanocapsules loaded with citral, a natural compound found in plant essential oils that has been shown to have antifungal properties. PLA-encapsulated lemongrass essential oil (LGEO) was also evaluated as a natural citral-containing substance. The nanoencapsulated systems were successfully formulated in 2 L batches, yielding stable colloidal suspensions with mean diameters from 220 to 224 nm and encapsulation efficiencies from 84 to 87%. The antifungal activity was first assessed by in vitro conidial germination assays, which showed complete inhibition was achieved at concentrations ≥ 0.05% (v/v) for both encapsulated and non-encapsulated citral and LGEO. Subsequently, the effectiveness of the nanoencapsulated citral and LGEO in preventing gray mold was evaluated using Vitis vinifera grapes inoculated with B. cinerea . The results revealed that nanoencapsulation proved remarkably superior: citral- and LGEO-loaded nanocapsules reduced lesion diameters by up to 72% and 63%, respectively, after 168 h of storage. In contrast, free citral and LGEO showed limited efficacy against gray mold. These findings highlighted the potential of nanoencapsulation as a strategy to enhance the efficacy and safety of bioactive terpenes as alternative, sustainable fungicides for postharvest disease management.