Antifungal effect of a natural coating of carnauba wax–aloe vera emulsion with essential oils: A strategy to control gray mold and extend tomato shelf life

Abstract

Tomato (Solanum lycopersicum L.) is a major global crop valued for its nutritional and commercial importance but is highly susceptible to postharvest fungal infections, particularly gray mold caused by Botrytis cinerea. This disease compromises fruit quality, reduces shelf life, and generates significant economic losses. This study evaluated natural coatings based on a carnauba wax–Aloe vera emulsion supplemented with cassia and/or Mexican lime essential oils (EOs) for their effects on gray mold development and tomato postharvest quality. Thiabendazole (TBZ) and the commercial coating Aloecoat® were used as controls. In vitro analyses showed that EOs inhibited 100 % the growth of B. cinerea, demonstrating a synergistic effect when combined, which reduced by eightfold the concentration needed to inhibit mycelial growth and spore germination. Confocal fluorescence microscopy showed that the antifungal effect of the treatments is associated with the cell membrane. In vivo assays revealed that EO emulsions significantly outperformed TBZ and Aloecoat®, reducing gray mold incidence to 8.3 % compared with 33.3 % and 100 %, respectively (P ≤ 0.05). They also decreased disease severity (1.16 % to 7.5 %). EOs reduced weight loss (5.88 %–6.82 %) relative to TBZ (6.36 %) and Aloecoat® (10.91 %), maintained higher firmness (21.91–24.36 N) compared to TBZ (10.51 N) and Aloecoat® (9.36 N), and exhibited higher total soluble solids (4.06–4.16°Brix) and brightness (up to 40.78), clearly outperforming the control treatments (P ≤ 0.05). These findings highlight essential oil–based emulsions as effective natural alternatives to synthetic and commercial coatings, offering improved quality preservation, extended shelf life, and gray mold control, with reduced environmental impact.