Combined essential oil treatments preserve physicochemical quality and reduce gray mold incidence in postharvest table grapes

Postharvest dip application of essential oil (EO) components represents an emerging strategy for modulating the physicochemical quality of table grapes, yet whether thymol (T), eugenol (O), and 1,8-cineole (S), applied singly or in combination at 0.125% (v/v), can simultaneously maintain berry quality attributes and suppress Botrytis cinerea -related deterioration in Vitis vinifera cultivars adapted to distinct terroir conditions remains unresolved. The present study examined the effects of a 15-min dip treatment with these EO components, applied individually and in all binary and ternary combinations, alongside B. cinerea inoculation ( F ; 1 × 10 ⁵ conidia/mL), on quality parameters, total soluble solids (TSS, °Brix), pH, titratable acidity (TA), berry firmness, and color coordinates ( L *, a *, b *), of cvs. ‘Karaerik’ and ‘Narince’ stored at +4°C with 90 ± 5% relative humidity for 20 days. EO treatments effectively preserved physicochemical integrity across both cultivars, with TSS peaking at 25.5% under O + S + F and T + O + S + F in ‘Narince’ and at 20.5% under T + O + S in ‘Karaerik’, and TA reaching 8.38 and 16.55% respectively under the same ternary combination, and, consistent with this sustained quality retention, combined applications outperformed single-component treatments in limiting B. cinerea -driven deterioration. Storage-induced responses were equally substantial: L values declined progressively while a, b, and firmness increased across both varieties, and the application × storage time interaction was statistically significant for TSS, pH, and TA, pointing to a time-dependent modulation of treatment efficacy. The two cultivars exhibited distinct physicochemical response profiles, with ‘Karaerik’ displaying higher constitutive acidity more substantially preserved by ternary combinations and ‘Narince’ showing greater TSS responsiveness to fungal-challenge treatments. Postharvest dip application of EO components significantly modulated postharvest quality maintenance and gray mold suppression, and overall berry quality could, at least partially, be controlled by selecting a cultivar-specific optimal formulation, with ternary combinations representing the most promising natural alternative to synthetic fungicides for postharvest grape disease management.