Enhancement of postharvest quality of Nam Dok Mai Si Thong mangoes using a turmeric-incorporated composite edible coating

• Turmeric powder addition enhanced phenolic content of composite coating solution. • Turmeric dispersed uniformly and formed microvoids within the polymer film. • Turmeric powder addition improved antifungal activity against Colletotrichum sp. • Turmeric and non-turmeric coatings slowed ripening and reduced rotting in mangoes. • Both coatings (C and CT) extended mango shelf life from 4 days to 6 and 12 days. This study developed a composite edible coating containing 0.5% turmeric powder to improve the postharvest quality of Nam Dok Mai Si Thong mangoes. The coating formulation consisted of pectin, hydroxypropyl methylcellulose, alginate and gelatin, with (CT) or without (C) turmeric. Incorporation of 0.5% turmeric significantly increased the viscosity and color values of the coating solution compared with C. The CT formulation exhibited markedly higher phenolic compounds, total phenolic content and antioxidant activities, with curcumin identified as the predominant phenolic compound (556.73 ± 0.06 µg/100 mL) ( p ≤ 0.05). SEM analysis confirmed the homogeneous dispersion of turmeric particles and revealed the presence of microvoids in CT films. In vitro assays showed that only CT displayed strong antifungal activity against Colletotrichum sp., producing an inhibition zone of 8.12 ± 0.05 mm. In vivo , mangoes coated with CT (CT-M) exhibited significantly smaller anthracnose lesion diameters (0.53 ± 0.06 cm) than C-M (5.27 ± 0.15 cm) and uncoated fruit (UC-M, 7.57 ± 0.15 cm) after 12 days of storage at ambient temperature (32 ± 2°C) ( p ≤ 0.05). Both coatings delayed ripening-associated changes in total soluble solids to titratable acidity ratio, firmness and color relative to UC-M. Notably, CT-M significantly reduced disease incidence, with anthracnose and stem-end rot indices of 20% and 0%, respectively. Consequently, shelf life was extended from approximately 4 days in UC-M to 6 days in C-M and up to 12 days in CT-M. These findings highlight the potential applicability of turmeric-based composite edible coatings for other climacteric fruits.