Guar gum and essential oil-based composite coatings preserve antioxidant enzymes activity and postharvest quality of kinnow Mandarin

Kinnow mandarin is a perishable fruit and is prone to various postharvest losses during storage and transportation. To address this issue, the effect of composite coatings of guar gum (GG) and lemongrass essential oil (LGO) on the quality and longevity of Kinnow mandarins was investigated. The findings showed that as compared to uncoated fruits, the GG 1.0% + LGO 1.0% coated fruits had less spoilage (3.01%), weight loss (7.21%), and lipid peroxidation rate (1.10 mmol g−1) while retaining higher levels of ascorbic acid, sensory quality, total soluble solids, flavonoids, and total antioxidant activity at the end of storage. The coated fruits also exhibited higher enzymatic activities of the superoxide dismutase (42.65 U min−1 g−1), phenylalanine ammonia-lyase (224 U h−1 g−1), peroxidase (35.21 U min−1 g−1), and catalase (47.65 U min−1 g−1). Furthermore, scanning electron microscopy (SEM) revealed a smooth and even layer in the composite-coated fruits, whereas uncoated fruits showed open stomata and cracks. These results indicate that coatings made of GG 1.0% and LGO 1.0% have the potential to preserve the qualitative features of Kinnow fruits stored at low temperatures. [Display omitted]