Plum-gum, a promising biomaterial for preserving the postharvest quality of fresh ‘Valencia’ oranges

In response to mechanical injury, environmental stress or pathogenic fungi, several woody plants produce gums, rich in terpenoids, hydroxyproline-rich proteins, resins and carbohydrate components. Edible coatings and films, developed from the plant extracts, have been extensively used to preserve postharvest quality of fruits and vegetables and different biomaterials have been reported to have high potentials. Since the scientific confirmation of the negative effects of miss-/extensive-use of agrochemicals, plant derived biomaterials have begun to replace those agrochemicals due to their environmentally friendly, biodegradable and safety characteristics. The present study was conducted to evaluate the potential of plum-gum coating in maintaining postharvest quality of ‘Valencia’ oranges. Three different concentrations of plum-gum (1, 5 and 10%, w/v) together with control were tested in current work. Results suggested that all doses of plum-gum application were effective in reducing the weight loss and preventing the loss in fruit firmness. Significant effect was also observed for the prevention of decay incidence and loss of visual quality. The effects of plum-gum application on the soluble solids concentration and titratable acidity were not as effective as on the other quality parameters. The application of plum-gum was also found to be effective in reducing the respiration rate and caused a significant increase in the ascorbic acid content of the stored fruits. Overall, results suggested that the lowest concentration of the plum-gum was sufficient to significantly improve the storability of ‘Valencia’ oranges.