Enhancement of Post-harvest Quality of Fresh Mandarins with Alginate-Based Edible Coating Containing Natamycin and Vanillin

Environmentally friendly technologies with regard to reducing the usage of commercial synthetic waxes are required for maintaining the quality of mandarin fruits during the post-harvest period. In this study, novel biocoatings that serve as a natural alternative to synthetic waxes were developed for obtaining sustained shelf life of freshly harvested mandarins. The effect of natamycin and vanillin as natural antimicrobial compounds on the post-harvest quality of mandarins were investigated by means of alginate-based edible coating. Alginate coating (1% w/v) formulations including 0.5% vanillin, 1.0% vanillin, 0.025% natamycin, 0.05% natamycin and without vanillin or natamycin were applied and compared with uncoated fruit as control. Weight loss, color change, fruit firmness, yeast and mold counts were examined over 21 days at 25 °C. Quality changes in mandarins such as losses of weight, color and softening changes were significantly delayed with alginate coatings. Brightness on the surfaces of fruits was improved by alginate coating layers. Fruit firmness decreased with storage time in control samples, while the firmness in coated samples remained relatively constant or increased. Moreover, yeast and mold counts considerably decreased (1.52 log cfu/g) for fruits coated with alginate coating incorporating 1% vanillin. Extension of the post-harvest storage of mandarin fruits could be performed by using alginate coating incorporating vanillin as an alternative to synthetic waxes.