•Polysaccharidic coatings improve postharvest quality of zucchini fruit.•Dextrin enhances antioxidant defence diminishing chilling injury during storage.•Additives olive oil and oleuropein increase the ascorbate and phenolics content.•Dextrin-based coatings improve the nutraceutical properties of zucchini fruit. The use of edible coatings has surged as a response to the ever-increasing demand for ecologically-friendly methods for maintaining fruit quality during storage. This study analyses the application of different polysaccharide-based coatings, carboxymethylcellulose, chitosan, dextrin and starch, and the use of a plasticizer agent, glycerol, with dextrin shown to be the most effective in maintaining the postharvest quality of zucchini fruit during cold storage. Subsequently, to improve these results, the nutraceutical additives oleuropein and olive oil, were tested in combination with dextrin. Results showed that dextrin coatings reduced weight loss, chilling injury, and oxidative stress in zucchini fruit at low temperature, maintaining fruit quality. The natural additives obtained from the olive tree showed a higher induction of antioxidant enzymes as well as a greater accumulation of ascorbate and total phenolics, with the dextrin coating with olive oil being even more effective in maintaining the chilling injury low until the end of storage, associated to phenolic metabolism. This type of preservation could be implemented for extending postharvest life and enhancing the overall quality of zucchini fruit.