Influence of edible carboxymethyl cellulose coatings incorporating blueberry extract on the postharvest shelf life of two Vaccinium corymbosum L. cultivars (‘Duke’ and ‘Draper’)

Blueberry ( Vaccinium corymbosum L.) is a perishable fruit that deteriorates rapidly after harvest. This study aimed to develop and characterise an edible coating based on 1.75 % carboxymethylcellulose (CMC) enriched with 0.25 % blueberry extract (BE) and to evaluate its efficacy in postharvest quality of ‘Duke’ and ‘Draper’ blueberries during cold storage (4 °C). The film's characterisation results showed that CMC + BE presented 26 % lower water vapour permeability and 50 % higher elongation at break than the CMC film. BE demonstrated dose-dependent antioxidant capacity (14.04–37.68 % DPPH • inhibition), and antifungal activity against Botrytis cinerea (18.54–65.99 % inhibition). Although the coatings did not significantly reduce weight loss, they effectively preserved fruit firmness in both cultivars, with CMC + BE showing a 41–48 % increase relative to the control. Lower pH and maturity index values indicated that the coatings delayed the metabolic senescence of ‘Duke’ blueberries. Total phenolic content and antioxidant capacity increased immediately after the application of CMC + BE, indicating a contribution from the extract's bioactive compounds. Also, L * and C * values decreased mainly due to the coatings’ optical effects, while no significant sensory differences were observed between samples, indicating that acceptability was maintained during storage. In conclusion, the postharvest application of CMC enriched with BE is an effective strategy for improving blueberries’ shelf life while valorising agricultural by-products.