Pre‐ and postharvest chitosan coatings extend the physicochemical and bioactive qualities of minimally processed ‘Crimson Seedless’ grapes during cold storage

BACKGROUND Food marketers desire residue‐free fresh grapes although grapes have a short postharvest life. This study was performed to determine the influences of pre‐ and/or postharvest chitosan (Ch) coatings on postharvest quality of minimally processed (stem‐detached) organic ‘Crimson Seedless’ berries. Berries were sorted as: (a) control (untreated berries); (b) preharvest Ch (dipping the clusters on the vine into 1% Ch 10 days before harvest at 20% soluble solid content (SSC)); (c) postharvest Ch (dipping the stem‐detached berries into 1% Ch); and (d) pre + postharvest Ch. Berries were stored in 12 × 15 cm rigid polypropylene cups for up to 42 days at 1.0 ± 0.5 °C. RESULTS Pre‐ and/or postharvest Ch coating reduced weight loss during storage. Pre‐ + postharvest Ch was the best treatment for restricting polygalacturonase (PG) activity, extending the visual quality, color features (L*, C and h°), skin rupture force, biochemical (SSC, titratable acidity, maturity index and pH) and bioactive (total phenol content, antioxidant activity) features. Pre‐ or postharvest Ch was also significantly effective in maintaining many quality features. CONCLUSION Pre‐ and/or postharvest 1% Ch coatings effectively maintained the quality of minimally processed grape berries of organically produced ‘Crimson Seedless’ grapes by delaying weight loss and PG activity and keeping the postharvest physical, biochemical and bioactive features for 42‐day cold storage at 1.0 ± 0.5 °C. The combined use of pre‐ and postharvest Ch found to be more effective than single treatment. Thus, pre‐ + postharvest 1% Ch coating could be recommended as an ecofriendly sustainable methodology for extending the postharvest quality of minimally processed fresh grapes. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.