Postharvest Quality Extension of Minimally Processed Table Grapes by Chitosan Coating

Demand for fresh grapes is increasing globally due to their rich composition in phenolic compounds, which have a strong antioxidant capacity. However, fresh table grapes deteriorate rapidly due to berry water loss and pathogen growth, which make it difficult to preserve without treatment. Chitosan coating, as a healthy, simple and innovative technology against to common SO2 fumigation, was tested at various concentrations (0%, 0.5%, 1.0% and 2.0%) for the effectiveness on postharvest quality extension of detached grapes of ‘Alphonse Lavallée’ cultivar. Chitosan coating at all doses significantly retarded the loss in berry weight, extended the skin rupture force and total phenol content. Visual quality was higher due to coating the berries with chitosan. Chitosan at all concentrations was effective on delaying maturity index (used to express postharvest senescence) and changes in berry colour values such as L*, C and Hue angle. Among the applied doses, 1% chitosan solution can be recommended to apply since higher doses were more effective with similar results on overall quality features of berries. Overall findings demonstrated that chitosan as an edible coating with their unique barrier can be utilized as a natural preservative of detached grapes to extend the postharvest quality up to 28 days.