Research PaperActive chitosan/PVA with ascorbic acid and berry quality of 'Superior seedless' grapes

- Evaluate the influence of chitosan/PVA loaded with ascorbic acid at different concentrations as a postharvest coating treatment on 'Superior seedless' grape cultivars.
- Chitosan is one of them as a biopolymer that is non-toxic and has antimicrobial properties. Also, it is a good tool to provide a protection to fruit during handling and packaging processes.
- Using a combination of chitosan/PVA coatings as the best edible method and biologically safe preservative coatings for different types of fruits, with physiological advantages, such as lower respiration rates, extended storage periods, and firmness retention.
- And it extend the postharvest life of fruit by reducing water loss, gas exchange, and oxidative reaction rate.
- Considering that chitosan and PVA can be safely used for postharvest of fruits and that natural extracts can be incorporated into chitosan/PVA blends.

The effectiveness of chitosan/polyvinyl alcohol (CS/PVA) blended with ascorbic acid (AA) at different concentration (0, 2.8, 5.6 and 8.2 mM) of 'Superior seedless' grapes coating to delay deterioration of fruit cluster during shelf-life. Clusters were coated with different treatment CS/PVA-AA solution and stored at room temperature for four days. Samples were taken every day. Physico-chemical, weight loss, soluble solid content (SSC%) and titratable acidity (TA), berry firmness and separation force and nutraceutical such total polyphenol (TP), flavonoid (TFL) content, polyphenol oxidase (PPO) and rachis browning index properties along with the cell wall degrading enzymatic activity cellulase (CEL), polygalacturonase (PG) and xylanase (XLN) and cell membrane permeability were evaluated. CS/PVA-AA 8.2 mM treatment significantly reduced water loss, berry shattering and delayed the qualitative changes in color, SSC, TA and SSC/TA ratio content. Additionally, changes in the TP, TFL contents are related to AA loaded with CS/PVA coating to fruits clusters were delayed. CS/PVA-AA coating could be enhanced the activity of some antioxidant enzymes, preventing rachis browning and reducing membrane damage by inhibition of cell wall degrading CEL, PG, and XLN. Also, CS/PVA-AA 8.2 mM coating fruit cluster of superior seedless grapes exhibited a slower rate of deterioration, compared to uncoated fruit clusters and CS/PVA-AA only.