Physicochemical Properties and Nutritional Value of Jujube (Ziziphus jujuba Mill.) Fruit at Different Maturity and Ripening Stages

Jujube (Ziziphus jujuba Mill.) fruit is an important medicinal plant in Iran. The harvesting time is a crucial for jujube fruit quality. Several characteristics of jujube fruit when harvested at four development stages; white mature (light green), crisp mature (whitered), fully mature (red) and fully ripe (dehydrated brown) were evaluated. Fruit weight, diameter, volume, pulp to stone ratio, firmness, titratable acidity (TA), total soluble solids (TSS), ascorbic acid, total phenolics content, protein, ash and chlorophyll fluorescence parameters were determined. The results showed that fruit dry weight, TSS, TSS/TA were increased significantly, while firmness, protein content and ash weight were decreased as jujube fruit harvested at progressed development stages. Ascorbic acid in fruit was decreased from white to crisp mature stage and thereafter increased significantly to fully mature stage. However, the content of total phenol increased significantly from white to crisp mature stage and thereafter decreased at more maturity and ripening stages. Moreover, chlorophyll fluorescence parameters were influenced by harvesting time. The F0 and Fm showed a positive significant correlation with total phenolic, ascorbic acid and protein content and a negative significant correlation with DW. Therefore, chlorophyll fluorescence maybe a helpful, nondestructive technique to evaluate the nutritional quality changes in jujube fruit. Overall, jujube fruit harvested at crisp (whitered) and fully mature (red) stages, seem best in respect of postharvest handling and nutritional criteria.