PHYSICAL AND CHEMICAL PROPERTIES OF THE JUJUBE FRUITS AT DIFFERENT MATURATION STAGES

The effects of maturation stages on some physical and chemical properties of the jujube fruits were investigated. The maturation stages of the jujube fruits were described as green, yellow, half-red and red maturation. The physical properties and chemical composition of the jujube fruit significantly changed depending on the maturation stage. The size and weight of the jujube fruits increased, and the peel color changed from green to red with the maturation. The content of water-soluble vitamins, trans-resveratrol, total phenolic content and antioxidant capacity of the jujube fruits decreased during the maturation. The trans-resveratrol content of the jujube fruits was investigated for the first time and no trans-resveratrol content could be detected at red maturation stage. The major organic acid and sugar at the red maturation stage were found to be malic acid and sucrose, respectively. The phenolic composition also changed, but these changes showed unstable trend during the maturation. The major phenolic compound was catechin at the green maturation stage, whereas chlorogenic acid dominated at the red maturation stage. The jujube fruit is rich in minerals especially potassium and no changes in the mineral contents except for copper was observed between green and red maturation stages.