Changes of composition and activity of oxidative enzymes in the pericarp and mechanism of ethanol accumulation in ′brumal jujube′

Ethanol accumulation was one of the primary deteriorated factor of fruit during storage of ′brumal jujube′. The relationship between changes of composition and activity of oxidative enzymes in the flesh and pericarp and ethanol accumulation in different maturity of ′brumal jujube′ were investigated. The results show that ascorbic acid oxidase activity in the flesh of ′brumal jujube′ is significantly higher than that in pericarp with the development of maturity; but these activities of peroxidase, polyphenoloxidase and phenylalanine ammonia-lyase in flesh are lower than those in pericarp. During the development from green to half-red then to red, the lignin and fibre content in pericarp gradually increase, higher than those in flesh; ethanol content also increases, acetaldehyde content reaches a peak during the red maturity stage and then declines. The relationships between ethanol accumulation, lignin content and the activity of oxidase during the ripening of ′brumal jujube′ are discussed.