Abstract:

In order to discover the dynamic changes of phenolic compounds and antioxidant capacity during fruit
development of different jujube cultivars, the contents of total phenolics, flavanoids, vitamin C and individual phenolic
compounds as well as antioxidant capacity of jujube fruits from six cultivars such as Huizao, Jixinzao, Lizao, Zanhuangzao,
Mopanzao, and Huluzao, were determined at the stages of young fruit, green maturity, white maturity, half-red maturity,
and red maturity. Results showed that the contents of total pehnolics, flavanoids, vitamin C and antioxidant capacity of all
tested cultivars of jujube fruits were the highest at young fruit period and decreased during fruit development. The contents
of total phenolics and flavanoids decreased rapidly before green maturity and then declined slowly. Above 60% of the
declines in total phenolics and flavanoids contents were found in mature jujube fruit as compared with the young fruit.
However, the content of vitamin C and antioxidant capacity decreased rapidly before white maturity and thereafter declined
slowly. Catechin, epcatechin and lutin were the major phenolic compounds in the tested jujube fruits as analyzed by high
performance liquid chromatography. They also showed descending trends with development of jujube fruits. But there was a
significant difference among the cultivars tested. Correlation analysis between the contents of total phenolics, flavanoids, catechin,
epicatechin, lutin and vitamin C and antioxidant capacity revealed that there were significantly positive correlations between the
antioxidant capacity and the contents of total phenolics, flavanoids, catechin, epicatechin, lutin and vitamin C. High correlation
coefficients were obtained between antioxidant capacity and the contents of catechin, epicatechin, and lutin, indicating that they
are the major determinants of antioxidant capacity in jujube fruit. Furthermore, high content of phenolic compounds and strong
antioxidant capacity were found in fruits of the cultivars Mopanzao and Huluzao, while the fruit of Jixinzao contains higher content
of vitamin C. Thus, they are the promising varieties for production of functional jujube fruits or processed products with health benefits.

Key words: jujube, total polyphenol, total flavanoid, antioxidant, development