Phenolic compounds in the fruit of different varieties of Chinese jujube (Ziziphus jujubaMill.)

SummaryChinese jujube (Ziziphus jujuba Mill.) fruit were harvested at the fully mature stage from orchards in China in 2004, sundried and later investigated for their phenolic fingerprints. Phenolics were extracted from the following seven varieties of Z. jujuba Mill.: ‘Bianhesuanzao’, ‘Yuanlingzao’, ‘Fupingdazao’, ‘Zanhuangdazao’, ‘Zizao’, ‘Huizao’, and ‘Jinsixiaozao’, and from a variety of acid jujube [Z. jujuba Mill var. spinosa (Bunge) Hu et H. F. Chou]. Two phenolic acids from the hydroxycinnamate sub-class (chlorogenic acid and caffeic acid) and three flavonoids (catechin, epicatechin and rutin) were determined by high-performance liquid chromatography in extracts of dried Chinese jujube fruit. Among the varieties, considerable differences in the contents of each phenolic compound were confirmed. Acid jujube fruit had the highest content of hydroxycinnamic acids, as well rutin and epicatechin, while ‘Zizao’ had the highest catechin content. Consequently, acid jujube was the richest source of phenolics (i.e., the sum of all phenolics analysed was the highest), while ‘Jinsixiaozao’ was the poorest source. Jujube fruit were a good source of phenolics (especially flavonoids), comparable to prunes, and therefore should be recommended by nutritionists to be part of our diet.