Phenolic, alpha-tocopherol, beta-carotene and fatty acid composition of four promising jujube (Ziziphus jujuba Miller) selections

The phenolic, alpha-tocopherol, beta-carotene and fatty acid composition of four jujube selections were investigated in this study. Phenolic compounds, alpha-tocopherol and beta-carotene were analyzed with an HPLC device equipped with a diode array detector, and the fatty acid methyl esters were analyzed with QP 5050 GC/MS equipped with a CP-Wax 52 CB column. Among the jujube selections, considerable differences in phenolic and fatty acid contents were found. Catechin, caffeic acid, p-coumaric acid, ferulic acid, rutin, apigenin-7-glucoside, eriodictyol, quercetin, p-hydroxybenzoic acid, chlorogenic acid and syringic acid were isolated from leaves. Rutin content was very high in the leaves of all the jujube selections, ranging from 269.0 to 367.90 mg/100 g, followed by apigenin-7-glucoside (22.90–49.38 mg/100 g) and eriodictyol (5.06–6.27 mg/100 g). Seven phenolic compounds, catechin, caffeic acid, epicatechin, ferulic acid, rutin, p-hydroxybenzoic acid and chlorogenic acid, were isolated from fruits of jujube selections. Catechin level ranged from 2.46 to 3.74 mg/100 g, and rutin level ranged from 0.88 to 3.60 mg/100 g for fruits. Predominant phenolics were rutin and apigenin-7-glucoside for leaves, and catechin and rutin for fruits. Jujube leaves contained higher amounts of phenolic compounds than jujube fruits. Alpha-tocopherol was only detected in fruits of selections 20-Ç-22 and 20-Ç-52 (0.04 and 0.07 mg/100 g, respectively). Beta-carotene was significantly higher in 20-Ç-22 (35.0 μg/100 g) than in the other selections. Lipid content of the fresh fruits ranged from 0.06% to 0.10% among the four jujube selections. The predominant fatty acids in all jujube selections were oleic acid, linoleic acid, palmitic acid and palmitoleic acid. Unsaturated fatty acids comprised 68.54–72.44% of the total fat in jujube fruit.