Physicochemical and biochemical variations of jujube (Ziziphus jujuba Mill.) populations: A comparison of Iranian and imported types

Abstract

Jujube (Ziziphus jujuba Mill.) is a strategic plant that can be cultivated compatibly in many regions of Iran. Despite their long history in medicinal and nutritional applications, Iranian jujubes have been the subject of few studies so far. In the present study, we analyzed several physicochemical characteristics, nutritional values and antioxidant activity in eight Iranian jujube populations and in an imported jujube (known as the Belarusian jujube in Iran). The most important factors that were measured in the fruits included total flavonoid content, phenolic compounds, antioxidant activity and polyphenol compounds which were identified by HPLC. The compounds were, namely, catechin, gallic acid and vanillic acid, as well as protein content, along with several nutrient elements (i.e. P, K, Fe, Cu, Zn). The measurements also covered color index (L, a*, b*, Hue angle, Chroma) and physical properties. The results of the present study showed that most of the measured parameters varied significantly among the jujube populations. The highest flavonoid content (3.064 mg quercetin equivalent/g), total phenolic compounds (32.902 mg gallic acid equivalent/g) and antioxidant activity (90.61%) were recorded in Abiz, an Iranian population. Esfeden and Abiz populations had the highest amounts of catechin (14.160 and 13.398 mg/g) and gallic acid (1.027 and 0.285 mg/g), respectively. The highest (3.38%) and lowest (2.31%) protein contents were recorded in Esfeden and Abiz populations, respectively. The imported types of jujube had the largest fruit diameter and length (25.74 and 34.83 mm, respectively). In sum, Abiz and Zirkuh populations had the best quality in terms of biochemical properties and, thus, they can be used potentially in industries or in plant breeding programs.