Effect of Drying of Jujubes (Ziziphus jujuba Mill.) on the Contents of Sugars, Organic Acids, α-Tocopherol, β-Carotene, and Phenolic Compounds

Abstract

This study investigated the changes in sugars, organic acids, α-tocopherol, β-carotene, phenolic profiles, total phenolic content (TPC), and antioxidant capacity of jujube fruits after four drying treatments (sun-, oven-, microwave- and freeze-drying). Sugar, organic acid, phenolic compounds, α-tocopherol, and β-carotene were qualitatived and quantitatived by high-performance liquid chromatography. The TPC and antioxidant activity of jujube samples were evaluated using the Folin-Ciocalteau method and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical scavenging activity, respectively. Freeze-drying resulted in jujubes with higher antioxidant activity and was also a good choice for the preparation of β-carotene from jujubes for the food industry. Microwave-dried jujubes had a higher content of protocatechuic acid, catechin, and epicatechin and maintained the same antioxidant capacity with the freeze-dried jujubes. The combination of microwave- and freeze-drying may be an efficient alternative with shorter processing time and, consequently, less impact on the nutritional value of the jujube.

Effect of Sun, Oven and Freeze-Drying on Anthocyanins, Phenolic Compounds and Antioxidant Activity of Black Grape (Ekşikara) (Vitis vinifera L.)

“…Previous studies on the impact of different drying techniques on the antioxidant activity of fruit confirm our results (Gao et al, 2012;Chong et al, 2013;Annegowda et al, 2014). Significant reductions in the antioxidant activity of jujube fruit in ABTS from oven-and sun-drying methods were reported in a previous study (Gao et al, 2012).…”

“…Significant reductions in the antioxidant activity of jujube fruit in ABTS from oven-and sun-drying methods were reported in a previous study (Gao et al, 2012). Chong et al (2013) reported that the heat pump, heat pump vacuummicrowave, hot air vacuum-microwave and hot air-cold air drying methods significantly reduced the DPPH antioxidant activities of apple, papaya and mango.…”

Functional components in Zizyphus with emphasis on polysaccharides

“…San and Yildirim (2010) analyzed four varieties of four jujube fruits, and b-carotene was present at a level from 7 to 35 mg/100 g based on fresh weight, whereas the amount of carotenes was from 4.12 to 5.98 mg/100 g of dry weight as reported by Guil-Guerrero et al (2004). It was also shown that a much higher amount of b-carotene (15.6 mg/100 g) could be retained by freeze-drying (Gao et al 2012). …”

Variation of Bioactive Compounds and Antioxidant Activity of Jujube (Ziziphus jujuba) Fruits at Different Stages of Ripening

“…The same trend was registered for malic, lactic and tartaric acid. Oxalic acid was recorded in white maturity of fruits in Gao et al (2012) showed that ascorbic acid values were positively correlated with hardness in ten promising jujubes. The highest value in ascorbic acid of jujube fruits was recorded in harvested fruit at fully mature stage (637 mg/100g FW), by Moradinezhad et al (2016).…”