title: 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.
authors.affiliation: College of Food Science and Engineering, Northwest A&F University, Yangling, Shaanxi 712100, People's Republic of China.
authors.forename: Qing-Han
authors.initials: QH
authors.lastname: Gao
authors.forename: Chun-Sen
authors.initials: CS
authors.lastname: Wu
authors.forename: Min
authors.initials: M
authors.lastname: Wang
authors.forename: Bian-Na
authors.initials: BN
authors.lastname: Xu
authors.forename: Li-Juan
authors.initials: LJ
authors.lastname: Du
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002241:Carbohydrates / Q000032:analysis*; D002392:Catechin / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005511:Food Handling / Q000379:methods*; D005612:Freeze Drying; D062385:Hydroxybenzoates / Q000032:analysis; D008872:Microwaves; D010636:Phenols / Q000032:analysis*; D031957:Ziziphus / Q000737:chemistry*; D024502:alpha-Tocopherol / Q000032:analysis*; D019207:beta Carotene / Q000032:analysis*
chemical_list: D000975:Antioxidants; D002241:Carbohydrates; D062385:Hydroxybenzoates; D010636:Phenols; D019207:beta Carotene; C009091:protocatechuic acid; D002392:Catechin; D024502:alpha-Tocopherol