Effect of drying of jujubes ( Ziziphus jujuba Mill.) on the contents of sugars, organic acids, α-tocopherol, β-carotene, and phenolic compounds

J Agric Food Chem. 2012 Sep 26;60(38):9642-8. doi: 10.1021/jf3026524. Epub 2012 Sep 17.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antioxidants / analysis*
  • Carbohydrates / analysis*
  • Catechin / analysis
  • Chromatography, High Pressure Liquid
  • Food Handling / methods*
  • Freeze Drying
  • Hydroxybenzoates / analysis
  • Microwaves
  • Phenols / analysis*
  • Ziziphus / chemistry*
  • alpha-Tocopherol / analysis*
  • beta Carotene / analysis*

Substances

  • Antioxidants
  • Carbohydrates
  • Hydroxybenzoates
  • Phenols
  • beta Carotene
  • protocatechuic acid
  • Catechin
  • alpha-Tocopherol