Jujube Cultivar Vitamin C Profile and Nutrient Dynamics during Maturation

Abstract

Vitamin C profiles of 46 jujube cultivars were assessed from 2012 to 2015, and fruit nutrient dynamics of 10 cultivars during maturation were examined from 25 Aug. to 7 Oct. 2014 at 2-week intervals at New Mexico State University’s Alcalde Sustainable Agriculture Science Center and Los Lunas Agricultural Science Center. This is the first report in the United States profiling Vitamin C in jujube cultivars. The vitamin C content of mature fruit of 45 (of 46) cultivars ranged from 225 to 530 mg/100 g fresh weight (FW) plus ‘Youzao’ having the highest content of 820 mg/100 g FW at early mature stage. In general, drying cultivars had higher vitamin C content than fresh-eating cultivars whereas ‘Jinsi’ series (multipurpose) had relatively higher vitamin C content than others (>400 mg/100 g FW). Fruit vitamin C and moisture content decreased significantly during the maturation process. The average vitamin C contents of nine cultivars at Alcalde decreased more than 40% based on FW from 25 Aug. to 7 Oct. To maximize the vitamin C benefit, the ideal stage to consume fresh-eating cultivars is the creamy stage. Titratable acidity and soluble solids increased significantly during maturation. In mature jujubes, the titratable acidity and soluble solids ranged between 0.27% to 0.46% and 27.2% to 33.7%, respectively. Glucose, fructose, and sucrose content also rose significantly during ripening. Mature fruits contained 31–82 mg/g FW glucose, 32–101 mg/g FW fructose, and 53–159 mg/g FW sucrose among the cultivars tested. Based on sucrose contents, cultivars can be divided into two groups, “high-sucrose” (more sucrose than glucose or fructose) and “low-sucrose” (less sucrose than glucose or fructose). ‘Dagua’, ‘Honeyjar’, ‘Lang’, ‘Li’, ‘Maya’, ‘Sugarcane’, and ‘Sherwood’ belong to the “high-sucrose” group. Total phenolic content and 2,2-diphenyl-1-picrylhydrazyl (DPPH)-reducing capacity in fruit decreased during maturation, and the total phenolic content of mature jujube was 12–16 mg gallic acid equivalent (GAE)/g dry weight (DW). For mature fruit, ‘Li’ and ‘Li-2’ had the highest DPPH-scavenging efficiency whereas ‘Sugarcane’, ‘So’, and ‘Lang’ had the lowest at Alcalde, NM.