Dynamics of Nutrients in Jujube (Ziziphus jujuba Mill.) at Different Maturity Stages, Cultivars, and Locations in the Southwest United States

Abstract

Jujube (Ziziphus jujuba Mill.) is also called Chinese date. There are ∼100 jujube cultivars with limited commercial availability, and the majority of them have scant details in the United States. In this study, nutrient dynamics during fruit maturation of different jujube cultivars grown at Las Cruces, Los Lunas, and Alcalde, NM, were examined in 2018 and 2019. Cultivars varied by location and year, and included ‘Li’, ‘Lang’, ‘Sugarcane’, ‘September Late’, and ‘Sherwood’. Parameters tested were total phenolic content (TPC), proanthocyanidins (PAs), vitamin C, cyclic adenosine monophosphate (cAMP), and antioxidant capacity: 2,2-diphenylpicrylhydrazyl radical scavenging capacity and ferric reducing antioxidant potential (FRAP). Moisture, TPC, PAs, FRAP, and vitamin C content decreased with fruit maturity; however, the latter stage of fruit maturity showed an increase in cAMP. Compared with fruit at full-red maturity, creamy fruit had TPC, PA, FRAP, and vitamin C concentrations that were 1.0 to 1.8, 4.4 to 12.4, 1.9 to 2.6, and 0.1 to 1.3 times higher, respectively, depending on location (P < 0.05). From creamy to full-red maturity, cAMP increased by 0.9 to 4.5 times. At full-red maturity, estimated TPC in jujube fruit ranged from 10.6 to 16.8 mg gallic acid equivalent per gram dry weight (DW), whereas estimated PAs ranged from 1.8 to 5.3 mg PA B2/g DW. Jujube fruit at full-red maturity had a vitamin C content that ranged from 649.0 to 1153.3 mg/100 g DW. At full-red maturity, the concentration of cAMP ranged from 148.1 to 277.6 μg/g DW in Las Cruces samples.

Genotyping of Jujube (Ziziphus spp.) Germplasm in New Mexico and Southwestern Texas

“…trees in the wild with large fruit and good flavor were domesticated in the past, and consequently, the current jujube cultivar that we know today originated from these ancient selections [9]. Due to its high vitamin C, cyclic AMP, phenolics, flavonoids, natural colorant properties, and mineral content (particularly potassium and iron), as well as biologically active compounds, Chinese jujube is used both as a fruit and herbal medicine for its dry fruit and seeds [10][11][12][13][14][15][16]. Due to its higher tolerance for drought and salinity and lower demand for irrigation and fertilization, jujube is considered an important cash crop for arid and semi-arid regions [3,17].…”

Jujube Fruit Metabolomic Profiles Reveal Cultivar Differences and Function as Cultivar Fingerprints

“…Our results indicate jujube cultivars vary significantly in their metabolomic profiles, including secondary metabolites, which constitute one of the major groups of differential metabolites among all pairwise cultivar comparisons in our study. Among the eleven cultivars tested, there were two groups with identical DNA single nucleotide polymorphism (SNP) sequences: Li/Shanxi Li and Jinsi (2/3)/JKW [ 49 ]. The metabolic similarity of Li/Shanxi Li and Jinsi (2/3)/JKW in their fruit metabolomes agrees with the DNA genotyping results of both cultivar pairs.…”

“…So, Li, Linyi Li, and Shanxi Li are synonyms of one cultivar or mutations. Similarly, JS and JKW also had identical SNP sequences in a jujube genotyping study [ 49 ]. The similarity of their metabolic profiles support their similar genotypes, and both cultivars are closely related cultivars or the same cultivar.…”

“…Jujube has been described as a super fruit due to its high contents of carbohydrates such as glucose, fructose, and sucrose; vitamins such as vitamin C; phenolics such as 4-hydroxybenzoic acid glycosides; nucleotides such as cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP); minerals; flavonoids such as catechin and quercetin glycosides; and amino acids such as arginine, proline, glutamic acids, and asparagine [ 10 , 11 ]. For example, the vitamin C content of the jujube fruit ranges from 200 to 600 mg/100 g fresh weight and its cAMP content was the highest among 200 fruit species tested in 1980 [ 12 , 13 , 14 , 15 ]. In addition, jujube is the source of many natural products with medicinal potential and application in herbal medicine.…”

“…Jujube has been studied by untargeted metabolomics in terms of the dry fruit nutrient composition [ 38 ], nutrient dynamics during fruit development, maturation of different cultivars [ 39 , 40 , 41 , 42 ], types of flavonoids, the amount of bitterness [ 42 , 43 ], vitamin C [ 44 ], free amino acids, polyphenols, sugars [ 45 ], and the metabolite differences between different leaf stages [ 46 ] and between wild and domesticated jujube [ 47 ]. NMSU had replicated jujube cultivar trials at three sites across New Mexico [ 8 , 9 ], which provides an opportunity to evaluate different Ziziphus jujuba cultivars in terms of fresh fruit metabolomes within the U.S. We have studied several nutritional metabolites from our jujube cultivars [ 14 , 15 ], but an untargeted metabolomic analysis of these jujube cultivars is lacking. The objectives of this study were, therefore, to examine the global metabolite profiles of mature fruits derived from different jujube cultivars at three cultivar trial sites in New Mexico and evaluate the cultivar-specific effects on jujube metabolomes by liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis.…”