Fructose

The standards of narirutin, hesperidin, didymin, lycopene, β-carotene, fructose, glucose and sucrose were acquired from Yuanye Bio-Technology Co., Ltd (Shanghai, China). Phytoene and violaxanthin were purchased from CaroteNature (Lupsingen, Switzerland) and Sigma (St. Louis, MO, USA), respectively. ABTS⁺ (2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were purchased from Yuanye Bio-Technology Co., Ltd (Shanghai, China). High performance liquid chromatography purity solvents, including methyl tert-butyl ether (MTBE), methanol and hexane were obtained from Thermo Fisher Scientific (Leicestershire, UK). Other analytical grade chemicals, such as ethanol, hexane and sodium hydroxide were bought from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China).

Fresh apple was provided by Xuanwu Fruit Store, Nanjing, Jiangsu Province. Ethanol, acetonitrile, Folin-Ciocalteu reagent, organic acid standards (oxalate acid, pyruvic acid, malic acid, citric acid, succinic acid and lactic acid), phenolic acid standards (gallic acid, protocatechuic acid, catechin, procyanidin B₂, chlorogenic acid, hydroxybenzoic acid, caffeic acid, ferulic acid, rutin and quercetin), amino acid standards (Asp, Thr, Ser, Glu, Gly, Ala, Cys, Val, Met, Ile, Leu, Tyr, Phe, Lys, His, Arg, Pro) and sugar standards (fructose, sorbitol, glucose and sucrose) were all bought from Yuanye Biotechnology Co., Ltd (Shanghai, China).

2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, DPPH, 2,3,5-triphenyltetrazolium chloride (TPTZ), 6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), 3-nonanone as internal standard (IS), and ferrozine were purchased from Sigma Chemical Co. (St. Louis, MO, United States). Sorbitol, glucose, fructose, sucrose, formic acid, acetic acid, lactic acid, malic acid, citric acid, gallic acid (GA), protocatechualdehyde (PRO), (+)-catechin (CAT), chlorogenic acid (CHL), caffeic acid (CAF), syringic acid (SYR), epicatechin (EPI), p-coumaric acid (p-CUM), rutin (RUT), phlorizin (PRI), quercetin (QUE), and phloretin (PRE) were purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). All other reagents used were of analytical grade.

We obtained 3′,5′‐cyclic AMP and 5′‐HMF from Ziqibio Co., Ltd. (Shanghai, China), fructose, glucose, and sucrose were purchased from Shanghai Yuanye Bio‐Technology Co., Ltd. (Shanghai, China). Other reagents were of analytical grade. Acetonitrile and methanol were both of HPLC grade and purchased from Merck (Darmstadt, Germany). The dry jujubes were varieties of Ningyang jujube provided by the market (Taian, China).
The high‐performance liquid chromatography (HPLC) was performed on a LC‐20A system Shimadzu (Kyoto, Japan), equipped with diode array detector (SPD‐20A) and refractive index detector (RID‐10A). Data acquisitions were performed using Lab Solution software. IMS instrument (FlavourSpec^®) from Gesellschaft für Analytische Sensorsysteme mbH (G.A.S., Dortmund, Germany) equipped with a heated splitless injector and automatic sampler unit (CTC‐PAL, CTC Analytics AG, Zwingen, Switzerland) was utilized for instrumental aroma analysis. The IMS was equipped with a FS‐SE‐54‐CB‐1 column (15 m × 0.53 mm). IMS data were acquired and identified unknown compounds using GCxIMS Library Search software, and then analyzed by Laboratory Analytical Viewer supplied by G.A.S.

Glucose (Glu), Fructose (Fru), Mannose (Man), Galactose (Gal), Xylose (Xyl), Arabinose (Ara), Rhamnose (Rha), Fucose (Fuc), Galactose Uronic acid (GalUA), glucuronic acid (GlcUA), purity ≥ 98%, β-dextran (purity ≥ 80%), fructo oligosaccharide (purity ≥ 95%), xylan (purity ≥ 98%) and polygalacturonic acid (purity ≥ 90%) were purchased from Yuanye Biotechnology Co., Ltd. D-trehalose (purity ≥ 99%) was purchased from Shanghai McLean Biochemical Technology Co., Ltd. All of other chemicals and reagents were analytical grade.

All chemicals and reagents used were of analytical grade. Methanol and acetonitrile were purchased from Merck Co., Inc. (Darmstadt, Germany). Fructose, glucose, sucrose, and maltose standards were obtained from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China). 3,5-Dinitrosalicylic acid and indigo carmine were purchased from Shanghai Dibo Biotechnology Co., Ltd. (Shanghai, China). 4-nitrophenol and gallic acid were from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China). DPPH and TPTZ were purchased from Sigma-Aldrich (St. Louis, MI, USA). Proline and rutin were obtained from Beijing Bailingwei Technology Co., Ltd. (Beijing, China).