Aluminum chloride

Tartary buckwheat seeds (Hefeng No. 1) were cultivated in Datong, Shanxi Province, China, and were acquired from Beijing Green Valley Sprout Co., Ltd. (Beijing, China). Rutin, gallic acid, and γ-Amino butyric acid standard were purchased from Shanghai solarbio Bioscience & Technology Co., Ltd. (Shanghai, China). The analytical grade chemicals, such as Folin-Ciocalteu reagent, gallic acid (GA), sodium carbonate, sodium hypochlorite, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, phosphoric acid, glucose anhydrous, aluminum chloride, potassium acetate, o-phthalaldehyde, copper sulfate, potassium sulfate, sulfuric acid, boric acid, ethanol, ethyl acetate, hydrochloric acid, trichloroacetic acid, sodium acetate, phenol, potassium persulfate, sodium hydroxide, and aluminum chloride were purchased from Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China). In addition, 2,2-diphenyl picryl hydrazyl (DPPH), acetone, and methanol (HPLC grade) were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Total antioxidant capacity (T-AOC) kit was purchased from Nanjing Jiancheng Bioengineering Institute (Nanjing, China).

FO membrane modules with an active layer at the lumen side of hollow fibers were purchased from Aromatec, Singapore. Polytetrafluoroethylene (PTFE) membranes (Zhongke Bidu New Membrane Technology Co., Ltd., Nanjing, China) with a nominal pore size of 0.1 μm were used for the VMD process. Commercially available apple juice (Huiyuan Group Co., Ltd., Beijing, China, TSS of 10.2 °Brix) was used as the feed solution (FS). Sodium chloride (NaCl) GR 99.8%, anhydrous sodium sulfite (SSF) AR 98%, sodium metabisulfite (SMB) AR 96%, sodium benzoate (SB) AR 99.5%, sodium diacetate (SDA) 99%, potassium sorbate (Sorb-K) 99% and sodium lactate (L-NaLa) (60% in water) were acquired from Macklin Biochemical Technology Co., Ltd. (Shanghai, China). to prepare the DS using ultrapure water. Gllic acid 99%, sodium carbonate anhydrous 99.9%, Folin–Ciocalteu’s phenol reagent 2 M, (+)-Catechin AR, aluminum chloride 99.99% and 2,2-diphenyl-1-picryhydrazyl (DPPH) HPLC 98.5% were also purchased from Macklin Biochemical Technology Co., Ltd. (Shanghai, China). D(+)-Glucose monohydrate was acquired from Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Sodium hydroxide AR 98%, sulfuric acid AR 95~98%, phenol GR 99.5%, sodium nitrite GR 99% and L(+)-Ascorbic acid AR 99.7% were obtained from Kelong Chemical Co., Ltd. (Chengdu, China).