Ferrous sulfate

Frozen silver carp surimi was purchased from Fujian Anjing Foods Co., Ltd. (Xiamen, China), and kept at −20 °C until used. Black tea powder (caffeine removed) was purchased from Damin Foodstuff (Zhangzhou) Co., Ltd. (Zhangzhou, China). Tapioca starch, phosphate, salt and glutamine transaminase (TG enzyme) were commercially available.
1,1-diphenyl-2-picrylhydrazyl (DPPH) was purchased from Shanghai Yuanye Biotechnology Co., Ltd. (Shanghai, China); 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) was purchased from Beijing Solarbio Technology Co., Ltd. (Beijing, China); sodium dihydrogen phosphate, dibasic sodium phosphate, trichloroacetic acid, hydrogen peroxide, ferrous sulfate and potassium persulfate were of analytical grade and purchased from Xilong Chemical Co., Ltd. (Guangzhou, China). Absolute ethanol was purchased from Sinopharm Group Chemical Reagent Co., Ltd. (Shanghai, China); ferric chloride, potassium ferricyanide, and 3,5-Dinitrosalicylic acid were purchased from Shanghai Macklin Biochemical Technology Co., Ltd. (Shanghai, China).

Roswell Park Memorial Institute 1640 (RPMI 1640) medium was purchased from Gibco BRL (Germany). Sugar‐free RPMI 1640 medium was purchased from Procell (China). Penicillin‐streptomycin and Trypsin‐EDTA were purchased from Beyotime (China). L‐histidine and ascorbic acid were purchased from Sigma (St. Louis, USA). D‐glucose, MTX, and AMP chemical standards were purchased from Solarbio (China). 5‐MTHF and GMP chemical standards were purchased from Meilunbio (China) and TMRM (China), respectively. Ferrous sulfate was purchased from XiLONG Scientific (China). TBAB was purchased from J&K Scientific (China). Lower‐calorie jelly was purchased from ReadyDietech (China). HPLC grade acetonitrile and methanol were purchased from HiPureChem (China). All other chemicals were purchased from Sigma unless specifically mentioned.