2 2 azinobis

The following chemicals and reagents were purchased from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China): Folin–Ciocalteu reagent, 2,2-diphenyl-1-picrylhydrazyl (DPPH), aluminum nitrate, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), sodium carbonate, sodium nitrite, aluminum chloride, sodium hydroxide, ascorbic acid, gallic acid, rutin, and Trolox. Analytical grade ethanol was purchased from Sichuan Xilong Science Co., Ltd. (Chengdu, China). Pure water was prepared using a secondary reverse osmosis system (JYS-500L; Shanghai Juyuan Automation Technology Co., Ltd., Shanghai, China).

Dehulled quinoa cultivar ‘Jili 3’ was grown and harvested at Zhangjiakou Yuerwan Quinoa Planting Cooperative, which is located in Zhangjiakou City (115°36′ E, 415°27′ N), Hebei Province, China. The seeds were preserved in the dark at −20 °C under vacuum until germination. GABA, with a purity ≥ 99%, and 2,2-diphenyl1-picrylhydrazyl (DPPH) were purchased from Sigma-Aldrich (Shanghai, China). Threonine (99%), valine (99%), methionine (98%), isoleucine (98%), leucine (98%), phenylalanine (98%), lysine (98%), histidine (98%), arginine (98%), aspartate (98%), serine (98%), glutamate (98%), glycine (98%), alanine (98%), cysteine (98%), tyrosine (99%), proline (98%), gallic acid (99%), rutin (95%), saponin (98%), 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) (98%), sodium cholate (65%), sodium taurocholate (98%), sodium deoxycholate (98%), and sodium glycocholate (97%), as well as α-amylase (100,000 U/g), α-glucosidase (50,000 U/g), and pancreatic lipase (30,000 U/g), were obtained from Shanghai Yuanye Bio-Technology Co., Ltd. (Shanghai, China). Acetonitrile (chromatographically pure) was purchased from Macklin Biochemical Co. Ltd. (Shanghai, China). All other chemicals were analytical reagent grade.