Folin and Ciocalteu’s phenol reagent, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH radical), gallic acid, (±)-6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), methanol, and ethanol were purchased from Sigma–Aldrich (Milan, Italy). Edible-grade ascorbic acid, analyzed according to Ph.Eur.9.3, was purchased from Caelo Caesar and Loretz, GMBH (Hilden, Germany). Apples (Malus domestica) of variety Royal Gala (as indicated on the label), vinegar and salt were purchased in a local super-market.
Free full text: Click here