Integrated total dietary fiber assay kit

Banana (var. Cavendish, produced by Costanza Organic Bananas, Ecuador) and red beetroot (grown at a local agricultural farm) were purchased in a local store. Hydrochloric acid (37%), bromcresol green and methyl red indicators, boric acid and Folin-Ciocalteu's reagent were supplied from Kemika (Zagreb, Croatia). Kjeldahl tablets were purchased from CarlRoth (Karsruhe, Germany). An integrated total dietary fiber assay kit was purchased from Megazyme (Wicklow, Ireland). Dopamine hydrochloride, (S)-6-Methoxy-2,5,7,8-tetramethylchromane-2-carboxylic acid (Trolox), 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2 -Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), gallic acid, neutral red and dichlorofluorescein diacetate (DCFDA) were purchased from Sigma-Aldrich (St. Louis, USA). Standards of D-glucose, D-fructose and sucrose were purchased from Fluka (Taufkirchen, Germany). Methanol was supplied from Panreac (Barcelona, Spain) and ethanol (96%), glacial acetic acid (85%) and acetonitrile from Carlo Erba (Val de Reuil, France). All chemicals used for experimental procedures were of analytical grade.