Folin ciocalteu s phenol reagent 2 n

Dialysis tubing cellulose membrane (flat width 4.3 cm), (Sigma D9527, Germany). Folin ciocalteu’s phenol reagent (2 N) (Sigma-Aldrich F9252, USA) was used to estimate protein content. Bovine serum albumin (Sigma A2153, USA) was used to prepare the standard curve for calculating protein content. Sephadex G-200 (Pharmacia 17-0080-01, Sweden) was used for gel filtration chromatography. Dinitrosalicylic acid (Sigma D0550, USA) was used as a reagent to determine exo-PG activity. Polygalacturonic acid from orange (Sigma P3889, Spain) was used as a substrate to determine exo-PG activity. D-Galacturonic acid (Fluka 48280, Slovakia) was used to prepare the standard curve for calculating reducing sugar.

Ethanol, mEthanol (HPLC grade), Trolox^®, and Folin–Ciocalteu’s Phenol Reagent 2N were purchased by Sigma-Aldrich (Saint-Quentin Fallavier, France). Chlorogenic acid (5-caffeoylquinic acid: 5-CQA), neo-chlorogenic acid (3-caffeoylquinic acid: 3-CQA), and krypto-chlorogenic acid (4-caffeoylquinic acid: 4-CQA) were supplied by Sigma (Sigma Chemical Co., St. Louis, MO, USA). Anhydrous sodium carbonate was purchased from Fisher Scientific Company (Illkirch-Graffenstaden, France). 2,2-Azotis-(2-amidinopropane)-dilhydrochloride (AAPH), fluorescein (FL; 3′,6′-dihydroxyspiro[isobenzofuran-1[3H],9′[9H]-xanthen]-3-one or fluorescein sodium salt) were supplied by Wako Chemicals USA, Inc. (Richmond, VA, USA).
All solvents, reagents, and standards used in this work were HPLC grades (purity P 99%). All reagents and standard solutions were prepared with water purified on Veolia Water Systems™ (Veolia, Vendin-le-Vieil, France) S15 reverse osmosis apparatus.

The number of phenolic –OH groups remaining in QCT NPs after synthesis was determined by the Folin–Ciocalteu method as previously described with some modification [30 (link)]. Briefly, QCT and QCT NPs were prepared as 1 mg/mL stock solutions in DMSO. QCT dilutions were prepared in the range 5–100 μg/mL, and 250 μL of each concentration were transferred to a 15-mL conical tube. Fifty microliters of each NP stock solution was diluted to 250 μL with DMSO and placed in a 15-mL conical tube. One milliliter of Folin–Ciocalteu’s phenol reagent (2 N, Sigma-Aldrich) diluted 10 times with ultrapure water was added to each conical tube, followed by the addition of 1 mL sodium bicarbonate (10% w/v in ultrapure water). The samples were incubated at RT in the dark for 30 min, and then the UV absorbance was measured at 765 nm using a solution composed of 1 mL phenol reagent, 1 mL sodium bicarbonate, and 250 μL DMSO as blank. QCT dilutions were used to construct a calibration curve of absorbance at 765 nm versus concentration, from which the total phenol content in QCT NPs was determined and results were expressed as μg QCT equivalents per mg NP. The experiment was performed in triplicate.

Blueberry pomace powder prepared by freeze-drying blueberry wine pomace (from Vaccinium angustifolium, lowbush blueberry) was kindly provided by Nova Agri Inc. (Centreville, NS, Canada) and stored at −30 °C prior to use. All the chemicals were of analytical reagent grade. Sodium benzoate and hydrochloric acid were obtained from Sigma Scientific (Oakville, ON, Canada). Ethanol, methanol and formic acid of HPLC grade were purchased from Caledon Laboratories (Georgetown, ON, Canada). Folin–Ciocalteu’s phenol reagent (2 N), sodium carbonate, sodium nitrite, aluminium chloride, gallic acid (GA), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were purchased from Sigma-Aldrich Chemical Company (St Louis, MO, USA). (+)-Catechin and Folin–Ciocalteu reagent were purchased from Fluka (Milwaukee, WI, USA). Anthocyanin standards in the form of anthocyanidins (cyanidin chloride, dephinidin chloride, malvidin chloride, pelargonidin chloride, peonidin chloride and petunidin chloride) and dimethyl sulfoxide were obtained from Indofine Chemical Company Inc. (Somerville, NJ, USA).