Carrez 2 solution

Glucose (G8270), lactose (17814), hydrogen peroxide (H1009), Carrez I solution (potassium hexacyanoferrate (II) trihydrate (60279)), Carrez II solution (zinc sulfate heptahydrate (31665)), magnesium chloride (M8266), triethylamine (TEA) hydrochloride (T1502), sodium citrate monobasic (71498), citric acid (27488), sodium phosphate monobasic (71496), sodium phosphate dibasic dihydrate (71645), potassium phosphate monobasic (795488), potassium phosphate dibasic (795496), iodonitrotetrazolium chloride (INT) (I8377), flavin adenine dinucleotide (F6625), Triton X‐100 (T9284), and imidazole (I202) were purchased from Sigma‐Aldrich, Arklow, Ireland. Vivinal GOS (Product # 598227; Lot # 704075) was kindly provided by Friesland Campina, Amersfoort, The Netherlands. Allolactose (O‐LAC6), 4‐nitrophenyl‐β‐d‐galactopyranoside (O‐PNPBGAL), Glucose oxidase/catalase mixture (E‐GOXCA), hexokinase/Glucose‐6‐phosphate dehydrogenase mixture (E‐HKGDH), 6‐phosphogluconate dehydrogenase (E‐PGDHEC), diaphorase (E‐DIAEC), EcLacZ (E‐ECBGAL), A. oryzae (E‐BGLAN) and MZ104 β‐galactosidase enzyme mixtures were obtained from Megazyme, Bray, Ireland. Note that following the current study, all components required to perform the low‐lactose (LOLAC) assay were made available as an assay kit from Megazyme (K‐LOLAC).

For the purpose of determinations, analytical purity reagents (analytical standards) designed for liquid chromatography were used: hydrochloric acid, formic acid, ethanol, and acetonitrile from Sigma Aldrich (Steinheim, Germany), and methanol from J.T. Baker Mallinckrodt Baker B.V. Holland. Buffers, ninhydrin, and a mixture of standards for amino acid identification were obtained from Sykam (Eresing, Germany), standardized for amino acid analyses in the physiological (native) range. Analytical standards of chlorogenic, caffeic, and ferulic acid for HPLC were obtained from Extrasynthese (Genay, France). Analytical standards D-(+)-glucose, D-(−)-fructose, D-(+)- sucrose, D-(+)- melezitose, D-(+)-turanose, D-(+)-trehalose, D-(+)-raffinose BioXtra, Ca, K, Mg, Fe, Cu, Mn, Zn, Al, Cd, and Pb were obtained from Sigma- Aldrich (Steinheim, Germany), and D-(+)-maltose standard was obtained from Toronto Research Chemicals. Carrez I solution, Carrez II solution (Sigma Aldrich, Steinheim, Germany), and deionised water from a deioniser from Hydrolab Polska HLP 5P were used.