Modified Orcinol–Ferric Chloride Colorimetric Assay for Water‐Extractable Arabinoxylan in Wheat

Abstract

Cereal Chem. 94(3):576-580Arabinoxylans are an important quality component for which a simple and rapid analysis method useful for plant breeding needs to be developed. Bial's orcinol-ferric chloride colorimetric method was modified to allow simultaneous analysis of at least 24 samples in a single run and in small volumes to measure water-extractable arabinoxylan (WEAX) in wheat meal. The modified parameters were reduction to 6N HCl, increased concentrations of orcinol and 10% ferric chloride, and a total volume of 500 µL. The sample turbidity was reduced by rapid cooling in an ice water bath followed by addition of 500 µL of 95% ethanol postincubation. The WEAX results from this protocol were compared with GC/MS values. The wheat varieties of Alta Blanca, Eltan, and Hatton were overestimated by 4.3, 1.5, and 0.9%, respectively, whereas the varieties of Eden, Darwin, Finley, and Boundary were underestimated by 14.4, 8.9, 11.3, and 3.6%, respectively. The modified procedure is useful to determine a range of WEAX concentrations in wheat grains. † Corresponding