Cereal Chem 52:57 - 69. | VIEW
Water-Soluble Pentosans of Wheat Flour. II. Characterization of Pentosans and Glycoproteins from Wheat Flour and Dough Mixed Under Various Conditions.
S. K. Patil, C. C. Tsen, and D. R. Lineback. Copyright 1975 by the American Association of Cereal Chemists, Inc.
Fractionation of water-soluble pentosans from doughs on a column of DEAE-cellulose indicated that treating the doughs with bromate and iodate reduced the amount of carbohydrate in fraction I, and increased the quantity of cabohydrate in fractions II to V (assumed to be glycoproteins) which contained most of the pentosan protein. In the absence of oxidizing agents, treatments that broke dough down during mixing showed an opposite effect. Pentosans from bromated and iodated dough mixed to optimum development (farinograph peak time) showed a marked increase in absorbance (280 nm.) of protein components obtained during gel filtration. Infrared (IR) amide II absorption, a secondary amide band of protein, shifted from 1,518 cm.-1 in pentosans extracted from flour to 1,538 cm.-1 in pentosans from doughs. The shift indicated a conformational change from the extended beta-configuration (1,518 cm-1) to the alpha-configuration of helical coil in the glycoprotein molecules. A short wavelength shift in protein absorbance (280.5 to 278 nm.) and in the IR amide II band, accompanied by a large increase in intensity, further indicated that the hydrogen-bonding capacity of pentosans was markedly increased when flour constituents were mixed into dough. The increase in ultraviolet absorbance probably resulted from aggregation of structures containing pentosans, proteins, and/or glycoproteins. Pentosans and glycoproteins apparently act as a bridge between protein and carbohydrate components. Oxidizing agents appear to play an important role in maintaining the bridge.