Cereal Chem 68:122-130 | VIEW
Characterization of Wheat Protein Fractions Differing in Contributions to Breadmaking Quality.
F. MacRitchie, D. D. Kasarda, and D. D. Kuzmicky. Copyright 1991 by the American Association of Cereal Chemists, Inc.
Protein fractions from six wheat cultivars, three of good quality and three of poor quality, were prepared by fractional extraction of gluten with dilute hydrochloric acid, and the relationship between breadmaking functionality and protein composition was investigated. Functionality was assessed by adding fractions to a base (reference) flour at a level of 1% (protein to flour weight) and measuring mixograph peak development times and loaf volumes in an optimized baking test. Protein composition was measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis under reducing and nonreducing conditions, followed by densitometry of the stained patterns. The pattern areas of reduced fractions, which corresponded to total proteins, were divided into subareas representative of five main protein classes: high molecular weight glutenin subunits; omega-gliadins; low molecular weight glutenin subunits; alpha-, beta-, and gamma- gliadins; and albumins plus globulins. Also, the proportion of glutenin in each fraction was estimated for some cultivars as the difference between the total area under the densitometer tracing of the pattern of a fraction reduced (total proteins) and the total area under the densitometer tracing of the pattern of the same fraction unreduced (from which essentially only monomeric proteins enter the gel). The proportion of high molecular weight glutenin subunits in the parent glutens increased in accordance with dough strength and, with one exception, loaf volume. As the fraction number increased, the proportion of glutenins generally paralleled the increases observed in dough development time and loaf volume, except for some of the later fractions.