Variation in protein composition of wheat flour and its relationship to dough mixing behaviour

Changes in extractability, amount and size distribution of polymeric proteins in the gluten of doughs during mixing were investigated. Ultracentrifugation was used as a non-destructive method to separate the gluten from the dough. Doughs prepared from commercial flour mixtures of different gluten strengths and mixed for varying periods, were analysed. Proteins were detected using RP- and SE-HPLC. The percentages of large unextractable polymeric protein (UPP), total UPP and large unextractable monomeric protein (UMP) were higher in the gluten phases of all flours at minimum and optimum mixing, compared to the flours. After overmixing, the percentages of large UPP, total UPP and large UMP in the gluten phases of the dough decreased to lower levels than in the flours. Differences in percentages of large UPP, total UPP and large UMP between gluten phases of different flours and mixing times originated from the genetic composition of flour proteins. The extractability of the glutenins in the flours reflected the quality of the specific flour. The protein extractability, especially of gliadins, was different in the gluten phase compared to in the flour. Ionic interactions seem to be important forces in the dough. (C) 2004 Elsevier Ltd. All rights reserved.