Role in dough rheology of high molecular weight glutenin subunits of soft white winter and club wheats

The effect of high molecular weight glutenin subunit (HMW-GS) composition of seven soft white winter (SWW) and four club wheat cultivars from the Pacific Northwest region on dough rheology was investigated. All samples were harvested in 1988, 1990, and 1993 (in Walla Walla, WA). Three selected SWW and three club wheats were grown in 1990, in seven locations covering broad growing conditions. The SWW and club wheats grown under the same conditions showed similar protein content (11.70 and 11.65%, respectively) but distinctly different values of total area of HMW-GS (0.9-1.9 for SWW, and 0.7-1.3 for club wheat, excluding Hyak). The quality score of HMW-GS multiplied by area showed much better correlation with dough rheology (alveograph W: r = 0.905; mixograph mixing time: r = 0.743) and SDS sedimentation volume (r = 0.883) than for each of these parameters separately. The increase in protein content of SWW, (from 8.5 to 12.5%) and of club wheats (from 7.5 to 11%) resulting from growing conditions accompanies the increase of total area of HMW-GS, from 0.85 to 1.3 and from 0.7 to 0.95, respectively. However, that increase better matched the increase in protein content of SWW wheats (r = 0.662) than club wheats (r = 0.352). If the increase in protein content is substantial for the cultivars with high quality score HMW-GS, it might cause an increase of gluten strength as measured by dough rheology and SDS sedimentation value. The cultivar Hyak, containing the subunits 7+8 in Glu-IB locus and 5+10 in Glu-ID locus, is a good example of the latter. The club wheats (not Hyak), having a generally low quality score of HMW-GS, preserve unique properties of weak gluten, even with the increase of protein content.