Uniqueness of club wheat vs. soft white wheat.

摘要

The Pacific Northwest (PNW) is well recognized for its soft white wheat production and it is the only area where club wheat is grown. Overseas and domestic users of club and soft white wheats highly appreciate properties of both classes of wheat, especially the unique end product quality of club wheat. Broad growing conditions (climatic and soil) of the PNW, as well as new varieties, have resulted in undesirable changes in both classes of wheat in recent years (e.g., increased hardness, protein content and starch damage). These changes in wheat quality are of concern to users of both classes of wheat. Therefore, several approaches were applied to address quality characteristics within each class of wheat and differences in quality between club and soft white winter wheats based on: (1) grain characteristics; (2) milling performance; (3) protein quality; (4) dough rheology; and (5) starch properties.;Club wheat was significantly lower in test weight and 1000 kernel weight than SWW wheat. In spite of this, club wheat exhibited better milling performance than SWW wheat. There was no difference, on average, in protein (and ash) content between both classes of wheat through years and locations. Consistently, club wheat was significantly lower in sodium dodecyl sulfate sedimentation volume and significantly higher in urea dispersibility than SWW wheat. SWW wheat was significantly higher in alveograph parameters and had longer mixograph mixing time than club wheat, which indicates stronger gluten strength. These distinctly different features of gluten proteins in club wheat resulted from the low score and amount of high molecular weight glutenin subunits (HMW-GS). As the result of the present study, cv. Hyak was eliminated from the class of club wheat since it does not show the unique pattern of HMW-GS. Both classes of wheat flour had comparable levels of starch content, starch damage and amylograph flour peak viscosity, while differing significantly in peak viscosity of isolated starches.;The results based on a large quantity of material grown for three years in seven locations showed that club wheat exhibited better stability in grain characteristics, milling performance, protein quality and starch properties than SWW wheat.