Associations of starch gel hardness, granule size, waxy allelic expression, thermal pasting, milling quality, and kernel texture of 12 soft wheat cultivars

Starches were isolated from 12 soft wheat (Triticum aestivum L.) cultivars and were characterized for waxy (Wx) allelic expression, thermal pasting ch aracteristics, and starch granule size. Gels were produced from the thermal ly degraded starches and were evaluated using large deformation rheological measurements. Data were compared with cultivar kernel texture, milling cha racteristics, starch chemical analyses, and flour pasting characteristics. Larger flour yields were produced from cultivars that had larger starch gra nules. Flour yield also was correlated with lower amylose content and great er starch content. Harder starch gels were correlated with higher levels of amylose content and softer kernel texture. The cultivar Fillmore, which ha d a partial waxy mutation at the B locus, produced the highest peak pasting viscosity and the lowest gel hardness. Softer textured wheats had greater lipid-complexed amylose and starch phosphorus contents and had less total s tarch content. Among these wheats of the soft market class, softer textured wheats had larger starch granules and harder textured wheats had smaller s tarch granules. In part, this may explain why soft wheats vary in texture. The smaller granules have larger surface area available for noncovalent bon ding with the endosperm protein matrix and they also may pack more efficien tly, producing harder endosperm.