Granule size distribution of wheat starch is an important characteristic that can influence its chemical composition, which in turn may affect its functionality. The granule size distribution and chemical composition of soft wheat starches were characterized and compared and relationships among those properties were identified. Thirty‐four starch samples from 12 soft wheat cultivars grown in the eastern half of the United States were examined. Granule size distribution was characterized using a laser light‐scattering technique. Amylose and phospholipid contents were determined using colorimetric procedures. A clear trimodal distribution of granule sizes was shown by 26 out of 34 starch samples: small granules with diameters <2.8 μm, midsize granules with diameters of 2.8–9.9 μm, and large granules with diameters >9.9 μm. Volume% distribution of granules within the three size classes had ranges of 9.7–15.2% (small), 13.4–27.9% (medium), and 57.9–76.9% (large). Highly significant differences were seen among the cultivars for volume% of granules within the ranges of 9.9–18.5 μm and 18.5–42.8 μm. Cultivar specific surface area means also differed. The environment affected granule size distribution, with some cultivars exhibiting more variation than others. Pioneer 2555 was the least variable, whereas Pioneer 2550 and Geneva were the most variable cultivars. Mean total amylose (TAM), apparent amylose (AAM), and lysophospholipid (LPL) values varied significantly among cultivars. TAM was positively correlated with the volume% of granules of 9.9–18.5 μm. LPL was negatively correlated with mean starch granule diameter and positively correlated with specific surface area of granules, indicating smaller granules tended to have higher lipid contents. Results suggest that significant differences exist in granule size distribution of soft wheat starches and affect starch chemical composition. Data also suggest it is possible that lipid is preferentially associated with the biosynthesis of small starch granules.

Cereal Chem. 77(2):163-168Starches were isolated from 12 soft wheat (Triticum aestivum L.) cultivars and were characterized for waxy (Wx) allelic expression, thermal pasting characteristics, and starch granule size. Gels were produced from the thermally degraded starches and were evaluated using large deformation rheological measurements. Data were compared with cultivar kernel texture, milling characteristics, starch chemical analyses, and flour pasting characteristics. Larger flour yields were produced from cultivars that had larger starch granules. Flour yield also was correlated with lower amylose content and greater starch content. Harder starch gels were correlated with higher levels of amylose content and softer kernel texture.

Background and objectives: Soft red winter (SRW) wheat grain immediately after harvest and flour after milling were stored for 26 weeks and analyzed for comprehensive milling and baking quality characteristics at different time points to examine the consistency of the quality test results. Findings: Increases in falling number (FN) of grain during postharvest storage were observed for nine of ten varieties, in which FN ranged from 62 to 264 at 2 weeks after harvest and increased by 18-109 during storage for 21 weeks at 23°C. Wheat grain exhibited evident fluctuations in refined flour characteristics during the first 4 weeks of storage and then lesser changes with further storage.The storage time of grain did not significantly influence the milling yield, FN, and water SRC of refined flour. For refined flour during postmilling storage, storage time significantly affected all the flour characteristics, which showed evident fluctuations especially in the first 4 weeks of storage. The refined flour FNs of all four tested varieties increased from 373-405 to 377-417 during the first 8 weeks and then sharply to 427-474 with further storage for 26 weeks. Flour pH decreased slightly for the first 2 weeks after milling, was stable for the next 8 weeks, and then decreased again to 5.74-5.90 at 26 weeks. Small but steady decreases in both lactic acid SRC and SDS sedimentation volume were also observed for refined flour during storage. Postmilling storage induced relatively small changes in the solvent retention capacity and cookie diameter of flour. Conclusions: Postharvest and postmilling changes must be considered to achieve a reliable determination of the FN of wheat grain and flour, and pH, SDS sedimentation volume, and lactic SRC of flour. A storage time of 4 weeks would reduce the variation in wheat grain and flour quality test results, allowing reliable and reproducible evaluation. Significance and novelty: The FN of both wheat grain and flour significantly increases during postharvest and postmilling storages. The pH and protein strength of flour show small decreases during postmilling storage with even smaller changes in water retaining capacity and cookie-baking quality. K E Y W O R D S postharvest and postmilling storage, wheat quality ---