Submitted to: Journal of Cereal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 10, 2008
Publication Date: January 1, 2009
Citation: Park, S., Wilson, J.D., Seabourn, B.W. 2009. Starch granule size distribution of hard red winter and hard red spring wheat: Its effects on mixing and breadmaking quality. Journal of Cereal Science. 49:98-105. Interpretive Summary: It is generally accepted that two distinct sizes of wheat starch granules, large A-type granules (generally larger than 10 'm in diameter) and small B-type granules (smaller than 10 'm in diameter), are existed, and they have different physical, chemical, and functional properties. However, there are limited researches have been conducted to find relationship of starch granules size distribution and final product quality. The objectives of this study were to investigate the in-depth starch granule size distribution of hard red winter (HRW) and hard red spring (HRS) wheats, and their relationships to wheat, flour, and breadmaking properties. We found that there were significant differences in the granule size distribution between HRW and HRS wheats. The B-type granules occupied volumes in the range 28.5 - 49.1% (mean 39.9%) for HRW wheat while HRS wheat B-type granules occupied volumes in the range 37.1- 56.2% (mean 47.3%). Numerous wheat and flour quality traits were also shown to be related to starch granule size distributions. The volume and size of B-type granules tended to decrease when protein content increased. Crumb grain of bread seemed to be affected by starch granule size distribution, showing an optimum volume ratio of A- and B-type granules. In addition, the optimum ratio appeared to be variable depending on the protein content of flour to produce bread with better crumb grain.
Technical Abstract: Starch was isolated from 98 hard red winter (HRW) wheat and 99 hard red spring (HRS) wheat. Granule size/volume distributions of the isolated starches were analyzed using a laser diffraction particle size analyzer. There were significant differences in the size distribution between HRW and HRS wheats. The B-type granules (< 10 µm in diameter) occupied volumes in the range 28.5 - 49.1% (mean 39.9%) for HRW wheat while HRS wheat B-type granules occupied volumes in the range 37.1- 56.2% (mean 47.3%). The mean granule sizes of the distribution peaks less than 10 µm in diameter also showed a significant difference (HRW, 4.32 vs. HRS, 4.49 µm), but the mean sizes of the distribution peaks larger than 10 µm were not significantly different (21.54 vs. 21.47 µm). Numerous wheat and flour quality traits also showed significant correlation to starch granule size distributions. Most notably, protein content was inversely correlated with parameters of B-type granules. Crumb grain score seemed to be affected by starch granule size distribution, showing significant inverse correlations with B-type granules. Furthermore, the linear correlations were improved when the ratio of B-type granules to protein content was used, and in addition, polynomial relation was applied. There seemed to an optimum range of B-type granules for different protein content flour to produce bread with better crumb grain.