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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Cereal Crops Research » Research » Publications at this Location » Publication #255131
Title: Molecular weight distribution of proteins in hard red spring wheat: Relationship to quality parameters and intra-sample uniformity

Author
item Ohm, Jae-Bom
item Hareland, Gary
item SIMSEK, SENAY - North Dakota State University
item Seabourn, Bradford
item Maghirang, Elizabeth
item Dowell, Floyd

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/2010
Publication Date: 12/10/2010
Citation: Ohm, J., Hareland, G.A., Simsek, S., Seabourn, B.W., Maghirang, E.B., Dowell, F.E. 2010. Molecular weight distribution of proteins in hard red spring wheat: Relationship to quality parameters and intra-sample uniformity. Cereal Chemistry. 87(6):553–560.

Interpretive Summary: Proteins extracted from hard spring wheat grain were separated according to their size by size exclusion high performance liquid chromatography (SE-HPLC) to investigate their associations with wheat and breadmaking quality characteristics. Certain protein fractions were found to be related to wheat and breadmaking quality parameters. Since total protein content of wheat greatly affects wheat and breadmaking quality parameters, we investigated relationships of protein fractions separated by SE-HPLC with wheat and breadmaking parameters, specifically when they are statistically adjusted to the same protein level. From this research, we could identify protein fractions that affect wheat and breadmaking quality independently of quantity of total protein in wheat. Large size polymeric proteins that are insoluble in sodium dodecyl sulfate buffer solution were observed to have positive effect on percent vitreous kernel content and breadmaking parameters, including mix time and bread loaf volume. Protein fractions that primarily consisted of large size alcohol soluble proteins were observed to increase kernel hardness and optimum water absorption requirement for dough mixing. High proportion of main alcohol soluble gliadin fractions in total protein had negative effect on bread loaf volume but positive effect on kernel hardness and water absorption for breadmaking. Intra-sample uniformity in protein size distribution and kernel characteristics was estimated from three kernel subsamples which were separated according to single kernel protein content within individual wheat samples by a single-kernel near-infrared sorter. Wheat subsamples were significantly different in protein size distribution measured by SE-HPLC. Intra-sample uniformity in protein composition did not differ greatly among wheat samples.

Technical Abstract: Molecular weight distribution (MWD) of proteins extracted from hard spring wheat grain was analyzed by size exclusion HPLC to investigate associations with wheat and breadmaking quality characteristics. Certain protein fractions were found to be related to associations between wheat and breadmaking parameters specifically when effect of quantitative variation of protein on those parameters was statistically eliminated by partial correlation analysis. SDS unextractable high molecular weight polymeric proteins had positive partial correlations with percent vitreous kernel content and breadmaking parameters, including mix time and bread loaf volume. SDS extractable protein fractions that were eluted before the primary gliadin peak had positive partial correlations with kernel hardness and water absorption parameters. Proportion of main gliadin fractions in total protein had a negative partial correlation with bread loaf volume and positive correlations with kernel hardness and water absorption parameters. Intra-sample uniformity in protein MWD and kernel characteristics was estimated from three kernel subsamples which were separated according to single kernel protein content within individual wheat samples by a single-kernel near-infrared sorter. Wheat subsamples were significantly different in protein MWD. Intra-sample uniformity in protein MWD did not differ greatly among wheat samples.