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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCE HARD SPRING AND DURUM WHEAT QUALITY AND UTILIZATION

Location: Cereal Crops Research

Title: Sulfur, Protein Size Distribution, and Free Amino Acids in Flour Mill Streams and Their Relationship to Dough Rheology and Breadmaking Traits

Authors
item Liu, Ya -
item Ohm, Jae-Bom
item Hareland, Gary
item Wiersma, Jochum -
item Kaiser, Daniel -

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 14, 2010
Publication Date: March 31, 2011
Citation: Liu, Y., Ohm, J., Hareland, G.A., Wiersma, J., Kaiser, D. 2011. Sulfur, Protein Size Distribution, and Free Amino Acids in Flour Mill Streams and Their Relationship to Dough Rheology and Breadmaking Traits. Cereal Chemistry. 88(2):109-116.

Interpretive Summary: The aim of this study was to evaluate differences in sulfur content, protein size distribution, and free amino acids among flour mill streams (FMS) and their relationships to breadmaking characteristics. Information from this study would likely lead to more precise blending of FMS in commercial flour mills in order to meet customer specifications for high quality flour. FMS differed in nitrogen and sulfur contents. Break FMS had higher nitrogen and sulfur quantities than reduction FMS. The third break mill stream which had the highest protein and sulfur quantities among FMS had poor breadmaking quality showing low bread loaf volume partly due to high ash content. Sulfur quantity appeared important for quality evaluation of FMS. Sulfur quantity in FMS had greater associations with dough rheology and breadmaking properties than nitrogen quantity when influence of percent ash content on those parameters was removed. FMS also showed significant difference in size distribution of native proteins. The high molecular weight protein fraction which is not soluble in sodium dodecyl sulfated buffer solution was identified to affect dough rheological and breadmaking quality. Asparagine, which was a major amino acid in flour, was found at higher levels in the third break and third reduction FMS. FMS which had higher ratio of nitrogen to sulfur appeared to have higher asparagine concentration.

Technical Abstract: The aim of this study was to evaluate differences in sulfur content, protein size distribution, and free amino acids among flour mill streams (FMS) and their relationships to dough rheology and breadmaking traits. Information from this study would likely lead to more precise blending of FMS in commercial flour mills in order to meet customer specifications for high quality flour. Break FMS had higher nitrogen and sulfur quantities than reduction FMS. Specifically, the third break FMS had the highest protein and sulfur quantities among FMS but low bread loaf volume partly due to high ash content. Sulfur quantity appeared important for quality evaluation of FMS as it had greater correlations with dough rheology and breadmaking properties than nitrogen quantity when effect of percent ash content was removed. FMS also showed significant quantitative variation of high molecular weight polymeric proteins in SDS unextractable fraction, which was significantly associated with dough rheological and breadmaking traits. Asparagine, which was a major amino acid in flour, was found at higher levels in the third break and third reduction FMS. Ratio of nitrogen to sulfur was significantly related to asparagine concentration in FMS as indicated by a positive correlation coefficient of 0.73 (P<0.01) between them.

Last Modified: 4/17/2014
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