Progress 10/01/09 to 09/30/12
Outputs
Target Audience: Audiences will be readers of the scientific literature where results were reported in 2012. Starting in 2013 a short course was initiated for cereal science and rheology. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?
Nothing Reported
How have the results been disseminated to communities of interest? Mainly in journal articles and scientific meetings, What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The main expected outcome is a rapid test for the rheological properties of hydrated wheat. Current rheological tests based on expensive rheometers are limited to the laboratory and are time consuming, which limits the number of samples that can be checked. The essence of wheat for the end user is its blend of viscosity (or flow) and elasticity. Up until now it has been very difficult to capture this blend with a simple rapid test that can be used in the field as well as the laboratory. Despite the great variety of physicochemical and rheological tests available for measuring wheat flour, dough and gluten quality, the US wheat marketing system still relies primarily on wheat kernel hardness and growing season to categorize cultivars. To better understand and differentiate wheat cultivars of the same class, the tensile strength, and stress-relaxation behavior of gluten from 15 wheat cultivars was measured and compared to other available physicochemical parameters, including but not limited to protein content, glutenin macropolymer content (GMP) and bread loaf volume . In addition, a novel gluten compression-relaxation (Gluten CORE) instrument was used to measure the degree of elastic recovery of gluten for 15 common US wheat cultivars. Gluten strength ranged from 0.04 to 0.43 N at 500% extension, while the degree of recovery ranged from 5 to 78 %. Measuring gluten strength clearly differentiated cultivars within a wheat class; nonetheless it was not a good predictor of baking quality on its own in terms of bread volume. Gluten strength was highly correlated with mixograph mixing times (r=0.879) and degree of recovery (r=0.855), suggesting that dough development time was influenced by gluten strength and that the CORE instrument was a suitable alternative to tensile testing, since it is less time intensive and less laborious to use. Development of cereal products that utilize β-glucan-containing oat ingredients alongside gluten-containing wheat ingredients could allow for the combination of β-glucan's health benefits with wheat gluten’s functional benefits. Cereal products, however, are complicated systems, and understanding interactions between components is important for a successful product development process. The purpose of this study was to specifically investigate the interaction of wheat gluten and oat β-glucans, in terms of gluten elasticity. Wheat gluten was hydrated and developed in the presence of variable doses of three commercially available oat bran materials, containing 5%, 27%, and 70% β-glucan by weight. Replicate control and dosed gluten samples were then evaluated with a uniaxial compression-recovery assay, and by moisture analysis. Dose-response curves for all three treatment materials showed similar trends. Recovery Index, a measure of the elastic component of gluten’s viscoelasticity, increased with increasing dose. Half-Recovery Time, a measure of how long samples took to recover half their ultimate recovery distance, decreased with increasing dose. Moisture Content decreased with increasing dose for all materials. The observed changes in Recovery Index, Half-Recovery Time, and Moisture Content are hypothesized to be caused by interactions between gluten and β-glucan. Specifically, it is hypothesized that β-glucans decrease gluten hydration by acting as alternative hydrogen-bonding partners to water in hydrophilic portions of the gluten network, which in turn results in a less plasticized, more elastic material.
Publications
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: The major output for this project is the development of a commercial prototype instrument for determining the elastic properties of wheat gluten and dough. The instrument was the result of a multi-year collaborative study by Cornell, Oklahoma State, USDA-GIPSA and Perten Instruments Sweden, who developed the actual instrument. The instrument represents an innovation in cereal science by isolating the elastic properties of gluten. Results have been disseminated by presentation at the Wheat Quality Conference IV (2009), publication and communications with US Wheat Associates. It is expected that additional units will be made available to major wheat quality centers in the US in the coming year. PARTICIPANTS: Rangan Chinnaswamy, National Grain Center, USDA-GIPSA Patricia Rayas-Duarte, Robert M Kerr & Agricultural Products Center; Biochemistry and Molecular Biology Department, Oklahoma State Univ, Stillwater, OK. Bo Allvin, Perten Instruments, Huddinge, Sweden The project was multidisplinary allowing for a comprehensive approach to rheology and wheat chemistry. The lead author for publication was a graduate student, Stephen Chapman. Training will be provided for several more graduate students in the coming year. A worksop will be held this summer to introduce new rheological techniques to wheat quality personnel. TARGET AUDIENCES: Generally, the audience is wheat quality personnel. Wheat quality is very broad and involves wheat breeders, national wheat quality centers, industry, academics and wheat grading centers. The breakthrough in this project is development of a rapid rheological testing instrument that will allow rheology to be incorporated more easily into wheat quality programs. It provides a direct measure of gluten strength. The data generated here also points to a new idea of molecular structures responsible for elasticity in wheat gluten. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Gluten samples were obtained using the Glutomatic (Perten Instruments) followed by centrigugation to form cylindrical samples of around 3 g. The new instrument compresses the sample to a predetermined force and then measures the recovery of sample height. This is a free recovery allowing for the determination of pure elastic forces. The initial experiment was to determine the elastic properties of 15 samples representing major US wheat classes. Large deformation tensile test/stress relaxation tests were also done for these samples. Results showed that straining a gluten sample to 500% strain and holding resulted in stress relaxation giving way to an equilibrium value of the force. This is consistent with the idea of a crosslinked portion of gluten moving against a viscoelastic medium giving viscous dissipation. The better developed the network the higher would be the force. The compression-recovery (CORE) experiments revealed that wheat class is not a good indicator of gluten strength. In summary, the CORE instrument provides for a rapid and fundamental determination of gluten strength.
Publications
- Chapman, S.J., Mulvaney, S.J., Chinnaswamy, R., Rayas-Duarte, P. and Allvin, B. 2012. Large deformation stress relaxation and compression recovery of gluten representing different wheat classes. Journal of Cereal Science (accepted).
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Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: This work yielded two experimental methods that allow for unambiguous separation of delayed elastic effects and plastic flow in gluten. The first method is a "rapid" shear creep-recovery test, while the second method is a large deformation tensile test. Gluten in dough is subject to a wide range of shear and extensional stresses and strains in practical uses. For example, mixing, sheeting, oven rise, hand-pulled noodles, etc. These two tests are designed to provide objective measures of both the linear (small stress) and non-linear (large deformation) viscoelasticity of gluten. PARTICIPANTS: This is a joint project. Dr. Rayas-Duarte is a member of the Robert M. Kerr Food and AG Products Center and a profesor in Biochemistry. Her expertise is Cereal Chemistry. Dr. Chinnaswamy is with the government group GIPSA and FGIS. He has strong ties to the wheat industry. Mr. Bo Allvin is with Perten Instruments in Huddinge Sweden. We are all working together to understand dough and gluten and develop a commercial instrument for rapid determination of dough and gluten quality. TARGET AUDIENCES: Target audience is the wheat quality workers. These people are charged with evaluating and grading the quality of wheat and wheat products. The larger scientific community is also an intended audience. Information is disseminated at scientific meetings and wheat quality conferences and workshops. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
An important finding was that equilibrium or "near-equilibrium" values of the recoverable extensibility of gluten were obtained for creep times much shorter than those needed to achieve steady-state flow if the recovery time was substantially longer than the preceding creep time. All glutens showed substantial delayed elastic effects for the test conditions used here. Delayed elasticity is essentially a relaxation process, i.e. structural units "relax" into the equilibrium condition for the applied stress probably via a bond-breaking and re-forming process. The range of recoverable extensibility for the 5+10 cultivars was quite wide, varying by almost 400%, which suggests that Glu D1 subunits alone cannot explain differences in the viscoelastic properties of whole wet glutens. Further work is aimed at reconciling results of creep-recovery, dough and gluten extensibility, biochemical wheat quality and bread quality.
Publications
- Zhao, D. Mulvaney, S. Chinnaswamy, R. Rayas-Duarte, P. Allvin, B. and Wang, M. 2010. J. Cereal Science. 52:432-437.
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