The influence of native wheat lipids on the rheological properties and microstructure of dough and bread

dc.contributor.authorCropper, Sherrill Lyne
dc.date.accessioned2015-04-13T20:13:50Z
dc.date.available2015-04-13T20:13:50Z
dc.date.graduationmonthMay
dc.date.issued2015-04-13
dc.description.abstractBread quality and final crumb grain are reflective of the ability for wheat flour dough to retain and stabilize gas cells during the baking process. The visco-elastic properties of dough allow for the incorporation of air cells and expansion during fermentation and baking. The gluten-starch matrix provides the backbone support. However, following the end of proofing and during the beginning of baking, the structure weakens due to over-extension and expansion and the matrix begins to separate and eventually break down. Native wheat lipids, which are found in small quantities in wheat flour, provide a secondary support for gas cell stabilization because of their amphiphilic characteristics and ability to move to the interface and form condensed monolayers. The objectives of this research were to evaluate the influence of native wheat lipids on the rheological properties of dough and the microstructure of bread. Native wheat lipids were extracted from straight-grade flour and separated into total, free, bound, nonpolar, glycolipids, and phospholipids using solid-phase extraction (SPE) with polar and nonpolar solvents. Defatted flour was reconstituted using each lipid fraction at a range of levels between 0.2% and 2.8%. Dough and bread were made following AACC Method 10-10.03. Rheological testing of the dough and evaluation of the microstructure of the bread was conducted using small and large deformation testing, C-Cell imaging, and x-ray microtomography analysis to determine changes in visco-elastic properties and gas cell structure and distribution. Rheological assessment through small amplitude oscillatory measurements demonstrated that nonpolar, phospholipids, and glycolipid fractions had a greater interaction with both proteins and starch in the matrix, creating weaker dough. Nonpolar, phospholipids, and glycolipids, varied in their ability to stabilize gas cells as determined by strain hardening index. C-Cell imaging and x-ray microtomograpy testing found that treatments containing higher concentrations of polar lipids (glycolipids and phospholipids) had a greater effect on overall loaf volume, cell size, and distribution. This illustrates that level and type of native wheat lipids influence the visco-elastic properties of dough and gas cell size, distribution, cell wall thickness, and cell stability in bread.
dc.description.advisorHulya Dogan
dc.description.advisorJon M. Faubion
dc.description.degreeDoctor of Philosophy
dc.description.departmentDepartment of Grain Science and Industry
dc.description.levelDoctoral
dc.identifier.urihttp://hdl.handle.net/2097/18924
dc.language.isoen_US
dc.publisherKansas State University
dc.rights© the author. This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/
dc.subjectNative wheat lipids
dc.subjectRheology
dc.subjectX-ray Microtomography
dc.subjectMicrostructure
dc.subjectC-Cell Imaging
dc.subject.umiFood Science (0359)
dc.titleThe influence of native wheat lipids on the rheological properties and microstructure of dough and bread
dc.typeDissertation

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