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The Application of Numerical Methods and Complex Rheology in Understanding the Physical Properties of Frozen Bread Dough and Gluten-Free Dough

Shan, Shengyue
http://rave.ohiolink.edu/etdc/view?acc_num=osu1681908687668874

Abstract Details

2023, Doctor of Philosophy, Ohio State University, Food Science and Technology.
Foods are composite biomaterials that are heterogenous and complex in nature. Investigating food systems with the general principles of physics provides the possibility to understand the relationship between food structure and function on a fundamental level. The physical properties of food materials are intrinsically determined by the molecular assembly of components which determine the interaction between the material and processing procedures, and ultimately affect consumers’ acceptance. Measurement and quantification of the physical properties of food materials brings insights into the molecular interactions within the matrix. Bread dough, essentially a mixture of wheat flour and water, displays unique mechanical properties due to the viscoelasticity of the gluten proteins present in wheat flour. Rheology, the study of material deformation and flow, can be used to quantitatively demonstrate the interplay between water and other components present in dough. Frozen dough is widely used in the bakery industry for its economic benefits; however, freezing alters the state of water and adversely affects the dough quality. Examination of the frozen dough’s rheological properties can shed light on the mechanism of interactional changes induced by the phase change of water in the dough matrix. Freezing is a heat transfer process with a significant enthalpy change derived from phase change, and particularly due to the significant latent heat involved in freezing or thawing processes. Food freezing can be represented by a physical model that is governed by a partial differential equation (PDE) that must be solved numerically. However, the achievement of an accurate solution requires careful handling of the thermophysical properties of the food material. Besides water, gluten also plays a predominant role in determining dough rheology, which brings challenges to the development of gluten-free dough with desirable performance. Through fibrillization, the structure of globular proteins can be modified and form a fibrous structure, making it a potential gluten replacer. The overall objective of this dissertation study was to advance the understanding of protein-starch-water interactions within dough systems through the use of physical fundamental methods. In Study 1 (Chapter 3), specific heat smoothing methods were developed and compared in the numerical solution of the heat transfer PDE, which is often complicated by the significant discontinuity in the apparent specific heat derived from the latent heat release/absorption due to water phase changes. The optimal smoothing method showed comparatively less numerical oscillation, higher accuracy, faster computation speed, and simplicity in implementation. Recommendations were provided for the utilization of the smoothing methods under different circumstances. In Study 2 (Chapter 4), the effects of repeated freeze-thaw cycles on yeasted and non-yeasted frozen bread doughs were investigated by using a series of fundamental rheological tests. It was pointed out that the detrimental effects of freeze-thaw cycles were more pronounced in the extensional tests for both dough types. In Study 3 (Chapter 5), the deterioration mechanism of non-yeasted bread dough matrix under different freezing rates and frozen storage were investigated via fundamental rheological methods. Additionally, conformational and microstructural changes were evaluated by Fourier transformation infrared spectroscopy (FTIR) and environmental scanning electron microscopy (ESEM), respectively. The interaction between water and starch was altered by the freezing process and frozen storage, which impacted greatly the dough’s rheological properties. Fast freezing caused less damage to starch granules and preserved the extensional strength of the dough matrix relatively well; slow freezing damaged the starch granules, and led to an increased crystalline/amorphous ratio, which possibly initiated a water competition of starch with the gluten matrix. Rheological, conformation and microstructural changes were interrelated, and frozen-stored doughs displayed increased stiffness, reduced extensibility and resistance to extension, increased α-helix content as evaluated from amide III, and negatively affected the microstructure of gluten matrix in a similar manner. It was observed that gluten dehydration facilitated by ice recrystallization was the predominant mechanism causing dough deterioration during frozen storage. In Study 4 (Chapter 6), whey protein fibrils (WPF) were incorporated to mimic the fibrous network of gluten. The rheological properties and microstructure of the developed gluten-free doughs were evaluated and compared with gluten doughs. WPFs at pH 3.5 and 7 were characterized by Atomic Force Microscopy (AFM). Doughs with WPFs showed comparable linear viscoelasticity, tested by oscillatory amplitude sweep, oscillatory frequency sweep, and creep recovery in the linear viscoelastic region, to gluten dough. In the non-linear region, the rheological properties of WPF pH7 dough were similar to those of gluten dough. Although WPF pH3.5 dough showed higher strength than WPF pH7 dough and gluten dough in the creep recovery test under large deformation, it barely exhibited strain hardening properties, which are critical to assure bread baking performance. Overall, this research illustrated that the application of numerical methods and complex rheology can provide insights into the rheological changes and their relationships with the interactions among components in dough systems. Results from this research can be used to understand food matrices with similar composition and develop structure-function improvement strategies of food ingredients and processes aimed to preserve the rheological properties of frozen doughs.
Osvaldo Campanella (Advisor)
Sudhir Sastry (Committee Member)
Senay Simsek (Committee Member)
Dennis Heldman (Committee Member)
Macdonald Wick (Committee Member)
312 p.
Food Science
Physical properties; dough; rheology

Recommended Citations

Citations

  • Shan, S. (2023). The Application of Numerical Methods and Complex Rheology in Understanding the Physical Properties of Frozen Bread Dough and Gluten-Free Dough [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1681908687668874

    APA Style (7th edition)

  • Shan, Shengyue. The Application of Numerical Methods and Complex Rheology in Understanding the Physical Properties of Frozen Bread Dough and Gluten-Free Dough. 2023. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1681908687668874.

    MLA Style (8th edition)

  • Shan, Shengyue. "The Application of Numerical Methods and Complex Rheology in Understanding the Physical Properties of Frozen Bread Dough and Gluten-Free Dough." Doctoral dissertation, Ohio State University, 2023. http://rave.ohiolink.edu/etdc/view?acc_num=osu1681908687668874

    Chicago Manual of Style (17th edition)

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