Browsing by Person "Becker, Thomas"

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Micro-scale shear kneading: Gluten network development under multiple stress-relaxation steps and evaluation via multiwave rheology
(2022) Vidal, Leonhard Maria; Braun, Andre; Jekle, Mario; Becker, Thomas
To evaluate the kneading process of wheat flour dough, the state of the art is a subsequent and static measuring step on kneaded dough samples. In this study, an in-line measurement setup was set up in a rheometer based on previously validated shear kneading processes. With this approach, the challenge of sample transfer between the kneader and a measurement device was overcome. With the developed approach, an analysis of the dynamic development of the dough is possible. Through consecutive stress–relaxation steps with increasing deformation, a kneading setup in a conventional rheometer is implemented. Fitting of the shear stress curve with a linearization approach, as well as fitting of the relaxation modulus after each kneading step, is a new way to evaluate the matrix development. Subsequently, multiwave rheology is used to validate the kneading process in-line. The shear kneading setup was capable of producing an optimally developed dough matrix close to the reference kneading time of 150 ± 7.9 s (n = 3). The linearization approach as well as the power-law fit of the relaxation modulus revealed gluten network development comparable to the reference dough. With this approach, a deeper insight into gluten network development and crosslinking processes during wheat flour dough kneading is given.
Microscopic analysis of gluten network development under shear load—combining confocal laser scanning microscopy with rheometry
(2023) Vidal, Leonhard Maria; Ewigmann, Hans; Schuster, Clemens; Alpers, Thekla; Scherf, Katharina Anne; Jekle, Mario; Becker, Thomas
A comprehensive in‐situ analysis of the developing gluten network during kneading is still a gap in cereal science. With an in‐line microscale shear kneading and measuring setup in a conventional rheometer, a first step was taken in previous works toward fully comprehensible gluten network development evaluation. In this work, this setup was extended by an in‐situ optical analysis of the evolving gluten network. By connecting a laser scanning microscope with a conventional rheometer, the evaluation of the rheological and optical protein network evolution was possible. An image processing tool for analyzing the protein network was applied for evaluating the gluten network development in a wheat dough during the shear kneading process. This network evaluation was possible without interruption or invasive sample transfer comparing it to former approaches. The shear kneading system was able to produce a fully developed dough matrix within 125% of the reference dough development time in a classical kneader. The calculated network connectivity values from frequency testing ranged over all samples was in good agreement with traditional kneaded wheat dough just over peak consistency.
Multi‐scale dough adhesion analysis: Relation between laboratory scale, pilot scale and human sensory
(2023) Vogt, Ulrike Therese; Kwak, Ju Eun; Fahmy, Ahmed Raouf; Laukemper, Rita; Henrich, Alexander; Becker, Thomas; Jekle, Mario
Undesired dough adhesion is still a challenge during the production of baked goods. There are various methods for determining the adhesive texture properties of dough. In the majority of scientific papers, dough stickiness is measured analytically by the force‐distance recording of dough detachment. In this study, we describe a new multi‐scale approach to compare dough adhesion phenomena in a laboratory, pilot sale and human sensory assessment. In it, the adhesive material properties of dough were investigated using a pilot scale toppling device representing dough adhesion behavior in the production process, in the laboratory by texture analysis with the Chen–Hoseney method and furthermore with a new, implemented non‐oral human sensory analysis. To simulate different dough adhesion behavior, the dough mechanical and adhesion properties were varied by applying dough‐modifying enzymes and different dough storage times. The structural changes in the different wheat dough system were compared by rheological characterization. By characterizing the different adhesion phenomena of the doughs, the sample with bacterial xylanase showed the highest values after 80 min of storage time in all three methods. Correlation analysis revealed a strong relationship between the detachment time (pilot scale) and human sensory assessment attributes (Force R = 0.81, Time R = 0.87, Distance R = 0.92, Stickiness R = 0.80) after 80 min of storage time. Even though human sensory assessment showed limits in the detectability of differences in dough adhesion behavior compared to the Chen–Hoseney method, it was better suited to predict machinability.
Texture modulation of starch‐based closed‐cell foams using 3D printing: Deformation behavior beyond the elastic regime
(2022) Fahmy, Ahmed Raouf; Jekle, Mario; Becker, Thomas
3‐dimensional printing is a novel processing method used for the design and manipulation of food textures. The systematic characterization and modulation of 3D printed food textures is imperative for the future design of sensory profiles using additive manufacturing. For 3D printed closed‐cell food foams, the clarification of the deformation behavior in relation to design parameters is of interest for the processing of customized food textures. For this reason, we studied the deformation behavior of 3D printed and thermally stabilized closed‐cell starch‐based foams beyond the elastic regime. Periodic spherical bubble configurations at different porosity levels were used to modulate the deformation behavior of the printed foams. From a processing perspective, the integration of in‐line thermal stabilization was used to eliminate post‐processing and to control the moisture content of the starch‐based system. Compression analysis combined with FEM simulations were performed to characterize the strain rate dependency of textural properties, the stress relaxation, and the foam's stress–strain behavior with respect to the design porosity and bubble distribution. Results showed that the stress relaxation is solely dependent on cell wall properties while different stress–strain regimes showed distinct dependencies on design parameters such as bubble size and distribution. Consequently, the precise control of the large deformation behavior of foods using 3D printing is challenging due to the superposition of structural and geometrical dependencies. Finally, through the presented approach, the structure‐deformation relations of 3D printed closed‐cell food structures are adequately described.