Strain-dependent assessment of dough’s polymer structure and functionality during the baking process

Abstract

During the baking process, the functionality of the heterogeneous dough matrix changes as the composing polymers experience conformational transition processes. The thermally induced structural changes affect the involvement and functionality of the polymers in the dough matrix. With the main hypothesis being that different types and magnitudes of strain exerted during the measurement would provide information on different structural levels and interactions, SAOS rheology in multiwave mode and large deformation extensional rheometry were applied to two microstructurally different systems. The functionality of the two systems, a highly connected standard wheat dough (φ ≈ 1.1) and an aerated, yeasted wheat dough (φ ≈ 2.3), depicting limited connectivity and strength of interactions, was accessed under different deformations and types of strains. Applying SAOS rheology, starch functionality prevailed on the behavior of the dough matrix. In contrast, gluten functionality prevailed the large deformation behavior. Using an inline fermentation and baking LSF technique, the heat-induced gluten polymerization was shown to increase strain hardening behavior above 70°C. In the aerated system, the strain hardening effect became already evident under small deformation testing, as the expansion of gas cells caused a pre-expansion of the gluten strands. The expanded dough matrix of yeasted dough was further shown to be substantially subjected to degradation once the network reached beyond its maximal gas holding capacity. Using this approach, the combined impact of yeast fermentation and thermal treatment on the strain hardening behavior of wheat dough was revealed for the first time by LSF. Furthermore, the rheological properties were successfully linked to oven rise behavior: a decreasing connectivity combined with the initiation of strain hardening by fast extension processes occurring in the yeasted dough matrix during the final baking phase was linked to limited oven rise functionality prematurely around 60°C.

Wheat Flour Quality Assessment by Fundamental Non-Linear Rheological Methods: A Critical Review

“…The difference in viscosity at different strains was much larger in the temperature range of 25–45 °C than in the range of 60–95 °C ( Figure 11 b), suggesting a higher degree of strain stiffening behavior for wheat flour dough below 60 °C than above [ 7 ]. This finding concurred with the findings of others [ 30 , 107 , 108 ] and supported the possibility of better predicting the baking quality of wheat flours when extensional tests were conducted below 60 °C.…”

“…For this purpose, the stress ( σ ) values obtained from extensional tests at a given extensional strain rate are ( ) plotted versus deformation ( ε ) on a logarithmic scale. Furthermore, the slope of this curve is defined as the strain hardening index [ 24 , 29 , 30 ]. SHI determined by the lubricated squeezing flow tests was found to play a crucial role in determining crumb fineness, as evidenced by the correlation (r 2 = 0.83) between these parameters.…”

“…Thus, reaching the extensibility limit might explain the triggering of strain stiffening at the early stages of baking. On the other hand, a decrease was reported in the strain stiffening index of wheat flour dough between the temperatures of 50 °C and 70 °C [ 30 ], which indicated that the temperature of 50 °C was a critical temperature in terms of strain stiffening behavior. However, as discussed above, most of the studies evaluating the extensional properties of wheat flour doughs to predict baking quality have been conducted at around 30 °C, except for the study conducted by Dobraszczyk and Salmanowicz [ 107 ].…”

“…Studies have shown that fundamental large strain rheology could be used to differentiate different types of wheat flours, while small strain rheology was unable to differentiate between functionally very different flours [ 8 ]. Fundamental methods employed for exploring the mechanical properties of wheat flour dough under large deformations include capillary flow [ 28 ], lubricated squeezing flow [ 7 , 24 , 29 , 30 ], stress relaxation [ 7 , 31 , 32 ], stress growth [ 19 ], creep and creep recovery [ 24 , 33 , 34 ], and large amplitude oscillatory shear tests [ 6 , 21 , 26 ].…”

The Effect of Carboxymethyl Cellulose Sodium on the Proofing Tolerance and Quality of Frozen Dough Steamed Bread

“…From Figure 9 A,D, it is evident that the FDSB with 0.0% CMC-Na had the least dense gluten network wrapped around the starch granules. Figure 9 G shows that 1.0% CMC-Na caused the greatest cross-linking of the gluten network, proving that CMC-Na improved the connections and flexibility of the dough structure, which might have been due to the enhancement of the intermolecular forces and disulfide bond [ 17 , 65 ] and the improvement of the viscoelasticity of the dough by the interaction of CMC-Na with water. However, a content of 1.6% ( Figure 9 H) instead resulted in a network breakdown similar to that of the control sample ( Figure 9 A), which was caused by the physical barrier of starch clusters, as shown by the arrow in Figure 9 L. Therefore, the morphology of starch granules was obviously affected.…”