Effect Of Waxy Wheat Flour On Rheofermentometer Rheological And Baking Properties Of Frozen Dough And Bread

In this paper, frozen dough properties and bread baking properties with various levels of waxy wheat flour (WWF) were investigated.Compared to commercial bread flour (CBF), WWF had a higher water retention capacity at different temperatures and frozen storage. Compared with nonwaxy wheat starches, the waxy wheat starch exhibited a higher water retention capacity, swelling power, solubility, freeze-thaw stability and a lower hardness of starch gel.Rapid viscosity analyzer (RVA), Differential Scanning Calorimetry (DSC) and Mixolab were used to study the effects of WWF on rheological properties of flours and doughs. Addition of WWF decreased the peak time and setback, increased the gelatinization enthalpy, however, it did not affect the pasting temperature significantly. Substitution with WWF could significantly increase water absorption (from 63.0% to 73.6%) and did not significantly affect the dough stability time (except for the 100% WWF) but did increase the degree of protein softening (from 0.58 to 0.66 Nm) and decrease theαvalue, while C5-C4 significantly declined ( from 0.4 to 0.25 Nm). Moreover, addition of WWF significantly decreased theβvalue (srarch gelatinization rate). Dynamic rheometer was used to analyze the effects of WWF on the dynamic rheological properties of frozen dough. During frozen storage, the storage modulus (G') and loss modulus (G") of dough gradually decreased. However, addition of WWF decreased slowly during frozen storage for G' and G". This indicated that addition of WWF could enhance the frost resistance of dough.F3 Rheofermentometer results showed that compared with the control dough, WWF decreased Hm and R as well as increased total gas production and H′m to some extent. During frozen storage, various parameters (e.g., Hm, H′m, R) of dough gradually decreased, but dough with greater WWF had less change in these parameters. For example, compared to 7 d frozen storage, the changes in Hm during 90 d frozen storage were 17.5%, 14.9%, 12.3% and 15.5% for 0%, 10%, 20% and 30% waxy wheat dough, while in R were 3.1%, 2.8%, 2.3% and 2.2%, respectively. Regardless of whether or not the dough had been frozen, addition of WWF increased yeast colony count, and during frozen storage, yeast colony count of dough with WWF decreased slowly.We studied the effect of WWF on ice crystal and microstructure of frozen dough by DSC and Scanning Electron Microscopy (SEM). DSC studies showed that frozen dough with WWF had lower freezable water (FW) content and during frozen storage, dough with higher WWF had less increase in FW, for example, FW of 0% WWF dough increased by 26.39% during the 90 d storage period whereas samples with 10%, 20% and 30% WWF increased by 22.01%, 21.88% and 21.51%, respectively. The results of SEM of frozen dough showed that: compared with respectively fresh dough, the gluten network of frozen dough with WWF suffered less damage, indicating that addition of WWF could reduce the damage of gluten network and improve the structure of the dough during frozen storage.Effects of WWF on baking characteristics were analyzed through the determination of specific volume, color, texture, and sensory evaluation of corresponding breads. Substitution with WWF resulted in lower specific volume, darker color and lower hardness. The quality of all frozen dough breads decreased to some extent; however, waxy wheat bread showed better anti-aging performance and a slower decline in quality. During frozen storage, sensory evaluation revealed bread made with 10% WWF was most favored.