Frozen dough made using flour of higher protein content (9.5-11 %) had better resistance to freezing damage than those made using flour of lower protein content and resulted in steamed bread whose specific volume, form ratio and texture were closer to those of bread made from fresh dough. The effects of flour protein content and freezing conditions (freezing air temperature and air speed) on dough and steamed bread quality were investigated in this study. Compared to nonfrozen control, the freezing process caused a deterioration to gluten network as well as a decrease in yeast activity, which resulted in lower maximum dough height and less total gas production, leading to steamed bread of lower specific volume and form ratios, and increased hardness. Faster freezing rates resulted in dough with higher extensibility and a less damaged dough microstructure but led to a decrease in total gas production as yeast activity was compromised. The extreme freezing conditions of −20°C and air speed of 0 m/s and −40°C and air speed of 6 m/s had the poorest dough and steamed bread quality. Samples frozen at −30°C had better form ratio of steamed bread than those frozen at −20°C and −40°C, while those frozen at −40°C had the lowest specific volume. A moderate air speed of 3 m/s resulted in higher volume of total gas production and dough height, as well as better steamed bread texture.

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Cereal Chem. 92(3):236-245The impact of freezing on dough rheology, fermentation performance, and final steamed bread quality was investigated in this study. Also, the incorporation of sodium alginate and xanthan gum into the frozen dough formulation, in comparison with 0.1% salt, was studied to test their suitability as frozen dough improvers. Incorporating these hydrocolloids into steamed bread revealed their totally different characteristics from those in baked bread. Freezing of dough led to diminished specific volumes of proofed dough and steamed bread, and it also caused higher crumb firmness for steamed bread. The incorporation of sodium alginate and xanthan gum did not improve the quality of the steamed bread but led to further reduction in specific volume and increase in crumb firmness at the higher levels of 0.3, 0.5, and 1.0% and 0.07 and 0.1%, respectively. Xanthan gum and sodium alginate showed dough strengthening effects by increasing resistance to uniaxial deformation, bubble burst stress, and declining dough weakening coefficients at these levels, but decreased dough extensibility and bubble burst strain were revealed at these concentrations tested. † Corresponding