The behavior of amaranth, chickpea, millet, corn, quinoa, buckwheat and rice doughs under shear oscillatory and uniaxial elongational tests simulating proving and baking

Abstract

Shear oscillatory and uniaxial elongational tests performed at 30C were used to simulate gluten-free dough proving; shear oscillatory temperature ramp (30–90C) was used to simulate baking. In test simulating initial stages of proving the differences in wheat and gluten-free dough (amaranth, buckwheat, chickpea, corn, quinoa, millet and rice) behavior were most evident from the higher values of elastic (105 Pa) and viscous moduli (104 Pa) of gluten-free doughs compared with the values of elastic (104 Pa) and viscous moduli (103 Pa) of wheat dough. During later stages of proving, the region of elastic, time-dependent viscoelastic and viscous deformations of gluten-free doughs were very narrow, and moreover varied among the investigated gluten-free doughs. The stress required for dough rupture also differed among the tested gluten-free doughs. While rice, quinoa and millet dough ruptured under the stress of 10.6 kPa, 9.5 kPa and 9.2 kPa, respectively, significantly the lower stresses were required to rupture chickpea (4.9 kPa), amaranth (4.7 kPa), buckwheat (4.0 kPa) and corn (3.2 kPa) dough. Hencky strains at the moment of gluten-free doughs rupture were, however, quite similar (0.6–0.7). During oscillatory test simulating baking, complex viscosity of gluten-free doughs was up to 2–3 log cycles higher than the viscosity of wheat dough. Practical Applications: The results confirmed known significant differences between the behavior of gluten-free and wheat doughs, which occurred during proving as well as baking. Compared with wheat gluten proteins, network in gluten-free doughs exhibited high values of elastic and viscous moduli, narrow region of elastic, time-dependent viscoelastic and viscous deformations, as well as high peak complex viscosity during heating. This behavior indicated lower gluten-free dough ability to increase the gas-dough interface area and to accumulate leavening gas in pores, which may decrease the bread-making quality of gluten-free doughs. Moreover, the differences in the behavior among gluten-free doughs were described. It can be assumed the differences are in close relationship with the characteristics of arabinoxylan networks. The results are practically applicable in gluten-free dough quality testing as well as in the development of new formulas aimed at the improvement of the quality of yeast-leavened gluten-free bread. © 2016 Wiley Periodicals, Inc.