Effect of Zein on Buckwheat Dough Properties

To investigate the effect of zein addition on rheological properties of buckwheat-based gluten-free dough, atmosphere puffed tartary buckwheat flour was mixed with common buckwheat flour at a ratio of 1:1 to make a mxied base flour (MBF). Zein was plasticized with 90% ethanol solution, and then 0%, 5%, 10%, 15%, and 20% (MBF based) of the plasticized zein was mixed with MBF and water, respectively, to make a buckwheat-based gluten-free dough (BBGD) with gradient content of zein. The static rheological properties of dough (texture properties, tensile properties and stress relaxation properties), dynamic rheological properties, optical properties (chromaticity and reflectivity) and microstructure were measured. Results showed that, with the increasing of zein content from 0% to 20%, the hardness of BBGD decreased from 482.38 g to 346.60 g, while elasticity, tensile distance, and tensile strength increased from 0.21 to 0.29, 15.44 to 38.16 mm, and 13.10 to 72.04 g, respectively. The residual stress, viscoelastic coefficient and relaxation time increased significantly compared with the control (P<0.05), but decreased gradually with the increasing of zein addition. The G' and tanδ values, surface brightness, and reflectance rate of the dough were significantly improved, and the protein fiber was obviously observed in the microstructure compared with the control. The above results showed that zein could effectively improve the defects of poor adhesion and extensibility of buckwheat gluten-free dough. This study would provide a new way for improving the structure and processing properties of gluten-free foods.