Structural support of zein network to rice flour gluten-free dough: Rheological, textural and thermal properties

Abstract

Zein forms viscoelastic network with water to support the weak structure of gluten-free dough, but which requires temperature above 40 °C. A new method preparing zein network at room temperature using food-grade acetic acid was reported in our previous research. The current research explored the influence of zein network containing acetic acid on the rheology, texture, and tensile properties of rice gluten-free dough, as well as the interaction between zein network and rice flour. Results showed that zein network could act as a structural support material by binding rice flour particles to transmit its viscoelasticity and extensibility to rice dough, thus enhancing the ability of rice dough to resist external forces. The structural characteristics of zein-rice dough were both zein network-dependent and rice flour-dependent. α-Zein network could mix with rice flour particles more evenly than total-zein (T-zein, comprising α-, β- and γ-zein) network due to the thinner and denser fiber bundles, so the stretchability and thermal stability of α-zein-rice dough were greater than that of T-zein-rice dough, and the cooking loss of α-zein-rice noodle was less than that of T-zein-rice noodle. Compared with japonica rice dough and indica rice, waxy rice had less amylose, so the elasticity of zein-waxy dough was weaker than that of zein-japonica dough and zein-indica dough. And the gel network formed by amylose in rice during heating increased the elasticity of zein-rice dough. Additionally, the interaction between zein network and rice flour increased the ordered structure of starch in rice flour.