Structural Variations of Wheat Proteins under ultrasound treatment

The present work investigated the effects of ultrasound on the hydrogen-bond strength, the secondary and network structures, granule size and microstructures of gluten, glutenin and gliadin, in order to explicate the possible mechanisms of ultrasound-assisted dough processing. The results showed that ultrasound weakened the intermolecular hydrogen-bond strength of protein. After sonication, the contents of β-turns and β-sheets decreased and increased, respectively, which was especially evident under medium-intensity sonication (23.08 W/L; 30 min) among low-, medium- and high-intensity. This implied that ultrasonic treatment facilitated the conversion of β-turns into β-sheets. Sonicated gluten proteins have uniform sizes and exhibit a flocculent, rough, fluffy and relatively dispersed structure with loosely distributed particles. Sonicated glutenin has a complete network structure with more ordered crosslinks between molecules. For sonicated gliadin, small pores can be observed on the surface and its overall structure appears fluffy and enlarged. Generally, ultrasound could affect the protein structure by hydrogen-bonding interactions, as well as the molecular crosslink, granule size and distribution, mechanical properties and air chamber structure.