Morphological Distribution and Structure Transition of Gluten Induced by Various Drying Technologies and Its Effects on Chinese Dried Noodle Quality Characteristics

The effects of three drying methods, hot air (HA), microwave (MW), and radio frequency (RF), on the protein structure and texture properties of Chinese dried noodles were investigated. The results of the Raman spectra showed that the main change in the secondary structure is an increase in the number of β-sheets, and the main change in the tertiary structure was an increase in the gauche-gauche-gauche content. Microstructure analysis showed that dielectric drying (MW and RF) enables the dough to form a more ordered network structure. In addition, dielectric drying reduced the content of free sulfhydryl groups, increased the content of glutenin macropolymer, and enhances the degree of protein aggregation, as evidenced by size-exclusion high-performance liquid chromatography and fluorescence spectroscopy. The results of the thermogravimetric analysis also demonstrated that dielectric drying enhances the stability of the protein network by enhancing the cross-linking of gluten proteins. The results of the quality characteristics analysis showed a significant increase in textural and cooking properties of the dielectric dried noodles. This study showed that dielectric drying affects the functional properties and quality of the final product by changing the conformation of the protein; this change is most evident in MW drying.