Effect of Extrusion Treatment on the Structural and Functional Properties of Enzymatic Hydrolysis of Foxtai Millet Flour Protein

In this study, foxtail millet was used as raw material. The purpose of research was to investigate the changes of the properties and structures of four foxtail millet proteins, including albumin, glutelin, gliadin and globulin, after treatment by extrudating with α-amylase. The results demonstrated the increased water holding capacities, decreased foaming abilities, as well as the loss of the contents of several amino acids of these foxtail millet proteins under all extrusion conditions. Additionally, after extruding with enzyme, the contents of these proteins decreased, whereas the emulsification abilities increased. Among these proteins, the emulsification ability of gliadin was increased, while the foam stabilities of gliadin and glutelin were enhanced. Additionally, extruding with amylase resulted in less protein bands of albumin and globulin on gel. Furthermore, the secondary and tertiary structures of these foxtail millet proteins were comparable along extruding with enzyme, with minor blue shift. In conclusion, extruding with enzyme could improve the properties of foxtail millet proteins, with little influence on the secondary and tertiary structures. These findings indicate that the pregelatinization foxtail millet flour obtained with enzymatic extrusion processing technology could be used for an ideal functional food resource.