Amyloid fibrils-regulated high-moisture extruded soy proteins: Texture, structure, and taste

Abstract

The textured vegetable proteins (TVP) prepared by high-moisture extrusion (HME) are becoming ideal substitutes for animal proteins due to their similar texture and taste of muscle fibers. However, the fibrous structure and texture characteristics of HME-TVP cannot be effectively regulated. In the current work, the effects of soy protein fibrils (SPF) on the texture, structure, and tastes of high-moisture extruded soy protein isolates (SPI) were investigated to improve the quality of extruded SPI products. Besides, the fluorescence polarization spectroscopy method was established to scientifically evaluate the degree of anisotropy of extrudates at the molecular level based on the intrinsic fluorescence properties of proteins. The results showed that the presence of 10 wt% SPF decreased the hardness of SPI extrudate by 35% while increasing its anisotropic index by 32%, indicating that the self-assembled protein fibrils modulated the texture and promoted the formation of fiber-rich structures of the extrudates with a defined fiber orientation. The involvement of SPF also enhanced the water holding capacity of extrudates with improved cooking stability. Furthermore, the bitterness and astringency values of the SPI extrudates were reduced by 46% and 33%, respectively, in the presence of an SPF level of 20 wt%. These findings would provide technical support for the development of theories and methods for the quality-directed regulation of HME-TVP.