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Abstract Spinnability and rheological properties of soy protein are studied for potential application in food products. It has been considered impossible to spin globular proteins due to the difficulty in extending the molecules to achieve high degree of intermolecular entanglement. In order to improve the spinnability of globular proteins, other polymers were incorporated. This paper shows a good spinnability of 100% globular soy protein. In this work, aqueous urea/reductant system is selected for efficient stretch and entanglement globular soy proteins for fiber spinning. In this system, hydrogen bonds, hydrophobic and electrostatic interaction were disrupted by urea, while disulfide bonds were cleaved by reductants. Moreover, the backbones of globular soy proteins were not severely destroyed, rendering the stretched globular protein spinnable and the spun fibers mechanically robust. Relationship between rheological properties and spinnability of globular soy protein solutions is quantified. In order to be spinnable, globular soy proteins should be highly stretched, and thus entangled with preserved backbones. Graphical abstract Image 1 Highlights • Globular soy protein could be spun to fibers after proper dissolution. • A solvent system selected for efficient intermolecular entanglement of soy protein. • Relationship quantified between rheological property and spinnability of soy protein. • Soy protein fibers are potential candidates for various food applications. [ABSTRACT FROM AUTHOR]

For the first time, rheological behavior of soy protein isolate (SPI) solution with high concentration for fibers and films was studied. The results showed that SPI could be readily dissolved in urea/sodium sulfite aqueous system, and the SPI solution is suitable for wet spinning and film casting. The effects of concentration, temperature, and shear rates on the rheological properties of SPI solution were studied. Viscosity of SPI solution decreases with increasing temperature, which is good for the preparation of solution with high concentration and regenerated SPI fibers/films with good properties. All solution samples exhibited thixotropic behavior, which were different from traditional polymer solution for wet spinning and film casting process. Both in forward and backward measurements were carried out by the Power Law model. Under constant shear rates (80-160 s −1 ), 18 wt% SPI solution was chosen to study the dependence of viscosity on time. Second order structural kinetic model, Weltman model, first-order stress decay models with zero and none-zero equilibrium stress values were used to fit the rheological data. Among the four models, Weltman model is more appropriate to fit the thixotropic data. [ABSTRACT FROM AUTHOR]