Steady and Dynamic Shear Rheological Properties of Extrusion Modified Fenugreek Gum Solutions

• Published in: Food science and biotechnology Vol. 20; no. 6; pp. 1663 - 1668
• Main Authors: Chang, Yoon-Hyuk, Cui, Steve W
• Format: Journal Article
• Language: Korean
• Published: 2011
• Subjects: fenugreek gum; extrusion process; steady shear property; dynamic shear property
• ISSN: 1226-7708; 2092-6456

This study investigated the rheological properties of extrusion modified fenugreek gum solutions (0.5, 1.0, 1.5, and 2.0%, w/v) under steady and dynamic shear conditions. Fenugreek gum was extruded in a twin-screw extruder without an exit die to minimize a decrease in molecular weight of fenugreek gum during extrusion process. Both of the steady and dynamic shear rheological tests revealed that extrusion process did not substantially influence the steady and dynamic shear properties of the gum. The power law model was applied to describe the flow behavior of the extruded gum solutions. The extrusion modified fenugreek gum solutions exhibited a shear-thinning flow behavior at $25^{\circ}C$, and the values of consistency index (K) and apparent viscosity (${\eta}_{a,100}$) increased with an increase in the gum concentration. The magnitudes of storage modulus (G') and loss modulus (G") for the extrusion modified fenugreek gum solutions increased with increasing frequency (${\omega}$) and with increasing gum concentration.