Rheological and micro-rheological properties of chicory inulin gels

Authors: Xu, Jingyuan - James; Kenar, James - Jim

Submitted to: Gels
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2024
Publication Date: 2/28/2024
Citation: Xu, J., Kenar, J.A. 2024. Rheological and micro-rheological properties of chicory inulin gels. Gels. 10(3). Article 171. https://doi.org/10.3390/gels10030171.
DOI: https://doi.org/10.3390/gels10030171

Interpretive Summary: Inulin is a biodegradable soluble fiber existing in many plants and has many potential applications in food and non-food products such as cosmetic gels and wound-healing materials. In order to identify potential novel applications of inulin, ARS researchers in Peoria, Illinois investigated the flow behavior of inulin in water. We explored the effects of concentration on the properties of the inulin gels. We found that the flow behavior of inulin gels can be manipulated through different concentrations. Therefore, we can prepare various inexpensive biodegradable inulin gels and tailor them toward their different uses, for example as hair gels or wound-healing materials.

Technical Abstract: As a soluble fiber, inulin is in many plants and has many applications in food and non-food products. In this work, we investigated the rheological properties of inulin dispersions at seven concentrations. The linear viscoelastic properties of inulin were determined using a conventional mechanical rheometer. At 25wt%, inulin exhibited fluid-like viscoelastic liquid behavior. However, when concentrations were =27.5wt%, inulin exhibited gel-like viscoelastic properties. The viscoelastic properties (moduli and viscosities) increased with increasing inulin concentration. The high-frequency linear rheological properties of inulin also were investigated using diffusion wave spectroscopy (DWS). DWS measurements showed the amplitude of complex moduli (|G*(')|) of inulin gels (=27.5wt%) to be proportional to ½ power law of the frequency and suggests inulin gels behave similar to flexible polymers. The non-linear steady shear experiments demonstrated that inulin exhibited shear-thinning behavior that was well-fitted by a power law constitutive model. The trend of the power law exponent from the experiments indicated that the shear-thinning extent for inulin was greater as the inulin concentration increased. These results can be used to direct further food and non-food applications for inulin gels.