Micro-heterogeneity and micro-rheological properties of high-viscosity barley beta-glucan solutions studied by diffusion wave spectroscopy (DWS)

Authors: Xu, Jingyuan - James; Inglett, George; Liu, Sean; Boddu, Veera

Submitted to: Food Biophysics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/14/2016
Publication Date: 12/1/2016
Citation: Xu, J., Inglett, G.E., Liu, S.X., Boddu, V.M. 2016. Micro-heterogeneity and micro-rheological properties of high-viscosity barley beta-glucan solutions studied by diffusion wave spectroscopy (DWS). Food Biophysics. 11(4):339-344.

Interpretive Summary: The heart disease is the leading cause of death in the United States. Many scientific research reports suggest that reducing total and LDL cholesterol concentrations can decrease the risk of heart attack. Soluble fiber ß-glucan is one of the key dietary materials in the healthy food products known for reducing serum cholesterol levels. Several new food products containing high amount of ß-glucan have been invented and many research have been done for ß-glucan. However, the properties and the structure-function relationship of ß-glucan are still not clearly understood. This paper examines some of the physical properties of the high-viscosity barley ß-glucan. Using a technology named Diffusion Wave Spectroscopy (DWS), we studied the flow behavior and micro-rheology of ß-glucan. The results of this research give us much more insight of physical properties for ß-glucan. It is also shown that the technique of DWS is powerful for studying the properties of food systems.

Technical Abstract: Soluble fiber ß-glucan is one of the key dietary materials in healthy food products known for reducing serum cholesterol levels. The micro-structural heterogeneity and micro-rheology of high-viscosity barley ß-glucan solutions were investigated by the diffusing wave spectroscopy (DWS) technology. By comparing the mean-square displacement (MSD) of the microspheres imbedded in eight concentrations of ß-glucan solutions, we found that the solutions exhibited nearly homogeneous behavior at =0.1 %, but the material showed a clear degree of heterogeneity at =0.25 %. Micro-rheology investigation revealed that ß-glucan solutions displayed nearly perfect viscous behavior at =0.1 %, but the property changed into viscoelastic one at =0.25 %. The magnitude of high-frequency viscoelastic moduli for the 0.25 % - 0.75 % ß-glucan solutions can be characterized by 'G*' ' '3/4, which is the semi-flexible polymer behavior. However, the magnitude of high-frequency viscoelastic moduli ('G*') for the 1.0 % - 1.25 % ß-glucan solutions is proportional to '1/2, which is the flexible polymer behavior. All micro-structural heterogeneity and micro-rheological property shifts occurred in relatively small concentration ranges.