Elucidation of steady shear flow properties of β‐glucan solutions under different thermal and environmental conditions by different rheological models

Abstract

AbstractThe present study was carried out to investigate flow behavior of β‐glucan of hull‐less barley cultivar Lut, as influences of concentrations (0.25, 0.5, 0.75, and 1%); temperatures (5, 25, 45, and 60°C); NaCl and CaCl2 salts; pHs; and sugar. Shear stress data were fitted versus shear rates using the models with yield stress such as Casson, Heinz–Casson, Mizrahi–Berk, Generalized Herschel–Bulkley, Vocaldo, and Schulmann–Haroske–Reher together with general model of power law. Power law model provided the most appropriate fit for flow behavior properties of β‐glucan at various concentrations and temperatures with high R2 and low root mean square error. By increase in temperature, consistency coefficient was decreased and flow behavior index was enhanced. Results showed that consistency coefficient increased nonlinearly along with increase in concentration. The highest dependency of consistency coefficient on temperature was observed at 1% concentration (Ea = 31.4 kJ/mol). Apparent viscosity was decreased at 1% concentration of salts. The reduction of apparent viscosity was sharper for NaCl than CaCl2. The highest value of consistency coefficients and the lowest flow behavior indices were found in pH range of 5–7. Increase in sucrose concentration up to 30% elevated consistency coefficient but had no significant effect on flow behavior index. In general, the results showed that the flow behavior of β‐glucan in different conditions can be well interpreted by most rheological models. β‐glucan can also be introduced to the food industry as a suitable thickener in the variety of food solutions with different physicochemical properties (temperature, pH, and the presence of salts and sugar).Practical ApplicationsResearch in the field of rheological behaviors of food fluids plays critical role in designing the processes, transportation systems (pumps and pipes), heat transfer equipment (heat exchangers and evaporators), and determination of the correlation between sensory and textural properties of foods. Temperature, concentration, and environmental conditions (pH, salt, and sugar) are predicted to have a significant effect on the flow behavior of β‐glucan solution. Evaluation of flow behavior of β‐glucan solutions using rheological models provides a reliable prediction about flow behavior of them under various conditions of processing, production, and storage. Food liquids experience different concentrations, temperatures and pH during production, storage, transportation, distribution, marketing, and so forth. Therefore, modeling and simulating the flow behavior of β‐glucan solutions helps foods containing this dietary fiber (as a hydrocolloid) to easily withstand various environmental and thermal conditions in industrial processes without any problems.