Molecular conformation and dilute solution properties of barley β-glucan: unveiling β-glucan as a highly flexible biopolymer under different processing conditions

Background

The functional properties of food fluids containing hydrocolloids are influenced by temperature, soluble salts, pH and the presence of sugars. In this research, the properties of a dilute barley β-glucan (BBG) solution were evaluated in the presence of various factors. Different models were explored to determine the intrinsic viscosity of BBG.

Results

The results indicated that the models of Higiro and Tanglertpaibul–Rao were more efficient in determining the intrinsic viscosity of BBG at different temperatures, different pH, the presence of sodium chloride, calcium chloride, and sucrose. Every 10 °C increase in temperature from 25 to 65 °C caused a decrease in intrinsic viscosity by 7.8, 10, 5.7 and 7.2%, respectively. In relation to the non-ionic structure of BBG, the presence of monovalent and bivalent salts had a negligible effect on reducing the intrinsic viscosity. The increase in pH from 3 to 7 caused a rise in intrinsic viscosity. But a further increase in pH, up to 9, caused a decrease in intrinsic viscosity. However, these changes were not significant and indicated that the non-ionic structure of BBG was independent of the pH. Since the constant b values of BBG were close to 1 at all temperatures, salt concentrations, different pH values and different sucrose concentrations, it can be assumed that the structure of BBG in the dilute range was close to the random coil conformation.

Conclusions

The values of flexibility index and activation energy for BBG were calculated as 789.52 and \({0.65\times 10}^{7}\) J/kmole, respectively, which indicated that this hydrocolloid was highly flexible in different environmental conditions and it was independent of the processing temperature. Therefore, BBG can be recommended as a natural thickener in food-related fluids.

Graphical Abstract