Rheological properties and stabilizing effects of high-temperature extracted flaxseed gum on oil/water emulsion systems

Flaxseed gums (FG) previously reported were mostly isolated from hulls and seeds under a relatively low temperature, which led to an incomplete structural and functional understanding of the entire gum. In addition, the influences of processing conditions on the functional properties of FG have rarely been studied. In this study, FG was extracted by water at high temperature (90 °C) followed by ethanol precipitation. The physicochemical characteristics of the high temperature extracted FG were investigated, including its rheological and emulsion stabilizing properties in aqueous solution. The influences of homogenization and heating-cooling treatments on the functional properties of FG were also examined. Results indicated that FG could form a gel in aqueous solution (>0.5 wt%) at room temperature (25 °C). Mechanical shearing forces derived from homogenization (50 MPa) highly decreased the elastic properties of FG by disrupting the intermolecular network. However, the disrupted network could not be recovered by reheating (85 °C) and cooling (25 °C) processes indicating it was non-reversible. It was also observed that FG of 0.4 wt% demonstrated the best stabilizing effect on the oil/water emulsion systems for the appropriate viscosity and weak-gel properties. The study aims to provide a full understanding of the rheological and emulsifying properties of high temperature extracted FG under different treating conditions with an intent to promote its application in the food and non-food industries.