Viscoelasticity of chia (Salvia hispanica L.) seed mucilage dispersion in the vicinity of an oil-water interface

Mucilage from chia (Salvia hispanica L.) seed contains carbohydrate polymers with high solubility. It forms highly viscous solutions at low concentrations, and possesses the ability to adsorb at interfaces because of the small amount of protein it contains (similar to 4.0%). The aim of this work was to study the viscoelastic properties of chia seed mucilage to gain insights regarding the formation structures at the oil-water interface and in the vicinity of the aqueous bulk phase. The rationale was that emulsions with enhanced viscoelastic properties at the vicinity of the interface are more likely to resist instabilities in the face of shear stress disturbances and exhibit long-term viability and stability. A constant shear stress was applied at the oil-water interface and at different distances from it, leading to underdamped inertio-elastic oscillations. It was found that the viscous and elastic moduli decreased and the inertia increased as the oil-water interface was approached from the aqueous phase. The results are discussed in terms of the possible stratification of the mucilage material at the oil-water interface. (C) 2015 Elsevier Ltd. All rights reserved.