Structural characterization and physical ageing of mucilage from chia for food processing applications

Chia seed mucilage represents an emerging resource in food industry due to its particular tetrasaccharide (repeating unit) composition. In this investigation, we report on the effect of biomacromolecule concentration and ageing on the structural integrity of chia mucilage-based hydrogel networks. Hydrogels were produced with different polymer concentration and analyzed as prepared and after 10 days of ageing. Structural studies were undertaken through scanning electron microscopy, rheology and small angle X-ray scattering (SAXS). Rheological characterization revealed that ageing acts as destabilizing factor for hydrogel architecture. Indeed, hydrogel strength as well as viscosity were found to decrease upon ageing. This behavior related with a structural change was validated by microscopy. Strikingly, the formation of less entangled and packed meshwork was evidenced. SAXS elucidated that the mesh size of the hydrogel network increased with ageing. Overall, the ageing information provided in this study has to be taken into account when using chia mucilage as a food ingredient or in other application fields.