Extraction of chia seed mucilage: Effect of ultrasound application

Abstract

Chia seed mucilage is an ingredient with high potential as a natural thickener for food, cosmetic, and pharmaceutical applications. In this work, a chia mucilage enriched in the insoluble fraction was cold extracted using different stirring times and ultrasound application, followed by a centrifugation step. The processes employed in the mucilage extraction are according to the green approach and no organic solvent was used in a further step of purification. The results demonstrated a yield of around 3.7% and extracts with 75% carbohydrates on average. As the mucilage was enriched in the insoluble fraction, the microstructure images showed a high amount of fibrillar structures that tended to form denser aggregates with the application of ultrasound. Thermal analyzes indicated that mucilage could resist industrial processes, and its thermal stability increased with ultrasound application. Samples showed shear-thinning behavior and the apparent viscosity at 100 s−1 was between 57 and 280 mPa∙s An increase of stirring or sonication time led to a reduction of the apparent viscosity and elastic behavior, which could be related to carbohydrate concentration and the organization of fibrillar structure. Thus, desired rheological properties can be achieved by changing the extraction conditions.