Molecular and microstructural properties of functional behavior of particles from size-fractionated Durvillaea antarctica powders.

This study investigates seaweed powder (SP) from D. antarctica, including cortex (CSP) and medulla (MSP) structures, separated into four size ranges (μm): <75 (SP1) to 425 (SP4), dispersed in a 4.8% solution, and heated to 25-80 °C. Analyses of particle size, FT-IR, SEC, zeta potential, SEM, rheology, and tribology explored structure-property relations. FT-IR identified alginates, fucoidans, and laminarin (1460-850 cm-1), with molecular weights from 5 to 400 kDa. SEM revealed D. antarctica's rough cortex and smooth medulla with thin fibers and long cells. Cell wall disruption promoted SP swelling up to 3 times, impacting functionality. SP suspensions and supernatants showed shear-thinning and higher viscosity above 40 °C. SP1-SP2 behaved as gel-like (G' > G"), possibly by increased alginate release. SP3-SP4 (G" > G'), aid particle exclusion and lubrication. Temperature influences SP lubrication, decreasing friction and forming a viscosity-dependent film. Bi-composite SP-powders enable size-dependent thickening and lubrication, releasing polysaccharides as a sustainable alternative to purified hydrocolloids targeting oral-processing behavior.