Influence of molecular weight of an anionic marine polysaccharide (sulfated fucan) on the stability and digestibility of multilayer emulsions: Establishment of structure-function relationships

摘要

The ability of sulfated fucan to fabricate stable multilayer emulsions has been established in previous studies, but the structure-function relationships governing the formation of these structured emulsions are still poorly understood. In this study, sulfated fucan was extracted from sea cucumber and degraded to different molecular weights (2000-100 kDa) by enzyme hydrolysis. The stiffness and dimensions of the polysaccharides produced decreased as the molecular weight (M-w) was reduced. The impact of the M-w of the fucans on the characteristics of protein-stabilized emulsions was investigated by particle size, zeta-potential, and creaming stability analysis. All the fucans adsorbed to caseinate-coated droplet surfaces from pH 5 to 3 and protected the droplets from aggregation by a combination of steric and electrostatic repulsion. The fucan with the higher M-w saturated the droplet surfaces at a lower concentration. Moreover, multilayer emulsions fabricated from the highest M-w fucan were more resistant to NaCl addition (0-100 mM) and gave better long-term stability. The sulfated fucans with higher molecular weights (2000-600 kDa) could significantly increase the initial digestibility rate of the encapsulated lipid. These results show that the M-w and conformation of sulfated fucans impacts the stability and digestibility of multilayer emulsions, thus providing guidance for the further application of anionic polysaccharides in preparing multilayer emulsions.