Effect of Low-Molecularization on Rheological Properties of Alginate

Partial hydrolyzing condition for low-molecularized alginate and rheological properties such as viscosity, solubility, emulsitying ability, oil absorption capacity, bile acids binding and metal ion binding of the low-molecularized alginates from the sea mustard ( Undaria pinnatifida) and giant kelp (Macrocystis pyrifera) were investigated. Alginate from sea mustard was regularly hydrolyzed with the increase of HCl concentration in the range of 0.2 N to 0.5 N and with the prolonged reaction time at . The molecular weight of alginate was decreased to a part of 100 after hydrolysis for 50 min with 0.3 N HCl. The ratio of mannuronate to guluronate was increased with the acid hydrolysis and total yield was estimated to be . Low-molecularization of alginate was featured in the apparent decrease of viscosity, whereas solubility, emulsifying ability, and bile acids binding ability were increased with the low-molecularization. Oil absorption capacity of the acidalkali soluble alginate was slightly higher than that of the water soluble alginate. Metal ion binding capacity was the highest in acidalkali soluble alginate, and decreased with the low-molecularization.