A Simple Method for Isolation of Polymannuronate and Polyguluronate from Alginate Hydrolyzed by Organic Acids

Abstract

Molecular weights of alginates hydrolyzed with organic acids ranged from 7.5 to 53.2 kDa. There was no significant difference in the molar ratio of mannuronate to guluronate in alginates hydrolyzed with organic acids. Acetic acid was found to be the most effective organic acid for hydrolysis of alginate.The MW of alginate decreased with increasing concentration and reaction time with acetic acid as a hydrolyzing agent. The correlations between the MW of hydrolyzed alginate and concentration of acetic acid as well as reaction time with 0.4 M acetic acid were plotted and the relevant equations obtained in this study. Polymannuronate and polyguluronate were isolated by pH adjustment of alginate hydrolyzed with 0.4 M acetic acid. The molar percentages of mannuronate in polymannuronates isolated from alginate hydrolyzed with 0.4 M acetic acid at 100 o C were increasing in proportional to the reaction time such as 75% for 1 hr, 90% for 3 hr, and 98% for 5 hr of reaction time.