A facile quantitative characterization method of incomplete degradation products of galactomannan by ethanol fractional precipitation

A novel method for the quantitative characterization of incomplete degradation products of galactomannan (IDPG) was developed by ethanol fractional precipitation. In this work, IDPG in the enzymatic hydrolyzate of Sesbania cannabina galactomannan was fractionated into several fractions with high recovery (>96 %) by ethanol fractional precipitation. The average molecular weights of obtained fractions were in descending order with varied corresponding contents of galactomannan degradation products. Thus, the quantitative characterization of IDPG can be achieved. Moreover, the results of statistical validation and method robustness showed that the method has good reproducibility. Surprisingly, when this method was applied to the guar gum or locust bean gum enzymatic hydrolyzates, it was found that the lower the mannose to galactose ratio of un-hydrolyzed galactomannan, the higher the molecular weight of their degradation product obtained under same ethanol concentration. This method is effectively applied to the quantitative characterization of IDPG from other sources.