Esterification of Sesbania Gum Hydrolysate in Ionic Liquid, Optimization and Characterization of Its Derivatives

The goal of this work focuses to optimize some parameters in esterification process of sesbania gum hydrolysate by response surface methodology, and to characterize sesbania gum and its derivatives. The experimental results indicated that degree of substitution (DS) of maleate enzymolysis sesbania gum (MESG) could reach a value of 0.768 when an ionic liquid, that is, 1-butyl-3-methylimidazolium chloride, was used as a solvent during the esterification. The obtained regression model could well evaluate the synthesis of MESG. The stretching vibration peak of C–H bonds in MESG was split into two peaks at the wave numbers of 3937 and 2886 cm−1 owing to high DS. The esterification almost changed the crystalline structure of MESG into an amorphous one, whereas the enzymatic hydrolysis less affected the crystalline structure of sesbania gum (SG). The structure of SG granules was severely destroyed by such an esterification with an ionic liquid. The esterification increased the thermal stability of SG. Adding MESG could obviously influence the potato starch pasting characteristics such as peak viscosity, trough viscosity, final viscosity, setback and breakdown.