Production of Low Molecular Weight Chitosan Using a Combination of Weak Acid and Ultrasonication Methods

Abstract

Low molecular weight chitosan (LMWC) has higher solubility and lower viscosity allowing for a wider pharmaceutical application compared to high molecular weight chitosan. LMWC chitosan can be obtained through a chitosan depolymerization process. This research aimed to produce LWMC using the combination of formic acid and ultrasonication method with the optimal condition of the depolymerization process. The chitosan depolymerization method was performed by combining formic acid and ultrasonication. The optimum conditions of the depolymerization process were obtained using the Box–Behnken design. The LMWC obtained from depolymerization was characterized to identify its yield, degree of deacetylation, the molecular weight, structure, morphology, thermal behavior, and crystallinity index. Results: The characterization results of LWMC obtained from the depolymerization process using the optimum conditions showed that the yield was 89.398%; the degree of deacetylation was 98.076%; the molecular weight was 32.814 kDa; there was no change in the chemical structure, LWMC had disorganized shape, there was no change in the thermal behavior, and LWMC had a more amorphous shape compared to native chitosan. Conclusion: The production of LWMC involving depolymerization in the presence of weak acid and ultrasonication can be developed by using the optimal condition of the depolymerization process.

Keywords

• optimization
• low molecular weight chitosan
• depolymerization
• Box-Behnken Design