Preparation, characterization and antibacterial activity of water-soluble O-fumaryl-chitosan

A novel water-soluble chitosan derivative, O-fumaryl-chitosan (OFCS), was prepared by using the selective partial acylation of chitosan and fumaric acid in the presence of H2SO4. The chemical structure and physical properties of OFCS were characterized by FTIR, 1H NMR, 13C NMR, and TG techniques. Our results showed that the degree of substitution (DS) for the chitosan derivatives was from 0.07 to 0.48 and the prepared derivatives had good solubility over a wide pH range, for example, the solubility of OFCS increased from 10.5 to 52.6 mg/ml as the DS increased. The antibacterial activity of chitosan and OFCS was investigated against Escherichia coli and Staphylococcus aureus. The results indicated that the antibacterial activity of OFCS was much stronger than that of chitosan and it increased with increasing DS increasing. These findings suggest that the OFCS with a DS of 0.48 is preferable for use as a food preservative.