Thermal-assisted synthesis of ferulic acid-chitosan complex in water and its application as safe antioxidant

Safe antioxidants are highly demanded in food preservation, yet existing preparation methods of typical bio-based antioxidants all suffer from either toxic catalysts or poor water solubility of the products. Herein, a water-soluble safe antioxidant, ferulic acid-chitosan complex, was facilely prepared in water with the assistance of mild-temperature heating. The chemical structure of ferulic acid-chitosan complex was determined by spectroscopy, and its thermal stability and rheological properties were studied in detail. Different from its precursors, the ferulic acid-chitosan complex exhibits much improved water solubility, thanks to its ionic structure. The as-prepared chitosan-ferulic acid complex displays higher antioxidative property than free ferulic acid, which was illustrated by the good preservation of freshly prepared apple juice. Such thermal-assisted synthesis strategy is demonstrated as an effective approach to prepare hydrophilic chitosan complex bearing hydrophobic organic acid, which enables great feasibility to the development of chitosan-based functional biomaterials.