(217af) Water Soluble Ferulic Acid Grafted Chitosan: An Antioxidant for Active Biodegradable Films

Chitosan is an amino polysaccharide mainly extracted from crab shells, shrimp shells and squid pens, which are solid wastes from seafood industries.  Chitosan has been applied in various applications including pharmaceutical, cosmetics, food and packaging industries owing to its general recognition as safe, excellent biodegradability and biocompatibility, as well as ability to form films, membranes, gels, beads, fibers and particles.  However, chitosan possesses strong inter- and intramolecular hydrogen bonds which limit its solubility in neutral pH water and most common organic solvents resulting in less utilization.  Chemical modification, e.g. substitution of some substances or grafting other polymers onto chitosan at hydroxyl and/or amino groups is an alternative way to impede hydrogen bond formation, or in other words to improve its solubility.  In addition, the obtained chitosan derivatives may possess novel functions depending on the introduced substances.  Bioactive phenolic compound bearing carboxyl group is a potential candidate for grafting onto chitosan due to its multifunctional properties such as combined antimicrobial and antioxidant activities.  Ferulic acid is one of the most effective natural phenolic antioxidants, which has been used in food, pharmaceutical and active packaging film applications.  Therefore, the present work aims to synthesize ferulic acid grafted chitosan and also to investigate its properties including water solubility and antioxidant property.  Ferulic acid grafted chitosan was synthesized through a carbodiimide-mediated coupling reaction.  The chemical structure of the ferulic grafted chitosan was clarified by FTIR, ¹H NMR and ninhydrin assay.  The derivative prepared by using the reaction temperature of 60 °C, reaction time of 3 h and mole ratio of chitosan to feruric acid of 1:1 possessed the highest ferulic acid substitution degree (0.37).  The resulting ferulic acid grafted chitosan could be soluble in water (1.3 mg/mL) due to its reduced crystalinity as compared with chitosan and also exhibited 90% greater radical scavenging activity than chitosan.  The utilization of ferulic acid grafted chitosan as an antioxidant for active biodegradable films has also been investigated and discussed.