Preparation, characterization, and antimicrobial activity of chitin nanofibrils reinforced carrageenan nanocomposite films

Present study illustrates the preparation of chitin nanofibrils (CNF) reinforced carrageenan nanocomposite films by the solution-casting technique. CNF was prepared by acid hydrolysis of chitin, followed by high speed homogenization and sonication. FTIR result demonstrated that the chemical structure of chitin had not changed after acid hydrolysis. However, the crystalinity of CNF was found to be higher than chitin. The crystallite size of chitin and CNF was 4.73 and 6.27 nm, respectively. The char content at 600 °C of chitin (19.2%) was lower than the CNF (25%). The carrageenan/CNF composite films were smooth and flexible and the CNF was dispersed uniformly in the carrageenan polymer matrix. The tensile strength and modulus of carrageenan film were increased significantly (p < 0.05) after CNF reinforcement with up to 5 wt%, however, elongation at break, water vapor permeability, and transparency decreased slightly. Carrageenan/CNF nanocomposite films showed strong antibacterial activity against a Gram-positive food-borne pathogen, Listeria monocytogenes.