(651f) Release Kinetics of Nisin from Chitosan-Alginate Complex Films

Understanding the release kinetics of antimicrobials from polymer films is important in the design of effective active packaging films that can increase food safety and shelf-life. The release kinetics of nisin from chitosan-alginate complex films prepared using various fractions of alginate (33, 50 and 66%) were investigated into an aqueous release medium. Films containing higher alginate fractions showed significantly lower degree of swelling in water. The total amount of nisin released from films decreased significantly with an increase in alginate concentration. The mechanism of diffusion of nisin from all films was found to be Fickian, and diffusion coefficients varied from 0.872 x 10^-9 to 8.034 x 10^-9 cm²/s. Strong complexation was confirmed between chitosan and alginate polymers within the films using isothermal titration calorimetry and viscosity studies, which affects film swelling and subsequent nisin release. Complexation was also confirmed between nisin and alginate, which limited the amount of free nisin available for diffusion from films. These low-swelling biopolymer complexes have potential to be used as antimicrobial packaging films with sustained nisin release characteristics.