Antimicrobial Films Based on Chitosan and Methylcellulose Containing Natamycin for Active Packaging Applications

Biodegradable polymers are gaining interest as antimicrobial carriers in active packaging. In the present study, two active films based on chitosan (1.5% w/v) and methylcellulose (3% w/v) enriched with natamycin were prepared by casting. The antimicrobial’s release behavior was evaluated by immersion of the films in 95% ethanol (v/v) at different temperatures. The natamycin content in the food simulant was determined by reversed-high performance liquid chromatography with diode-array detection (HPLC-DAD). The apparent diffusion (DP) and partition (KP/S) coefficients were calculated using a mathematical model based on Fick’s Second Law. Results showed that the release of natamycin from chitosan based film (DP = 3.61 × 10−13 cm2/s) was slower, when compared with methylcellulose film (DP = 3.20 × 10−8 cm2/s) at the same temperature (p < 0.05). To evaluate the antimicrobial efficiency of active films, cheese samples were completely covered with the films, stored at 20 °C for 7 days, and then analyzed for moulds and yeasts. Microbiological analyses showed a significant reduction in yeasts and moulds (7.91 log CFU/g) in samples treated with chitosan active films (p < 0.05). The good compatibility of natamycin with chitosan, the low Dp, and antimicrobial properties suggested that the film could be favorably used in antimicrobial packagings.