Carboxymethyl cellulose-based nanocomposites reinforced with montmorillonite and ε-poly-l-lysine for antimicrobial active food packaging

Traditional packaging materials with single function or weak activity cannot meet the requirements of active packaging. In this study, antimicrobial carboxymethyl cellulose (CMC)-based nanocomposites containing montmorillonite (MMT) and epsilon-poly-(l-lysine) (epsilon-PL) were prepared by solution casting method. The morphological, optical, mechanical, barrier, thermal, and antimicrobial properties of the resulted ternary nanocomposites were investigated. The surface morphology of the films was dependent on the contents of the epsilon-PL used. The incorporation of MMT and epsilon-PL into CMC matrix improved the UV barrier property, tensile strength, hydrophobicity, and water vapor barrier property. When incorporation of 7.5 wt % epsilon-PL, the tensile strength increased more than threefold and the water vapor permeability decreased by about 35% compared with pure CMC film, the water contact angle reached up to the highest value of 65.38 degrees. The epsilon-PL incorporated CMC/MMT films exhibited good antimicrobial activities against Gram-positive (Staphylococus aureus) and Gram-negative (Escherichia coli) bacteria and fungi (Botrytis cinerea and Rhizopus oligosporus). Microbial growth inhibition rate of above 90% was obtained when the content of epsilon-PL got up to 7.5 wt %. In addition, CMC/MMT/epsilon-PL7.5 wt % film-forming solution having the appropriate properties was used as coating for the strawberries preservation, the shelf life of strawberries was extended for 2 days. (c) 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 137, 48782.