Controlled release of nisin from HPMC, sodium caseinate, poly-lactic acid and chitosan for active packaging applications

Biodegradable polymers with distinct composition can be used as antimicrobial carriers. To judge their relative efficiency as antimicrobial carriers, release rates of fluorescently labeled nisin Z from hydroxypropyl methylcellulose (HPMC), chitosan (CTS), sodium caseinate (SC) and polylactic acid (PLA) films were evaluated at 4 and 40 degrees C in water-ethanol solution. Nisin diffusion coefficient (D) indicated that D-CTS < D-PLA < D-SC < D-HPMC. Temperature increase significantly increased nisin release from SC and HPMC films due to glass transition and hydrophilic nature. Partition coefficients (K) followed the same trend but were below 1, except for HPMC at 40 degrees C, which implies that, at equilibrium, a lower amount of nisin was liberated in water-ethanol solution. A higher antibacterial effect against Listeria monocytogenes CIP 82110 and Staphylococcus aureus CIP 4.83 was observed with HPMC and SC films containing nisin due to strong interactions (hydratation) between the medium and the film. However, HPMC, CTS, SC packaging films could progressively release nisin to sustain an anti-bacterial effect and can be favorably used for prolonging shelf life of packed food. (C) 2014 Elsevier Ltd. All rights reserved.