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Preparation of controlled release antimicrobial food packaging materials
In this study, potassium sorbate (Psb) incorporated cellulose acetate (CA) films were developed for antimicrobial food packaging applications. The most significant characteristics of these films were their asymmetric porous structure. To achieve appropriate controlled release of Psb, the structure of the films were changed by manipulating the initial casting composition, wet casting thickness, drying temperature and number of layers. The effectiveness of the films was tested through measurement of release kinetics and antimicrobial activity on selected microorganism, Penicillium commune. It was found that as the initial casting composition, wet casting thickness and drying temperature increase, porosity and pore size of the films reduce leading to slower release rates. The most significant parameter affecting the release was found as the number of layers. The diffusion coefficient of Psb through multilayer films decreased by two orders of magnitude compared with single layer. Drying-induced crystallization was observed in single layer films. Higher number and larger size of crystals were observed in more porous films. Fast initial release of Psb from the single layer films which is controlled by Fickian diffusion was followed by a decreasing release rate due to slow crystal dissolution. However, in multilayer films, release rate is regulated onl by diffusion of Psb through the film. All the films prepared showed growth inhibition on P. commune. The antimicrobial activities of single layer films were found higher than the multilayer films. The results of this study demonstrated that Psb incorporated CA films show promising potential for controlled release in antimicrobial packaging.