73D-2 |
The antimicrobial films based on Na-alginate and K-carrageenan |
J. H. CHOI, D. S. Cha, and H. J. Park. Graduate School of Biotechnology, Korea University, 5Ka Anam-Dong, Sungbuk-Ku, Seoul, 136-701, South Korea The use of natural hydrophilic polymers as film materials has received considerable attention in the last few years, especially from the viewpoint of cost, environmental and safety issues. Alginates are salts of alginic acid isolated from brown seaweeds and K-carrageenan is structural polysaccharide obtained from the red seaweed abundantly. Food-grade antimicrobial agents (lysozyme, nisin, grape fruit seed extract and EDTA) incorporated with Na-alginate and K-carrageenan films can be used effectively in a wide range of food packaging. Our objectives were a) to produce biodegradable biopolymer film with food–grade antimicrobial agents b) to measure the mechanical properties of the film for industrial uses. Na-alginate or K-carrageenan based film solutions were prepared with PEG and glycerin as plasticizers (0.75%w/w) in distilled water and heated 70°É for 30min. Individual and combination of 20mM EDTA, 50§¶/§¢ nisin and 0.1% lysozyme were added to the Na-alginate or K-carrageenan solution. The agar diffusion test was used to determine the antimicrobial effect of the films on microorganism (Listeria innocua, Escherichia coli, Salmonella enteritidis, Staphulococcus aureus, Micrococcus luteus). Antimicrobial activities of films were assayed using the seeded lawn overlay spot assay. Film tensile strength and elongation at break were determined with an Instron. Na-alginate film exhibited larger inhibitory zone as compare to K-carrageenan film when the same levels of antimicrobial agents were incorporated. Among antimicrobial agents used, combination of GFSE and EDTA filled-film showed strong inhibition activities on all indicator strain including E. coli and S. aureus. Tensile strength and elongation of the antimicrobial films were weaker than the control. Among them GFSE-incorporated films showed a very low value. The biodegradable food-grade antimicrobial films prepared in this study showed a great potential for commercial application in packaging of processed foods such as surumi and tofu.
Session 73D, Food Packaging
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