• Applied Biological Chemistry
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• v.41 no.6
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• pp.442-446
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• 1998

Chitosan has been known to have an antimicrobial activity. Chitosan samples having different molecular weights were tested for the antimicrobial activity against Escherichia coli in a liquid medium and on the paper sheets coated with different types of chitosan samples. In a liquid medium, Chitosan A $(Mw\;3,000{\sim}5,000)$ and B $(Mw\;200,000{\sim}500,000)$ showed minimal inhibitory concentration (MIC) of 40 and $10\;{\mu}g/ml$, respectively. The MIC of chitosan C $(Mw\;500,000{\sim}1,500,000)$ was similar to that of chitosan B. The paper sheets coated with chitosan A, B, and C also showed growth inhibition against E. coli. As a typical agricultural product, strawberry was tested for the extension of shelf life by using the chitosan-coated packaging papers. Storage experiments showed that chitosan-coated packaging papers extended the shelf life of strawberry at the chilling temperature of $4^{\circ}C$.