The data accumulated so far bear witness to the film-forming ability of chitosan
and to its biological activities. Chitosan, a biodegradable food fiber, offers great potential
as an antifungal preservative for fresh fruit and vegetables. Detailed studies on
the permeability of chitosan films under high humidity to various gases and volatiles
are required in order to establish its ultimate potential applications as a coating for
harvested commodities. There are some indications in the literature of its unusual differential
permeability to gases as opposed to typical plastic films i.e., chitosan films
are more permeable to oxygen than to carbon dioxide. Above all, the antifungal and
eliciting activities of chitosan present exciting possibilities for crop protection. Its dual
activity gives chitosan great potential as an antifungal preservative for fresh horticultural
commodities. The physico-chemical and biological functionality of chitosan which
makes possible its diverse applications originate from its unique structure. Chitosan
polymeric nature confers to it a film-forming property. Its polycationic nature provides
the basis for its ability to interact with negatively charged biomolecules which
are responsible for its biochemical properties.