The antifungal activities of medium molecular weight chitosan and its
hydrosoluble derivative salt N,N,N-trimethylchitosan were examined as both
gel and as a solid protective coating against three common food spoilage
fungi (Penicilliumsp., wild Aspergillussp. and one standard strain of
Aspergillusflavus). The salt derivative is characterized by having permanent
positive charges and is expected to have a higher antimicrobial activity
than commercial chitosan. In gel form, the minimum inhibitory concentration
(MIC) resulted in the same value for both polymers against all tested fungi
(> 2.0 gl-1). The derivative presented a significant fungistatic action
against the Penicillium strain within the concentration range of 0.2 to 0.6
gl-1. When applied as protective coatings on freshly cut cherry tomatoes,
the commercial chitosan appeared to be more effective in forming stable
films and preventing fungal infestation than its derivative. Less than
20?25% of samples were infected after one week of incubation when compared
to control (uncoated) and chitosan treated samples.
Heterogeneity of food spoilage fungi
