Abstract: Chitosan p-hydroxybenzote could inhibit the growth of all the bacteria and fungus tested. The minimum inhibitory concentrations (MICs) of chitosan p-hydroxybenzoate for S.aureus and E.coli respectively are 0.01% and 0.025%. Chitosan p- hydroxybenzoate shows strong antimicrobial effect at a wide pH range (pH4～8). Because of the existence of free amino group on chitosan unit. The antimicrobial activity of the ester in acid solution is superior to that in basic solution. The ester shows good heat-stability. In food systems such as apple juice and meat extrude, chitosan p-hydroxybenzoate still behaves strong antimicro- biala ctivity.

Key words: chitosan p-hydroxybenzoate, MICs, antimicrobial activity