Preparation of oxidized agar and characterization of its properties.

A series of oxidized agars with different carboxyl content were prepared, and their properties were determined and analyzed. The results showed that the gelling temperature, the optical rotation and the apparent viscosity of the agar solution, and the melting temperature, the strength, the hardness, the fracturability, the springiness, the chewiness and the gumminess of agar gel all decreased except that the cohesiveness increased after oxidation. The gel skeleton structures of agar before and after oxidation were all of the porous network structures, but the pores of gel skeleton structure became smaller and denser after oxidation.