Abstract
The freeze concentration processes of agarose gels with or without sucrose were observed using a Cryo-SEM and a light microscope for the purpose of understanding the behavior of a polymer network and a sucrose solution in its gel during the freezing processes. Furthermore, whether the polymer network and a sucrose solution in the frozen gels are in a crystalline state or a glassy state was investigated using differential scanning calorimetry (DSC). As a result, it was suggested that the polymer network during freezing is assembled, like a membrane, on the overall surface of ice crystals. However, the diffusion of water is thought to be not very inhibited by the membranes because the ice crystals grew very fast and the form of ice crystals became polygonal. Such behavior of the polymer network itself was independent of the presence of sucrose. The sucrose molecules added to the gel affected the ice crystal growth in the gel in the same way as in the case of a sucrose solution. The results of the DSC measurement indicated that only the sucrose solution in the gel turns into a glassy state.
