Ice recrystallization in sucrose solutions stored in a temperature range of - 21°C to - 50°C

Abstract

The recrystallization of ice crystals in sucrose solution was investigated by cryo-SEM in a temperature range of - 21°C to - 50°C, including temperatures around Tg′. By using the technique of image analysis, the mean radius of the ice crystals was evaluated and recrystallization rates were calculated by a kinetic equation based on the Ostwald ripening principle. As the storage temperature decreased, a rapid decline in recrystallization rate was observed between - 29°C and - 35°C, which was consistent with the concept of glass transition of the freeze-concentrated matrix. Even at - 50°C, at which the freeze-concentrated matrix was considered to be in glassy state, an increase in the mean crystal size was observed after 20 hr storage.