Supercooling enhancement by adding antifreeze protein and ions to water in a narrow space

The control of ice crystal growth has been an important issue in various fields, such as the quality maintenance and improvement of food texture in frozen food, and the storages of tissues and organs in hospitals. The temperatures at ice/solution interfaces were measured with a small thermocouple. The concentration of antifreeze protein was estimated by fluorescence microscopy, and the concentration of permanganate ion was measured from the intensity of transmitted light. It was found that the depression of interface temperature (defined as the difference between the interface temperature of the solution and that of pure water) of the mixed solution was much lower than the sum of the depression of the interface temperatures of two solutions of single solute. High concentration regions of the protein in the bottom-edge region deteriorate the diffusion of ions. This is reason for the deterioration of the depression of interface temperature due to an increase in the interface velocity in the cases of mixed solutions.