Studies on supercooling-promoting substances (SCPSs) are reviewed introducing name of chemicals, experimental conditions and the supercooling capability (SCC) in all, so far recognized, reported SCPSs and results of our original study are presented in order to totally show the functional properties of SCPSs which are known in the present state. Many kinds of substances have been identified as SCPSs that promote supercooling of aqueous solutions in a non-colligative manner by reducing the ice nucleation capability (INC) of ice nucleators (INs). The SCC as revealed by reduction of freezing temperature (°C) by SCPSs differs greatly depending on the INs. While no single SCPS that affects homogeneous ice nucleation to reduce ice nucleation point has been found, many SCPSs have been found to reduce freezing temperatures by heterogeneous ice nucleation with a large fluctuation of SCC depending on the kind of heterogeneous IN. Not only SCPSs increase the degree of SCC (°C), but also some SCPSs have additional SCC to stabilize a supercooling state for a long term to stabilize supercooling against strong mechanical disturbance and to reduce sublimation of ice crystals. The mechanisms underlying the diverse functions of SCPSs remain to be determined in future studies.
Keywords: Anti-ice nucleation substance; Antifreeze proteins and glycoproteins; Droplet freezing; Emulsion freezing; Freezing of water; Heterogeneous ice nucleation; Homogeneous ice nucleation; Polyphenols; Supercooling-promoting substance.