Abstract
Supercooling-facilitating (anti-ice nucleation) substances, which are several flavonol glycosides and hydrolyzable tannin, are found in xylem parenchyma cells in trees to keep a liquid state of intracellular water to -40℃ in winter. It is gradually discovered that other associated compounds also have supercooling-facilitating activity in the solution containing ice-nucleating bacteria, Erwinia ananas. These supercooling-facilitating substances are expected to be used in real world application. However, for their applications, judging the supercooling activity not only by standard droplet freezing assay in solutions containing different kinds of ice nucleators but also by more practical methods using a large volume of solutions under shaking may be required. In this study, we measured the supercooling-facilitating activity of several kinds of flavonol glycosides and tannins by droplet freezing assay in solutions with various ice nucleators and by shaking assay in bulk solutions. It was revealed that supercooling activity of substances tested in this study varied according to measurement condition, such as types of ice nucleator, volume of solution, concentration of substances and the presence or absence of shaking.
