Detection of the Metastable Ice Phase During Water Crystallization

BACKGROUND: Under atmospheric pressure, the identifiable phases of ice crystals are hexagonal (stable) and cubic (metastable). OBJECTIVE: This study aimed to test the hypothesis that water crystallizes into the cubic phase at the beginning and then changes to the hexagonal phase. MATERIALS AND METHODS: Aqueous solutions of 40% (w/w) and 50% (w/w) glucose, and 40% (w/w) ammonium hydrogen sulfate, as well as emulsified water, were investigated. RESULTS: The cubic-to-hexagonal ice phase transition was detected in 40% (w/w) glucose solution within a 1 s integration interval, whereas the cubic ice formed in 50% (w/w) glucose solution did not transition to the hexagonal phase. The cubic phase was also confirmed in the 40% (w/w) ammonium hydrogen sulfate solution, but not in emulsified water. CONCLUSION: The cubic-to-hexagonal ice phase transition was detected in three aqueous solutions tested upon freezing. It was not possible to clearly capture the transition process in emulsified water under the study condition.