Role of water activity on the nucleation and growth of ice crystals in aqueous liquid of NaCl, glucose, and konjac glucomannan

Abstract

The microscopic mechanisms by which solutes influence ice crystal nucleation and growth in aqueous systems are fundamental to controlling freezing in various food and biological contexts. While the understanding of the initiation mechanism of pure water freezing is becoming increasingly clear, the mechanisms of ice nucleation and growth in hydrophilic colloids, such as polysaccharide dispersions, still rely on theoretical speculation and empirical assumptions. In this study, we experimentally demonstrated that polysaccharides regulated water freezing by affecting the water activity in the liquid phase. Konjac glucomannan (KGM) complicated the formation of critical ice nuclei, lowered the nucleation temperature, and shortened the ice crystal growth time by reducing water activity (aw) and altering the state of water within the system. The ice crystal growth for solution systems depended not only on freezing conditions but also on aw. Furthermore, by combining polarized light imaging with MATLAB data analysis, we conducted a comparative analysis of the differences in optical property changes during ice crystal growth between KGM dispersion and other solutions.