Inhibition of Ice Growth and Recrystallization by Zirconium Acetate and Zirconium Acetate Hydroxide

Abstract

The control over ice crystal growth, melting, and shaping is important in a variety of fields, including cell and food preservation and ice templating for the production of composite materials. Control over ice growth remains a challenge in industry, and the demand for new cryoprotectants is high. Naturally occurring cryoprotectants, such as antifreeze proteins (AFPs), present one solution for modulating ice crystal growth; however, the production of AFPs is expensive and inefficient. These obstacles can be overcome by identifying synthetic substitutes with similar AFP properties. Zirconium acetate (ZRA) was recently found to induce the formation of hexagonal cavities in materials prepared by ice templating. Here, we continue this line of study and examine the effects of ZRA and a related compound, zirconium acetate hydroxide (ZRAH), on ice growth, shaping, and recrystallization. We found that the growth rate of ice crystals was significantly reduced in the presence of ZRA and ZRAH, and that solutions containing these compounds display a small degree of thermal hysteresis, depending on the solution pH. The compounds were found to inhibit recrystallization in a manner similar to that observed in the presence of AFPs. The favorable properties of ZRA and ZRAH suggest tremendous potential utility in industrial applications.

Surface stiffening and enhanced photoluminescence of ion implanted cellulose – polyvinyl alcohol – silica composite

“…The control of ice nucleation is essential to engineer the porous morphology of the scaffolds. The antifreezing substances such as anti freezing proteins and salts like zirconium acetates are the important class of materials which controls the ice nucleation by the exposure of hydrophobic residues on ice nuclei (Duman, 2015;Mizrahy, Dolev, Guy, & Braslavsky, 2013). The pore structure is mainly controlled by the ice nucleation, which is influenced by various parameters such as solution viscosity, concentration of the solute, growth velocity of ice crystals and pH.…”

Controlling the Freezing Process with Antifreeze Proteins

“…In theory, both PVA (Knight et al, 1995) and ZrA/ ZrAH (Mizrahy et al, 2013) mimic the structure of the ice-binding domain found in naturally occurring AFPs for ice crystal recognition. The mode of action found in these chemical alternatives is likely different from AFPs, because both substances can create gel-like phases that are able to envelope ice crystals.…”

“…Initially, recrystallization was not given much attention in the context of AFPs, but more recentlydand especially in relation to AFPs as an additive to fooddit has become an important factor in research (Zhang et al, 2007a,b;Regand and Goff, 2006;Crilly et al, 2008;Hightower et al, 1991;Mizrahy et al, 2013).…”

“…The end result is a three-dimensional patchwork of ice crystals with different orientations (Mizrahy et al, 2013). To the naked eye, ice does not give the impression of being a dynamic state of water.…”

“…However, researchers are generally looking for chemical compounds that prevent recrystallization (Gibson, 2010). Two such compounds are zirconium acetate (Mizrahy et al, 2013) and poly(vinyl alcohol) (PVA) (Knight et al, 1995;Congdon et al, 2013).…”