The effect of antifreeze proteins and poly(vinyl alcohol) on the nucleation of ice: a preliminary study

Three substances have been tested for ice nucleation inhibition. These were an antifreeze protein AFP III from the fish Macrozoarces americanus, an antifreeze glycoprotein AFGP from the fish Dissostichus mawsoni, and an 80% hydrolysed poly(vinyl alcohol) with a molecular weight of 9 to 10 kD. A nucleation spectrometer was used to test nucleation inhibition at a range of concentrations against two types of ice nuclei: those present in tap water and a bacterial nucleator from Pseudomonas syringae. The PVA reduced the nucleation temperature of tap water and the bacterial dispersions at all the concentrations which were tested. The AFGP reduced the nucleation temperature of tap water but enhanced the nucleation activity of the bacterial nucleators. At low concentrations the AFP III reduced the nucleation temperature of both tap water and the bacterial nucleator. At high concentrations the AFP III enhanced the nucleation temperature of the bacterial nucleator and broadened the nucleation spectrum of the tap water to encompass the nucleation spread of the control. The possible mechanisms of nucleation suppression and enhancement are discussed.