Ice recrystallisation inhibition by polyols: comparison of molecular and macromolecular inhibitors and role of hydrophobic units

The ability of polyols to act as ice recrystallisation inhibitors (IRI), inspired by antifreeze (glyco)proteins are studied. Poly(vinyl alcohol), PVA, a known IRI active polymer was compared to a panel of mono and polysaccharides, with the aim of elucidating why some polyols are active and others show no activity. When corrected for total hydroxyl concentration all the carbohydrate-based polyols displayed near identical activity with no significant influence of molecular weight. Conversely, PVA was several orders of magnitude more active and its activity displays significant dependence on molecular-weight implying that its mechanism of action is not identical to that of carbohydrates. In a second step, the role of hydrophobicity was studied and it is observed that monosaccharide IRI activity is enhanced by alkylation. Dye-quenching assays demonstrated that PVA is able to present a hydrophobic surface without self-aggregation. Therefore, the ability to present a hydrophobic domain is hypothesised to be essential to obtain high IRI activity, which has many biotechnological applications.