Sugar and polyol solutions as effective solvent for biopolymers

Ternary mixtures of biopolymers, sugars or polyols and water can be treated as a pseudo binary system with respect to melting of the biopolymer. Sugar and polyol solutions can be treated as an effective solvent, characterized by the density of hydroxyl groups available for intermolecular hydrogen bonding. Such a treatment has been shown earlier for the glass transitions of the ternary mixtures. Now we have analysed the melting behaviour of biopolymers in these ternary mixtures. If the melting points are plotted as function of the density of hydroxyl groups, all data for a variety of sugars and polyols collapse to a single curve. This master curve coincides with the prediction of the melting line for biopolymer/water mixtures as follows from Flory's theory. Such behaviour has been found for starch, gelatin, soy and sunflower proteins.