抄録
Crystalline sugars are significant commodities in the world market, however the crystallization behaviour of many sugars is still not well known. Recently it has been shown that the mutarotation reaction of reducing sugars plays a significant role in determining the crystallization rate of these sugars, and thus it is beneficial to be able to model and predict mutarotation rates for common sugars. The mutarotation rate and equilibrium of simple carbohydrates; D-glucose, D-galactose, D-cellobiose, D-maltose, and D-turanose, in aqueous solutions were measured between 7 and 35°C, using 13C-NMR. The effects of sugar concentration and temperature on the rate of mutarotation and mutarotation equilibrium were observed. It has been found that the rate of mutarotation slightly decreases as the sugar concentration increases. The rate constant of the studied sugars follows an Arrhenius relationship with respect to temperature, and activation energies for the reactions were found from an Arrhenius plot. There are no clear correlations between the equilibrium constant and the sugar concentration or the temperature. Finally, it is quite clear that the mutarotation rate of ketose sugars is higher than the mutarotation rate of aldose sugars, and the number of rings in the structure (i.e. monosaccharide and disaccharide) does not have a significant effect on the rate of mutarotation.
