EFFECTS OF SUGARS AND POLYOLS ON THE GEL SOL TRANSITION OF KAPPA-CARRAGEENAN GELS

The effects of various sugars and polyols, such as ethylene glycol, glycerol, ribose, glucose, fructose, mannose, galactose, sucrose, maltose and raffinose, on the gel-sol transition of kappa-carrageenan gels were studied by differential scanning calorimetry (DSC) in the present work. The melting temperature T(m) and the setting temperature T(s) were shifted to higher values with increasing concentration of the added polyol or sugar. This shift was linearly related with the dynamic hydration number or the number of equatorially attached hydroxyl groups in the added polyol or sugar. This suggests that the hydrogen bonding between hydroxyl groups in kappa-carrageenan and polyol or sugar is newly created, and that it stabilizes the structure of junction zones.