The addition of sugars or polyols can improve the thermostability of enzymes by inducing changes in their microenvironments [35]. The protective effect of polyols is linked to their hydroxylgroups. The addition of certain polyols prevents the denaturation of enzyme molecules by enhancing hydrophobic interactions within protein molecules. In fact, the thermal stability improvement induced by the addition of polyols could presumably be attributed to the reinforcement of hydrophobic interactions within the enzyme molecules, which became more resistant to heat inactivation [36].