Mutarotation is the change in the specific optical rotation of a cyclic monosaccharide as it reaches an equilibrium between its
and
anomeric forms.
Example -
and
Glucose are two anomers which have different specific optical rotation which assumes an intermediate value when their mixture is left for a long time.
Anomers meaning :-If the OH group is on the right side ,it is called alpha glucose and if on left it is called beta glucose. when glucose is crystallised from water or aqeous alcohol at room temperature, alph glucose is obtained. but if it is crystallised at a temp above 371K it gives beta glucose.