what is mutarotation?
Mutarotation is the spontaneous change in the specific rotation of the optically active compound with time till the equilibrium value.
so, in the solution , the alpha D glucose and beta D glucose exists in the equilibrium as under:-
∝ D glucose ↔ open chain form ↔ β D glucose
sp. rotation sp. rotation sp. rotation
= + 111° + 52.5° + 19.2 °
of equilibrium mixture