<P> Mutarotation is the change in the optical rotation because of the change in the equilibrium between two anomers, when the corresponding stereocenters interconvert . Cyclic sugars show mutarotation as α and β anomeric forms interconvert . The optical rotation of the solution depends on the optical rotation of each anomer and their ratio in the solution . </P> <P> Mutarotation was discovered by French chemist Dubrunfaut in 1844, when he noticed that the specific rotation of aqueous sugar solution changes with time . </P> <P> The α and β anomers are diastereomers of each other and usually have different specific rotations . A solution or liquid sample of a pure α anomer will rotate plane polarised light by a different amount and / or in the opposite direction than the pure β anomer of that compound . The optical rotation of the solution depends on the optical rotation of each anomer and their ratio in the solution . </P> <P> For example, if a solution of β - D - glucopyranose is dissolved in water, its specific optical rotation will be + 18.7 . Over time, some of the β - D - glucopyranose will undergo mutarotation to become α - D - glucopyranose, which has an optical rotation of + 112.2 . Thus the rotation of the solution will increase from + 18.7 to an equilibrium value of + 52.5 as some of the β form is converted to the α form . The equilibrium mixture is actually about 64% of β - D - glucopyranose and about 36% of α - D - glucopyranose, though there are also traces of the other forms including furanoses and open chained form . The α anomer is the major conformer, although somewhat controversially; this is due to the anomeric effect with the stabilisation energy provided by n - σ * hyperconjugation . </P>

Explain the concept of mutarotation in relation to disaccharides and polysaccharides