Anomerization is the process of conversion of one anomer to the other. For reducing sugars, anomerization is referred to as mutarotation and occurs readily in solution and is catalyzed by acid and base. This reversible process typically leads to an anomeric mixture in which eventually an equilibrium is reached between the two single anomers.
The ratio of the two anomers is specific for the regarding sugar. For example, regardless of the configuration of the starting -glucose, a solution will gradually move towards being a mixture of approximately 64% β--glucopyranoside and 36% of α--glucopyranose. As the ratio changes, the optical rotation of the mixture changes; this phenomenon is called mutarotation.