A carbohydrate exists in a cyclic or an acyclic form. During cyclization, the carbonyl carbon of monosaccharide transforms into a new stereocenter. Cyclization causes the formation of 2 new diasteriomers. They differ in the position of the attachment of a certain group to the new stereocenter. The new stereocenter is referred to as the anomeric carbon.
In the given problem, there are two monosaccharides such as glucose and fructose in the given disaccharides.
When fischer formula of these monosaccharides turns into cyclic stucture and form anomeric carbon.
How to locate the anomeric carbon in D-Glucose?
Step 1: Locate the oxygen inside the ring
Step 2: Look at the carbons on either side of the oxygen. One will be attached to a CH2OH group. Do not focus on this one. The carbon on the other side is the anomeric carbon.