Reducing & Non-Reducing Sugars

Reducing Sugars: Possess a free hemiacetal/hemiketal $$\text{--OH}$$ group at the anomeric carbon; reduce Tollen's and Fehling's reagents (All monosaccharides, Maltose, Lactose).

Non-Reducing Sugars: Hemiacetal $$\text{--OH}$$ groups are tied up in glycosidic bonds (e.g., Sucrose).