Maltitol is a disaccharide polyol (sugar alcohol) derived from maltose and widely used as a low-calorie sweetener with sucrose-like sensory properties but a reduced glycemic impact. It is extensively applied in food formulation and pharmaceutical products.
Chemical Structure
Maltitol (C₁₂H₂₄O₁₁; molecular weight 344.31 g/mol) consists of an α-D-glucopyranosyl unit linked via a 1→4 glycosidic bond to D-sorbitol (glucitol), chemically defined as 4-O-α-D-glucopyranosyl-D-glucitol. In its orthorhombic crystalline form, the molecule contains multiple hydroxyl groups, conferring high hygroscopicity and a specific optical rotation of approximately +105° (c = 10, H₂O). Unlike sucrose, maltitol lacks a reducing end due to the presence of the sorbitol moiety, which enhances thermal stability and prevents Maillard browning reactions.
Production Methods
Commercial maltitol is produced from high-maltose corn syrup obtained by enzymatic hydrolysis of starch using α- and β-amylases. The syrup is subsequently hydrogenated under high pressure (up to 200 bar) and elevated temperatures (100–150 °C) in the presence of Raney nickel or ruthenium catalysts. This process yields syrups containing more than 99% maltitol, which are further purified by ion-exchange chromatography, decolorization, and crystallization.
Physicochemical Properties
Maltitol exhibits very high water solubility (approximately 1750 g/L at 20 °C) and a sweetness intensity corresponding to 75–90% of that of sucrose. It has a melting point in the range of 144–152 °C and a very low vapor pressure (around 0.001 Pa at 20 °C). In aqueous systems, maltitol forms clear, viscous solutions that remain stable across a pH range of 3–7 and temperatures up to 150 °C. It is resistant to fermentation by oral microorganisms, rendering it non-cariogenic, and provides approximately 2.1 kcal/g due to partial absorption in the small intestine (about 40%) followed by fermentation in the colon. Its equilibrium relative humidity is comparable to that of sucrose, which helps prevent unwanted crystallization in confectionery products.
