Maltitol is made by extracting starch from crops like corn, wheat, or potatoes, breaking that starch down into maltose (a simple sugar), and then chemically converting the maltose into a sugar alcohol through a process called hydrogenation. The entire production chain transforms a common agricultural starch into a reduced-calorie sweetener that provides about 90% of sugar’s sweetness at roughly half the calories.
Step 1: Extracting Starch From Crops
Production starts with starch-rich crops. Corn is the most common source worldwide, but wheat and potatoes are also used depending on regional availability and cost. The starch is separated from the plant material through wet milling, a process that breaks kernels or tubers apart and washes out the pure starch granules. This starch is a long chain of glucose molecules linked together, and it serves as the raw material for everything that follows.
Step 2: Breaking Starch Into Maltose
Starch molecules are far too large to convert directly into maltitol, so manufacturers use enzymes to chop them into smaller pieces. The target molecule is maltose, a sugar made of just two glucose units linked together.
Several enzymes work in sequence to accomplish this. Alpha-amylase first breaks the long starch chains into shorter fragments. Then beta-amylase takes over, snipping pairs of glucose units (maltose) off the ends of those fragments. Beta-amylase alone can’t fully break down starch, though, because starch has branching points it can’t get past. A debranching enzyme called pullulanase is added to clip those branch points open, giving the beta-amylase access to more of the chain. The result is a high-maltose syrup, a concentrated liquid rich in the two-unit sugar that will become maltitol.
Step 3: Hydrogenation Turns Maltose Into Maltitol
This is the step that actually creates maltitol. The maltose syrup is placed in a high-pressure reactor along with hydrogen gas and a nickel-based catalyst (known in the industry as Raney nickel). Under these conditions, hydrogen atoms are forced onto the maltose molecule, converting one of its glucose units into sorbitol. The final product is a hybrid molecule: one glucose unit bonded to one sorbitol unit.
The reaction works best at moderate temperatures, no higher than about 130°C (266°F), with hydrogen pressure above 7 MPa (roughly 1,000 psi) and a near-neutral pH around 6.5. At the molecular level, the maltose ring opens up and exposes a reactive spot that the nickel catalyst helps hydrogen attach to. Keeping the temperature moderate is important because higher heat can drive unwanted side reactions that reduce the purity of the final product.
Step 4: Purification and Final Form
After hydrogenation, the crude maltitol solution contains the target sweetener along with small amounts of other sugar alcohols and residual sugars. The nickel catalyst is filtered out, and the solution typically passes through ion-exchange columns that strip away minerals, color compounds, and other impurities. The purified liquid can then take one of two commercial paths.
Maltitol syrup is simply concentrated to the desired thickness and sold as a viscous liquid. It often contains 50 to 80% maltitol along with other hydrogenated sugars, which makes it useful in candy, chocolate coatings, and baked goods where moisture and texture matter. Crystalline maltitol requires further concentration and carefully controlled cooling so that pure maltitol crystals form and can be separated from the remaining liquid. The crystals are dried into a white powder that looks and behaves much like table sugar, making it popular for hard candies, chewing gum, and tabletop sweetener packets.
Why the Process Matters for Nutrition
The hydrogenation step is what gives maltitol its distinct nutritional profile. By converting part of the sugar molecule into a sugar alcohol, the body can no longer digest and absorb it as efficiently as regular sugar. The FDA assigns maltitol a caloric value of 2.1 calories per gram, compared to 4 calories per gram for sucrose. That conversion also makes maltitol largely resistant to oral bacteria, which is why it shows up so often in “sugar-free” dental products.
The tradeoff is digestive. Because your small intestine only partially absorbs maltitol, a significant portion reaches the large intestine where gut bacteria ferment it. This fermentation produces gas and draws water into the colon, which can cause bloating, cramping, and diarrhea if you eat too much. Most people tolerate small amounts without problems, but sensitivity varies widely from person to person. Products containing maltitol are required in many countries to carry a label warning about potential laxative effects.
Syrup vs. Crystalline: What’s Different
The two commercial forms of maltitol come from the same production line but diverge at the purification stage. Crystalline maltitol is nearly pure, typically 98% or higher maltitol content. It dissolves cleanly, measures like sugar, and works well in applications where precise sweetness and a dry texture are needed. Maltitol syrup is less pure but more versatile. The mix of sugar alcohols it contains helps prevent crystallization in candies and provides a smooth mouthfeel in chocolate. The syrup form also tends to have a somewhat higher glycemic impact than the crystalline powder because of those additional hydrogenated sugars in the mix.
For food manufacturers, the choice between the two comes down to the product. A sugar-free chocolate bar benefits from the syrup’s texture and flow. A pressed tablet or hard candy calls for the crystalline powder. Both forms trace back to the same three-step process: starch extraction, enzymatic conversion to maltose, and catalytic hydrogenation into the final sugar alcohol.