Also known as Palatinit®
Isomalt is a polyol (sugar alcohol). It is produced from sucrose in two steps: enzymatic rearrangement of sucrose to isomaltulose, followed by hydrogenation. It is a mixture of two compounds, glucosyl-mannitol and glucosyl-sorbitol.
Isomalt has a clean sweet taste. It iis about 40% as sweet as sucrose, on a weight basis.
Isomalt is not efficiently absorbed by the body, and it is only partly metabolized. Its caloric value depends on several factors, as discussed in my essay "Polyols and Calories." In the USA, isomalt provides 2 calories per gram for labeling purposes. In the European Union, it is listed at 2.4 calories per gram.
Isomalt's physical properties are very similar to sucrose, making it useful in hard candies and many other products. It is less hygroscopic (less likely to pick up moisture from the air) than most polyols and sugars, so products made with isomalt may be less sticky and may have better shelf life. Isomalt has very good heat stability, so it can be used in making hard candies and baked goods.
Isomalt has had GRAS status in the United States since 1990. It has been in use in Europe since the early 1980s.
The Joint FAO/WHO Expert Committee on Food Additives has determined the "Laxative Threshold Value" (LTV) for a number of polyols, and lactitol has an LTV of 29 grams per meal.