Humectants are additives that bind water and control water activity (aw). They are believed to reduce water activity of a product due to the presence of hydrophilic group such as hydroxyl groups, which have affinity to form hydrogen bonds with molecules of water, thus decreasing the availability of free water.
Water activity reduction achieved by adding humectants to food enhances stability, maintains texture, and reduces microbial activity.
Salt and sugar are the oldest, most widely used humectants. Other commonly used humectants include sorbitol, glycerol and propylene glycol.
They can be added to the food system to develop more favorable conditions, without adversely affecting flavor and texture.
Propylene glycol is used to maintain moisture within a narrow range in certain food products, such as coconut and marshmallows, in certain medicines and cosmetics as well as in tobacco, and is a solvent for food colors and flavors.
Glycerol is used as a solvent for flavors and food colors. It is also used as a humectant, plasticizer, emollient, sweetener, and filler in low-fat food products such as cookies. Glycerol is a common energy yielding food and is widely distributed in food, both as a natural constituent and as a GRAS (generally recognized as safe) additive.
Sorbitol is widely present in nature, particularly as a constituent of many fruits and berries. Sorbitol syrup is used as an efficient humectant, and as a sequestering and emulsifying agent in confectionery and bakery products, as well as in mayonnaise, creams and sauces.
Humectants
