Kestose is a trisaccharide belonging to the class of fructooligosaccharides (FOS), consisting of one fructose molecule attached to a sucrose molecule. The most common form, 1-kestose, features a fructose unit linked to the glucose part of sucrose by a β-(2→1) glycosidic bond. Its molecular formula is C18H32O16, with a molecular weight of approximately 504.4 g/mol. Other variants include 6-kestose and neokestose, which differ in the position and linkage types of the fructose residues.
Kestose serves as a prebiotic compound, promoting the growth of beneficial gut bacteria such as bifidobacteria and lactobacilli. It is naturally found in many plants, including onions, asparagus, and chicory, playing a role in carbohydrate storage and plant metabolism. Due to its nondigestible nature in the human upper gastrointestinal tract, kestose reaches the colon where it is fermented by the microbiota, contributing to improved gut health and immune modulation.
Biochemical Synthesis and Function
Biochemically, kestose is synthesized by specific fructosyltransferase enzymes in plants, and its ability to form longer fructan chains classifies it as a building block for more complex fructooligosaccharides. Its functional properties have led to its application in food and nutrition industries as a dietary fiber and prebiotic ingredient.
In summary, kestose is a naturally occurring fructooligosaccharide trisaccharide that plays significant roles in plant carbohydrate metabolism and human gut health through its prebiotic effects.