What is fructo-oligosaccharides? Fructo-oligosaccharide(FOS) is an important type in oligosaccharides, also called as kestose oligosaccharide. It refers to kestose, nystose, 1F-fructofuranosylnystose and their mixtures that fructose residues of sucrose molecule, by β(2—1)glucosidic bond, connect with 1~3 fructosyls. It’s an excellent soluble dietary fiber. As a special health food, FOS has a significant effect in improving stomach and intestine’s function, lowing blood fat, regulating body balance and improving immunity. So it is widely used in health food, beverage, dairy products, candies, feed industry and medical, hairdressing industry. Its application prospect is very spacious.