Raffinose is a dextrorotatory trisaccharide, occurring in cotton seed and in the molasses of beet root, composed of d-galactose, d-glucose, and d-fructose and formed by transfer of d-galactose from UDP-d-galactose to sucrose; many seeds are rich in raffinose. Raffinose can be hydrolyzed to sucrose and galactose by the enzyme α-galactosidase (α-GAL). Humans do not possess the α-GAL enzyme in their small intestine to break down the trisaccharide. Thus bigger amounts of raffinose reach the large intestine, where bacteria of the gut flora perform the break down and produce gases. This may cause flatulence. Due to its indestigibility, raffinose is sometimes used in foods to reduce calories. Legume seeds (peas, beans, lentils) contain 5 to 15 % raffinose in their dry weight. During the production of beet sugar, major amounts of raffinose accumulate in the molasses, which can be used to produce some kinds of brown sugars. Technically, raffinose can be used as a antifreezing agent (freezing medical preparates, cryopreservation). Dietary raffinose has being shown to suppress serum immunoglobulin E response through suppression of Th2-type immune response against oral antigen in the lymphoid organs located in or near the intestine. 4.5% raffinose is an effective osmotic agent. Raffinose has being used experimentally as an osmotic agent for peritoneal dialysis. Raffinose is used in reproductive medicine. The addition of raffinose to media containing glucose improved motility of sperm stored at 3 degrees C for 6 h.