Fructose is a structural isomer of glucose, meaning it has the same chemical ormula but a completely different three-dimensional structure. The main difference is that fructose is a ketone in its linear form while glucose is an aldehyde. Through an intramolecular addition reaction with the C-5 OH group, glucose forms a six-membered ring while fructose forms a five-membered ring. Upon consumption, fructose is absorbed and converted into glucose by the liver in the same manner as lactose. Sources of fructose include fruit, honey and high-fructose corn syrup.
Fructose, also levulose or fruit sugar, monosaccharide with the formula C6H12O6 that occurs with glucose in sweet fruits and fruit juices. It is formed along with glucose in the splitting of sucrose and is produced in the hydrolysis of various carbohydrates, but it is best prepared by treating inulin with dilute acid. Fructose is crystallized with difficulty; the crystals melt in the range from 102° to 104° C (216° to 219° F). It is laevorotatory; that is, solutions of fructose rotate the plane of polarized light to the left. Fructose is fermented by yeast to yield ethyl alcohol and carbon dioxide.
Fructose, or levulose, is the form of sugar found in fruit and honey. It is a laevorotatory monosaccharide with the same empirical formula as glucose but with a different structure. Although fructose is a hexose (6 carbon atoms), it generally exists as a 5-membered hemiketal ring (a furanose). All fruit naturally contains a certain amount of fructose (often together with glucose), and it can be extracted and concentrated to make an alternative sugar.
Fructose is often used in food products designed for people with diabetes mellitus or who have problems with hypoglycaemia, because it is metabolised more slowly than cane sugar (sucrose) and is sweeter, so it has a smaller effect on blood-sugar levels. However, some people can react badly to fructose so it is not an option for those who need to restrict sucrose intake.
Fructose is more commonly found together with glucose and sucrose in honey and fruit juices. Fructose, along with glucose are the monosaccharides found in disaccharide, sucrose. Fructose is classified as a monosaccharide, the most important ketose sugar, a hexose, and is a reducing sugar. An older common name for fructose is levulose, after its levorotatory property of rotating plane polarized light to the left (in contrast to glucose which is dextrorotatory). Bees gather nectar from flowers which contains sucrose. They then use an enzyme to hydrolyze or break apart the sucrose into its component parts of glucose and fructose.
Synonyms: fructose, frutabs, laevoral, laevosan, levugen, arabino-hexulose, D-(-)-fructose, D-(-)-levulose, fruit sugar, furucton, krystar, nevulose
Molecular formula: C6H12O6
CAS No: 57-48-7
EC No: 200-333-3