by Austin

Quick Reference Facts

Compound Name--------------------------------------------------------- Fructose

IUPAC Name ------- (3S,4R,5R)-1,3,4,5,6-pentahydroxyhexan-2-one

Other Names --------------------------------------------- Levulose, Fruit sugar

Chemical Formula ----------------------------------------------------- C6H12O6

Molar Mass ---------------------------------------------------------- 180.16 g/mol

Density --------------------------------------------------------------- No data found

Melting Point --------------------------------------------------------- 103-105° C

Boiling Point ------------------------------------------------------ No data found


Basic Information

Fructose is a white, odorless solid. It is a simple monosaccharide and can be found in many foods and parts of plants. It is also classified as the most important ketose sugar, a reducing sugar, and a hexose. Levulose, (another name of fructose), has the ability to dissolve in water. The name levulose comes from the fact that it has the levorotatory property of rotating plane polarized light counterclockwise. Fructose is a very sweet carbohydrate. It is one of the three most important blood sugars. Berries, melons, honey, tree fruits, and some root vegetables contain amounts of the fructose derivative, sucrose. Fructose, however, is approximately two times sweeter than sucrose. Pure fructose has a taste that is similar to sugarcane.

Fructose is a 6-carbon polyhydroxyketone. Fructose and glucose both have the chemical formula C6H12O6. However, fructose differs in structure from glucose; thus, why it is considered an isomerof glucose. Fructose usually adopts acyclic structures. This property allows the stability of its hemiketal. D-fructofuranose, as it was formally called, is a 5-member ring. When a hydroxyl group (OH) on the sixth carbon attaches to the carbonyl (C=O) carbon, a six-membered ring is formed, which is called D-Fructopyranose. Fructose is at an equilibrium mixture of 70% fructopyranose and 30% fructanose when in solution.

Isomers of Fructose

--------- Alpha-D-Fructose ----------------- Beta-D-Fructose ---------------------- Alpha-L-Fructose -------------------- Beta-L-Fructose

Found and Obtained

2933735054_549a20bf3a.jpgFructose can primarily be found in fruits, vegetables, and honey. It may exist in food as either a free monosaccharide or bonded to glucose as sucrose. Although the simple sugars glucose, fructose, and sucrose can be found in basically any food, the level of sugar present varies by food type. Examples of foods and commercial sweeteners that contain considerable amounts of fructose include: apples, apricots, bananas, grapes, peaches, pears, red beets, carrots, sweet corn, sweet red peppers, sweet onions, sweet potatoes, yams, sugar canes, sugar beets, granulated sugar, brown sugar, honey, maple syurp, molasses, and high-fructose corn syrup.

Fructose can best be obtained in a purified form by recovering plant parts that contain the fructose polymer. An example of such preparation is that of the hydrolysisof inulin: mix the plant parts with an aqueous solution of the fructose polymer hydrolyzing enzyme, inulase, and then recover the remaining solid plant parts and fructose crystals. Inulin is a polysaccharide that can be found in the Jerusalem artichoke and dahlia bulbs.

History of the Sugars

2271862634_20de5c69ac.jpgSugar has been around since before the birth of Christ. Even as early as 500 B.C., India was said to have sugarcane. The Arab invasion into India a thousand years later allowed for the spreading of sugarcane to the rest of the world. As the Arabs conquered Europe, they brough the sugarcane with them and introduced the discovery to North Africa and Spain. Christopher Columbus brought sugar to the Americas at a time when sugar was processed by boiling the cane juice and harvesting the remnant crystals.

Emil Fischer, a German chemist, began to study the sugars in 1884 and transformed the knowledge of the compounds. By passage to a common osazone, Fischer defined the relation between fructose, glucose, and mannose. In 1890, between gluconic and mannonic acids, he created the isomery of the sugars and also the stereochemical configuration of all known sugars. His synthesis of glucose, fructose, and mannose, starting from glycerol, is considered his greatest success.

Explanation of Structure

Type of Bonding
Fructose is comprised of carbon, hydrogen, and oxygen atoms.
These are all non-metals; thus, covalent bonding is within the fructose compound.
There is a carbonyl (C=O) group attached to the compound.

Percentage Composition by Number of Atoms
Carbon - 6/24 = 25%
Hydrogen - 12/24 = 50%
Oxygen - 6/24 = 25%

Percentage Composition by Mass of Atoms
Carbon - 6 mol C * (12.01 g / mol C) = 72.06 g / 180.16 g = 40%
Hydrogen - 12 mol H * (1.01 g / mol H) = 12.12 g / 180.16 g = 7%
Oxygen - 6 mol O * (16.00 g / mol O) = 96.00 g / 180.16 g = 53%

Chemical Properties and Reaction Tendencies

FermentationFructose can be feremented anaerobically by yeast or bacteria. The enzymes in yeast can convert sugar to ethanol and carbon dioxide. The carbon dioxide will remain dissolved in water, reach equilibrium, and react with carbonic acid to produce carbonation.

DehydrationFructose dehydrates to produce hydroxymethylfurfural, or HMF. Because glucose can isomerize into fructose allows the dehydration property.

Maillard Reaction
The Maillard Reaction is non-enzymatic browning with amino acids. The initial stages of the reaction occur more rapidly than with glucose because fructose exists to a great extent in the open-chain form. Because of its reaction's rapidity, fructose may contribute to food palatability and nutritional effects.


A-bee-collects-nectar-fro-001.jpgFructose is recommended to be consumed by those diagnosed with diabetes mellitus or hypoglycemia, being that fructose has an extremely low Glycemic Index (GI) relatvie to sucrose. It is used therapeutically as a nutrient replenisher and as a fluid. When bonded with glucose, bees gather nectar from flowers that contain the sucrose. They break apart collected sucrose into its components of fructose and glucose.

Fructose is used commercially in beverages, food products, and syrup because it is inexpensive and very sweet. Fructose also has the ability to enhance other flavors in the same system as well. The blended sweetness of fructose with sucrose, saccharin, or aspartame is greater than the sweetness from the individual components. Because fructose is a fantastic humectant and retains moisture for long periods of time, it can be used to improve quality, texture, and longer shelf stability for food products.

Health Effects and Dangers

DigestionFructose is absorbed by the GLUT-5 transporter, which is a fructose only transporter, but deficiencies of the GLUT-5 may occur when excess of fructose is carried into the lower intestine. This can provide nutrients for the gut flora, which are gas producers, and may cause water retention. These effects can cause loose stools, diarrhea, bloating, and excessive flatulence.
GoutOver-consumption of fructose may lead to gout, which is a diseases of elevated levels of uric acid in the bloodstream. Gout's causes have risen within the last couple of years. It is suspected that fructose in carbonated beverages and sweetened drinks is a cause for gout.

Liver Disease
Fructose may be better for diabetics than sugar, but all fructose must be almost entirely metabolized in the liver. A diet of fructose instead of glucose can result in lower levels of leptin and insulin. However, higher gherin levels may be reached after a meal. Eating large amounts of fructose may cause weight gain because leptin and insulin decrease appetite, while gherin increases appetite. Excess consumption can also suppress the feeling of fullness. It is believed that high fructose consumption can cause non-alcoholic fatty liver disease.

Metabolic SyndromesLarge consumptions of fructose may result in insulin resistance, elevated LSD cholesterol, triglycerides, and obesity, which can all cause metabolic syndrome. The chemical reaction of monosaccharides, or simple sugars to protein, referred to as glycation, is considered a factor of damage to diabetes patients.

High-Fructose Corn Syrup

High-fructose corn syrup (HFCS) and crystalline fructose are often confused as the same product. However, HFCS is considered to be comprised of practically equal amounts of fructose and glucose, while crystalline fructose is a moosaccharide. HFCS 42 is 42% fructose and 58% glucose. It is used in foods, particularly baked goods. HFSC 55, which is 55% fructose, is mainly used in soft drinks. 90% fructose, HFSC 90, is used to blend with HFCS 42 and 55, but is also used for small quantities.

Critics of HFCS have stated that it is more damaging to health than sucrose (table sugar), while others have concluded that HFCS is influential to over-consumption because of its inexpensive price. A study on soft drinks revealed that beverages sweetened with HFSC can be about 10 times richer in harmful carbonyl compounds than diet soft drinks. There is believed to be a link between obesity and excess fructose consumption, especially from these soft drinks. In fact, the average American consumes approximately 70 lb of HFCS yearly. Another study showed that some high-fructose corn syrup contained amounts of mercury, which appeared to come from hydrochloric acid and caustic soda. Nine out of twenty soda samples examined contained detectable amounts of mercury.

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