A furanose is a collective term for carbohydrates that have a chemical structure that includes a five-membered ring system consisting of four carbon atoms and one oxygen atom. The name derives from its similarity to the oxygen heterocycle furan, but the furanose ring does not have double bonds; the furanose ring is a cyclic hemiketal of a ketohexose. A furanose ring structure consists of four carbon and one oxygen atom with the anomeric carbon to the right of the oxygen; the highest numbered chiral carbon determines whether or not the structure has a d-configuration or L-configuration. In an l-configuration furanose, the substituent on the highest numbered chiral carbon is pointed downwards out of the plane, in a D-configuration furanose, the highest numbered chiral carbon is facing upwards; the furanose ring will have either alpha or beta configuration, depending on which direction the anomeric hydroxy group is pointing. In a d-configuration furanose, alpha configuration has the hydroxy pointing down, beta has the hydroxy pointing up.
It is the opposite in an l-configuration furanose. The anomeric carbon undergoes mutarotation in solution, the result is an equilibrium mixture of alpha-beta configurations. Pyranose
A carbohydrate is a biomolecule consisting of carbon and oxygen atoms with a hydrogen–oxygen atom ratio of 2:1 and thus with the empirical formula Cmn. This formula holds true for monosaccharides; some exceptions exist. The carbohydrates are technically hydrates of carbon; the term is most common in biochemistry, where it is a synonym of saccharide, a group that includes sugars and cellulose. The saccharides are divided into four chemical groups: monosaccharides, disaccharides and polysaccharides. Monosaccharides and disaccharides, the smallest carbohydrates, are referred to as sugars; the word saccharide comes from the Greek word σάκχαρον, meaning "sugar". While the scientific nomenclature of carbohydrates is complex, the names of the monosaccharides and disaccharides often end in the suffix -ose, as in the monosaccharides fructose and glucose and the disaccharides sucrose and lactose. Carbohydrates perform numerous roles in living organisms. Polysaccharides serve as structural components; the 5-carbon monosaccharide ribose is an important component of coenzymes and the backbone of the genetic molecule known as RNA.
The related deoxyribose is a component of DNA. Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, preventing pathogenesis, blood clotting, development, they are found in a wide variety of processed foods. Starch is a polysaccharide, it is abundant in cereals and processed food based on cereal flour, such as bread, pizza or pasta. Sugars appear in human diet as table sugar, lactose and fructose, both of which occur in honey, many fruits, some vegetables. Table sugar, milk, or honey are added to drinks and many prepared foods such as jam and cakes. Cellulose, a polysaccharide found in the cell walls of all plants, is one of the main components of insoluble dietary fiber. Although it is not digestible, insoluble dietary fiber helps to maintain a healthy digestive system by easing defecation. Other polysaccharides contained in dietary fiber include resistant starch and inulin, which feed some bacteria in the microbiota of the large intestine, are metabolized by these bacteria to yield short-chain fatty acids.
In scientific literature, the term "carbohydrate" has many synonyms, like "sugar", "saccharide", "ose", "glucide", "hydrate of carbon" or "polyhydroxy compounds with aldehyde or ketone". Some of these terms, specially "carbohydrate" and "sugar", are used with other meanings. In food science and in many informal contexts, the term "carbohydrate" means any food, rich in the complex carbohydrate starch or simple carbohydrates, such as sugar. In lists of nutritional information, such as the USDA National Nutrient Database, the term "carbohydrate" is used for everything other than water, fat and ethanol; this includes chemical compounds such as acetic or lactic acid, which are not considered carbohydrates. It includes dietary fiber, a carbohydrate but which does not contribute much in the way of food energy though it is included in the calculation of total food energy just as though it were a sugar. In the strict sense, "sugar" is applied for sweet, soluble carbohydrates, many of which are used in food.
The name "carbohydrate" was used in chemistry for any compound with the formula Cm n. Following this definition, some chemists considered formaldehyde to be the simplest carbohydrate, while others claimed that title for glycolaldehyde. Today, the term is understood in the biochemistry sense, which excludes compounds with only one or two carbons and includes many biological carbohydrates which deviate from this formula. For example, while the above representative formulas would seem to capture the known carbohydrates and abundant carbohydrates deviate from this. For example, carbohydrates display chemical groups such as: N-acetyl, carboxylic acid and deoxy modifications. Natural saccharides are built of simple carbohydrates called monosaccharides with general formula n where n is three or more. A typical monosaccharide has the structure H–x–y–H, that is, an aldehyde or ketone with many hydroxyl groups added one on each carbon atom, not part of the aldehyde or ketone functional group. Examples of monosaccharides are glucose and glyceraldehydes.
However, some biological substances called "monosaccharides" do not conform to this formula and there are many chemicals that do conform to this formula but are not considered to be monosaccharides. The open-chain form of a monosaccharide coexists with a closed ring form where the aldehyde/ketone carbonyl group carbon and hydroxyl group react forming a hemiacetal with a new C–O–C bridge. Monosaccharides can be linked togeth
Hydrolysis is a term used for both an electro-chemical process and a biological one. The hydrolysis of water is the separation of water molecules into hydrogen and oxygen atoms using electricity. Biological hydrolysis is the cleavage of biomolecules where a water molecule is consumed to effect the separation of a larger molecule into component parts; when a carbohydrate is broken into its component sugar molecules by hydrolysis, this is termed saccharification. Hydrolysis or saccharification is a step in the degradation of a substance. Hydrolysis can be the reverse of a condensation reaction in which two molecules join together into a larger one and eject a water molecule, thus hydrolysis adds water to break down, whereas condensation builds up by removing water and any other solvents. Some hydration reactions are hydrolysis. Hydrolysis is a chemical process in which a molecule of water is added to a substance. Sometimes this addition causes both water molecule to split into two parts. In such reactions, one fragment of the target molecule gains a hydrogen ion.
It breaks a chemical bond in the compound. A common kind of hydrolysis occurs when a salt of weak base is dissolved in water. Water spontaneously ionizes into hydroxide anions and hydronium cations; the salt dissociates into its constituent anions and cations. For example, sodium acetate dissociates in water into acetate ions. Sodium ions react little with the hydroxide ions whereas the acetate ions combine with hydronium ions to produce acetic acid. In this case the net result is a relative excess of hydroxide ions. Strong acids undergo hydrolysis. For example, dissolving sulfuric acid in water is accompanied by hydrolysis to give hydronium and bisulfate, the sulfuric acid's conjugate base. For a more technical discussion of what occurs during such a hydrolysis, see Brønsted–Lowry acid–base theory. Acid–base-catalysed hydrolyses are common, their hydrolysis occurs when the nucleophile attacks the carbon of the carbonyl group of the ester or amide. In an aqueous base, hydroxyl ions are better nucleophiles than polar molecules such as water.
In acids, the carbonyl group becomes protonated, this leads to a much easier nucleophilic attack. The products for both hydrolyses are compounds with carboxylic acid groups; the oldest commercially practiced example of ester hydrolysis is saponification. It is the hydrolysis of a triglyceride with an aqueous base such as sodium hydroxide. During the process, glycerol is formed, the fatty acids react with the base, converting them to salts; these salts are called soaps used in households. In addition, in living systems, most biochemical reactions take place during the catalysis of enzymes; the catalytic action of enzymes allows the hydrolysis of proteins, fats and carbohydrates. As an example, one may consider proteases, they catalyse the hydrolysis of interior peptide bonds in peptide chains, as opposed to exopeptidases. However, proteases do not catalyse the hydrolysis of all kinds of proteins, their action is stereo-selective: Only proteins with a certain tertiary structure are targeted as some kind of orienting force is needed to place the amide group in the proper position for catalysis.
The necessary contacts between an enzyme and its substrates are created because the enzyme folds in such a way as to form a crevice into which the substrate fits. Therefore, proteins that do not fit into the crevice will not undergo hydrolysis; this specificity preserves the integrity of other proteins such as hormones, therefore the biological system continues to function normally. Upon hydrolysis, an amide converts into an amine or ammonia. One of the two oxygen groups on the carboxylic acid are derived from a water molecule and the amine gains the hydrogen ion; the hydrolysis of peptides gives amino acids. Many polyamide polymers such as nylon 6,6 hydrolyse in the presence of strong acids; the process leads to depolymerization. For this reason nylon products fail by fracturing. Polyesters are susceptible to similar polymer degradation reactions; the problem is known as environmental stress cracking. Hydrolysis is related to energy storage. All living cells require a continual supply of energy for two main purposes: the biosynthesis of micro and macromolecules, the active transport of ions and molecules across cell membranes.
The energy derived from the oxidation of nutrients is not used directly but, by means of a complex and long sequence of reactions, it is channelled into a special energy-storage molecule, adenosine triphosphate. The ATP molecule contains pyrophosphate linkages. ATP can undergo hydrolysis in two ways: the removal of terminal phosphate to form adenosine diphosphate and inorganic phosphate, or the removal of a terminal diphosphate to yield adenosine monophosphate and pyrophosphate; the latter undergoes further cleavage in
Glycolaldehyde is the organic compound with the formula HOCH2-CHO. It is the smallest possible molecule that contains both a hydroxyl group, it is a reactive molecule that occurs both in the biosphere and in the interstellar medium. It is supplied as a white solid. Although it conforms to the general formula for carbohydrates, Cnn, it is not considered to be a saccharide. Glycolaldehyde exists; as a solid and molten liquid, it exists as a dimer. In aqueous solution, it exists as a mixture of at least four species, which interconvert, it is the only possible diose, a 2-carbon monosaccharide, although a diose is not a saccharide. While not a true sugar, it is the simplest sugar-related molecule, it is reported to taste sweet. Glycolaldehyde is the second most abundant compound formed. Glycolaldehyde can be synthesized by the oxidation of ethylene glycol using hydrogen peroxide in the presence of Iron sulphate, it can form by action of ketolase on fructose 1,6-bisphosphate in an alternate glycolysis pathway.
This compound is transferred by thiamine pyrophosphate during the pentose phosphate shunt. In purine catabolism, xanthine is first converted to urate; this is converted to 5-hydroxyisourate, which decarboxylates to allantoic acid. After hydrolyzing one urea, this leaves glycolureate. After hydrolyzing the second urea, glycolaldehyde is left. Two glycolaldehydes condense to form erythrose 4-phosphate, which goes to the pentose phosphate shunt again. Glycolaldehyde is an intermediate in the formose reaction. In the formose reaction, two formaldehyde molecules condense to make glycolaldehyde. Glycolaldehyde is converted to glyceraldehyde; the presence of this glycolaldehyde in this reaction demonstrates how it might play an important role in the formation of the chemical building blocks of life. Nucleotides, for example, rely on the formose reaction to attain its sugar unit. Nucleotides are essential for life, because they compose the genetic information and coding for life, it is invoked in theories of abiogenesis.
In the laboratory, it can be converted to amino acids and short dipeptides may have facilitated the formation of complex sugars. For example, L-valyl-L-valine was used as a catalyst to form tetroses from glycolaldehyde. Theoretical calculations have additionally shown the feasibility of dipeptide-catalyzed synthesis of pentoses; this formation showed stereospecific, catalytic synthesis of D-ribose, the only occurring enantiomer of ribose. Since the detection of this organic compound, many theories have been developed related various chemical routes to explain its formation in stellar systems, it was found that UV-irradiation of methanol ices containing CO yielded organic compounds such as glycolaldehyde and methyl formate, the more abundant isomer of glycolaldehyde. The abundances of the products disagree with the observed values found in IRAS 16293-2422, but this can be accounted for by temperature changes. Ethylene Glycol and glycolaldehyde require temperatures above 30 K; the general consensus among the astrochemistry research community is in favor of the grain surface reaction hypothesis.
However, some scientists believe the reaction occurs within colder parts of the core. The dense core will not allow for irradiation; this change will alter the reaction forming glycolaldehyde. The different conditions studied indicate how problematic it could be to study chemical systems that are light-years away; the conditions for the formation of glycolaldehyde are still unclear. At this time, the most consistent formation reactions seems to be on the surface of ice in cosmic dust. Glycolaldehyde has been identified in gas and dust near the center of the Milky Way galaxy, in a star-forming region 26000 light-years from Earth, around a protostellar binary star, IRAS 16293-2422, 400 light years from Earth. Observation of in-falling glycolaldehyde spectra 60 AU from IRAS 16293-2422 suggests that complex organic molecules may form in stellar systems prior to the formation of planets arriving on young planets early in their formation; the interior region of a dust cloud is known to be cold. With temperatures as cold as 4 Kelvin the gases within the cloud will freeze and fasten themselves to the dust, which provides the reaction conditions conducive for the formation of complex molecules such as glycolaldehyde.
When a star has formed from the dust cloud, the temperature within the core will increase. This will cause the molecules on the dust to be released; the molecule will emit radio waves that can be analyzed. The Atacama Large Millimeter/submilliter Array first detected glycolaldehyde. ALMA consists of 66 antennas. On October 23, 2015, researchers at the Paris Observatory announced the discovery of glycolaldehyde and ethyl alcohol on Comet Lovejoy, the first such identification of these substances in a comet. "Cold Sugar in Space Provides Clue to the Molecular Origin of Life". National Radio Astronomy Observatory. September 20, 2004. Retrieved December 20, 2006
The soybean, or soya bean, is a species of legume native to East Asia grown for its edible bean, which has numerous uses. Fat-free soybean meal is a significant and cheap source of protein for animal feeds and many packaged meals. For example, soybean products, such as textured vegetable protein, are ingredients in many meat and dairy substitutes; the beans contain significant amounts of dietary minerals and B vitamins. Soy vegetable oil, used in food and industrial applications, is another product of processing the soybean crop. Traditional unfermented food uses of soybeans include soy milk, from which tofu and tofu skin are made. Fermented soy foods include soy sauce, fermented bean paste and tempeh. "Soy" originated as a corruption of the Japanese names for soy sauce. The etymology of the genus, comes from Linnaeus; when naming the genus, Linnaeus observed that one of the species within the species had a sweet root. Based on the sweetness, the Greek word for sweet, glykós, was Latinized; the genus name is not related to the amino acid glycine.
The genus Glycine Willd. is divided into two subgenera and Soja. The subgenus Soja F. J. Herm. Includes the cultivated soybean, Glycine max Merr. and the wild soybean, Glycine soja Sieb. & Zucc. Both species are annuals. Glycine soja is the wild ancestor of Glycine max, grows wild in China, Japan and Russia; the subgenus Glycine consists of at least 25 wild perennial species: for example, Glycine canescens F. J. Herm. and G. tomentella Hayata, both found in Australia and Papua New Guinea. Perennial soybean is now a widespread pasture crop in the tropics. Like some other crops of long domestication, the relationship of the modern soybean to wild-growing species can no longer be traced with any degree of certainty, it is a cultural variety with a large number of cultivars. Like most plants, soybeans grow in distinct morphological stages as they develop from seeds into mature plants; the first stage of growth is germination, a method which first becomes apparent as a seed's radicle emerges. This is the first stage of root growth and occurs within the first 48 hours under ideal growing conditions.
The first photosynthetic structures, the cotyledons, develop from the hypocotyl, the first plant structure to emerge from the soil. These cotyledons both act as leaves and as a source of nutrients for the immature plant, providing the seedling nutrition for its first 7 to 10 days; the first true leaves develop as a pair of single blades. Subsequent to this first pair, mature nodes form compound leaves with three blades. Mature trifoliolate leaves, having three to four leaflets per leaf, are between 6–15 cm long and 2–7 cm broad. Under ideal conditions, stem growth continues. Before flowering, roots can grow 1.9 cm per day. If rhizobia are present, root nodulation begins by the time. Nodulation continues for 8 weeks before the symbiotic infection process stabilizes; the final characteristics of a soybean plant are variable, with factors such as genetics, soil quality, climate affecting its form. Flowering is triggered by day length beginning once days become shorter than 12.8 hours. This trait is variable however, with different varieties reacting differently to changing day length.
Soybeans form inconspicuous, self-fertile flowers which are borne in the axil of the leaf and are white, pink or purple. Depending of the soybean variety, node growth may cease. Strains that continue nodal development after flowering are termed "indeterminates" and are best suited to climates with longer growing seasons. Soybeans drop their leaves before the seeds are mature; the fruit is a hairy pod that grows in clusters of three to five, each pod is 3–8 cm long and contains two to four seeds 5–11 mm in diameter. Soybean seeds come in a wide variety sizes and hull colors such as black, brown and green. Variegated and bicolored seed coats are common; the hull of the mature bean is hard, water-resistant, protects the cotyledon and hypocotyl from damage. If the seed coat is cracked, the seed will not germinate; the scar, visible on the seed coat, is called the hilum and at one end of the hilum is the micropyle, or small opening in the seed coat which can allow the absorption of water for sprouting.
Some seeds such as soybeans containing high levels of protein can undergo desiccation, yet survive and revive after water absorption. A. Carl Leopold began studying this capability at the Boyce Thompson Institute for Plant Research at Cornell University in the mid-1980s, he found soybeans and corn to have a range of soluble carbohydrates protecting the seed's cell viability. Patents were awarded to him in the early 1990s on techniques for protecting biological membranes and proteins in the dry state. Like many legumes, soybeans can fix atmospheric nitrogen, thanks to symbiotic bacteria from the Rhizobia group. Together and soybean oil content account for 56% of dry soybeans by weight; the remainder consists of 9 % water and 5 % ash. Soybeans comprise 8% seed coat or hull, 90% cotyledons and 2% hypocotyl axis or germ. 100 grams of raw soybeans supply 446 calories and are 9% water, 30% carbohydrates, 20% total fat and 36% p
Fructose, or fruit sugar, is a simple ketonic monosaccharide found in many plants, where it is bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorbed directly into blood during digestion. Fructose was discovered by French chemist Augustin-Pierre Dubrunfaut in 1847; the name "fructose" was coined in 1857 by the English chemist William Allen Miller. Pure, dry fructose is a sweet, odorless, crystalline solid, is the most water-soluble of all the sugars. Fructose is found in honey and vine fruits, flowers and most root vegetables. Commercially, fructose is derived from sugar cane, sugar beets, maize. Crystalline fructose is the monosaccharide, ground, of high purity. High-fructose corn syrup is a mixture of fructose as monosaccharides. Sucrose is a compound with one molecule of glucose covalently linked to one molecule of fructose. All forms of fructose, including fruits and juices, are added to foods and drinks for palatability and taste enhancement, for browning of some foods, such as baked goods.
About 240,000 tonnes of crystalline fructose are produced annually. Excessive consumption of fructose may contribute to insulin resistance, elevated LDL cholesterol and triglycerides, leading to metabolic syndrome, type 2 diabetes and cardiovascular disease; the European Food Safety Authority stated that fructose is preferable over sucrose and glucose in sugar-sweetened foods and beverages because of its lower effect on postprandial blood sugar levels, noted that "high intakes of fructose may lead to metabolic complications such as dyslipidaemia, insulin resistance, increased visceral adiposity". Further, the UK’s Scientific Advisory Committee on Nutrition in 2015 disputed the claims of fructose causing metabolic disorders, stating that "there is insufficient evidence to demonstrate that fructose intake leads to adverse health outcomes independent of any effects related to its presence as a component of total and free sugars." The word "fructose" was coined in 1857 from the Latin for fructus and the generic chemical suffix for sugars, -ose.
It is called fruit sugar and levulose. Fructose is a 6-carbon polyhydroxyketone. Crystalline fructose adopts a cyclic six-membered structure owing to the stability of its hemiketal and internal hydrogen-bonding; this form is formally called D-fructopyranose. In water solution, fructose exists as an equilibrium mixture of 70% fructopyranose and about 22% fructofuranose, as well as small amounts of three other forms, including the acyclic structure. Fructose may be anaerobically fermented by yeast or bacteria. Yeast enzymes convert sugar to carbon dioxide; the carbon dioxide released during fermentation will remain dissolved in water, where it will reach equilibrium with carbonic acid, unless the fermentation chamber is left open to the air. The dissolved carbon dioxide and carbonic acid produce the carbonation in bottled fermented beverages. Fructose undergoes non-enzymatic browning, with amino acids; because fructose exists to a greater extent in the open-chain form than does glucose, the initial stages of the Maillard reaction occur more than with glucose.
Therefore, fructose has potential to contribute to changes in food palatability, as well as other nutritional effects, such as excessive browning and tenderness reduction during cake preparation, formation of mutagenic compounds. Fructose dehydrates to give hydroxymethylfurfural; this process, in the future, may become part of a low-cost, carbon-neutral system to produce replacements for petrol and diesel from plants. The primary reason that fructose is used commercially in foods and beverages, besides its low cost, is its high relative sweetness, it is the sweetest of all occurring carbohydrates. The relative sweetness of fructose has been reported in the range of 1.2–1.8 times that of sucrose. However, it is the 6-membered ring form of fructose, sweeter. Warming fructose leads to formation of the 5-membered ring form. Therefore, the relative sweetness decreases with increasing temperature; however it has been observed that the absolute sweetness of fructose is identical at 5 °C as 50 °C and thus the relative sweetness to sucrose is not due to anomeric distribution but a decrease in the absolute sweetness of sucrose at lower temperatures.
The sweetness of fructose is perceived earlier than that of sucrose or glucose, the taste sensation reaches a peak and diminishes more than that of sucrose. Fructose can enhance other flavors in the system. Fructose exhibits a sweetness synergy effect; the relative sweetness of fructose blended with sucrose, aspartame, or saccharin is perceived to be greater than the sweetness calculated from individual components. Fructose has higher water solubility than other sugars, as well as other sugar alcohols. Fructose is, difficult to crystallize from an aqueous solution. Sugar mixes containing fructose, such as candies, are softer than those containing other sugars because of the greater solubility of fructose. Fructose is quicker to absorb moisture and slower to release it to the environment than sucrose, glucose, or other nutritive sweeteners. Fructose is an excellent humectant and retains moisture for a long period of time at low relative humidity. Therefore, fructose can contribute a more palatable texture, longer shelf life to the food products in which it is used.
Fructose has a greater effect on freezing point depression than disaccharides or oligosaccharides, which may prot
A triose is a monosaccharide, or simple sugar, containing three carbon atoms. There are only three possible trioses: L-Glyceraldehyde and D-Glyceraldehyde, the two enantiomers of glyceraldehyde, which are aldotrioses because the carbonyl group is at the end of the chain, dihydroxyacetone, the only ketotriose, symmetrical and therefore has no enantiomers. Trioses are important in cellular respiration. During glycolysis, fructose-1,6-bisphosphate is broken down into glyceraldehyde-3-phosphate and dihydroxyacetone phosphate. Lactic acid and pyruvic acid are derived from these molecules