Maltose

8 Key excerpts on "Maltose"

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  Organic Chemistry

  • David R. Klein(Author)
  • 2016(Publication Date)
  • Wiley

    (Publisher)

  Identify both epimers. 24.7 Disaccharides Maltose Disaccharides are carbohydrates comprised of two monosaccharide units joined via a glycosidic linkage between the anomeric carbon of one monosaccharide and a hydroxyl group of the other monosaccharide. For example, consider the structure of Maltose (shown at left). Maltose is obtained from the hydrolysis of starch. It is comprised of two α-d-glucopyranose units joined between the anomeric carbon (C1) of one glucopyranose unit and the OH at C4 of the other glucopyranose unit. This type of linkage is called a 1→4 link. Two monosaccharides can link together in a variety of ways, but the 1→4 link is especially common. Maltose undergoes mutarotation, because one of the rings (bottom right) is a hemiacetal. As a result, the anomeric position of that ring is capable of opening and closing, allowing for equilibration between the two possible anomers. CH 2 OH O HO HO O OH CH 2 OH O HO OH OH CH 2 OH O HO HO O OH CH 2 OH O HO OH OH H 2 O These anomers are interchanged as a result of mutarotation, which occurs more rapidly in the pres- ence of catalytic acid or base. Maltose is also a reducing sugar because one of the rings is a hemiacetal and exists in equilibrium with the open-chain form. O H CH 2 OH O HO HO O OH CH 2 OH O HO OH OH CH 2 OH O HO HO O OH CH 2 OH OH HO OH In the presence of an oxidizing agent, the aldehyde group of the open-chain form is oxidized to give an aldonic acid. CH 2 OH O HO HO O OH CH 2 OH O HO OH OH 1 4 Maltose (a 1 4 α-glycoside) 24.7 Disaccharides 1129 STEP 1 Identify the anomeric position on each ring. STEP 2 Determine if the group at each anomeric position is a hydroxy group or alkoxy group. SKILLBUILDER LEARN the skill 24.5 DETERMINING WHETHER A DISACCHARIDE IS A REDUCING SUGAR Determine whether lactose is a reducing sugar: SOLUTION Begin by identifying the anomeric carbon on each ring. Remember the anomeric position of a ring is the position that is connected to two oxygen atoms.

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  Sweeteners

  Nutritional Aspects, Applications, and Production Technology

  • Theodoros Varzakas, Athanasios Labropoulos, Stylianos Anestis(Authors)
  • 2012(Publication Date)
  • CRC Press

    (Publisher)

  The solubility of lactose is less than that of most other sugars, which may present problems in a number of foods containing lactose (Izydorczyk 2005). Finally, like all reducing sugars, lactose can undergo Maillard (nonenzymatic browning) reaction, resulting in (off-) flavor compounds and brown poly-mer production (Fox 2009). Maltose : Maltose is a disaccharide formed from two units of glucose joined with an α -(1 → 4) glycosidic bond (Figure 2.18). It rotates the plane-polarized light to the right and has a specific optical rotation of [ ] α D ° 20 136 = + . Maltose is the major end product of the enzymatic degradation of 0 20 40 60 80 100 120 140 160 0 20 40 60 80 100 120 Solubility (g anhydrous lactose/100 g water) Temperature (°C) Usual range of supersaturation 93.5°C Initial solubility of β-lactose Initial solubility of α-lactose Final solubility at equilibrium Figure 2.17 Solubility of α - and β -lactose as a function of temperature. (Adapted from Fox, P. F. and McSweeney, P. L. H., Dairy Chemistry and Biochemistry , Chapman & Hall, London, 1998.) CH 2 OH CH 2 OH OH OH H H H H H H H O OH H H O O O H H OH OH Figure 2.18 Structure of Maltose. 25 CHEMISTRY AND FUNCTIONAL PROPERTIES OF CARBOHYDRATES AND SUGARS starch by maltases, and it has a characteristic flavor of malt. It is a readily yeast-fermentable sugar, reduces Fehling’s solution, is easily soluble in water and slightly soluble in ethanol, and presents mutarotation (deMan 1999). Cellobiose : Cellobiose is a reducing disaccharide formed from two units of glucose joined with a β -(1 → 4) glycosidic bond (Figure 2.19). It can be obtained by enzymatic or acid hydrolysis of cel-lulose. Cellobiose is differentiated from Maltose in the kind of glycosidic bond between the glucose units. It is enzymatically hydrolyzed by the enzyme emulsine (deMan 1999). 2.4.2 Trisaccharides and Tetrasaccharides The most important trisaccharide is raffinose that is composed of galactose, glucose, and fruc-tose (Figure 2.20).

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  Food Carbohydrates

  Chemistry, Physical Properties, and Applications

  • Steve W. Cui(Author)
  • 2005(Publication Date)
  • CRC Press

    (Publisher)

  Maltose, although it rarely occurs in plants, can be readily produced by hydrolysis of starch. Maltose is therefore present in malted grains and various food items containing starch hydrolysis products (e.g., corn syrup). α , α -Trehalose occurs in the spores of fungi and it is also produced by yeasts. IsoMaltose constitutes the branch point of amylopectin and glycogen. Cellobiose is a product of bacterial hydrolysis of cellulose by enzymes such as endo-cellu-lases and cellobiohydrolases. Laminaribiose is a repeating unit found in the polysaccharides, laminarin (brown algae), pachyman (fungi), and callose. Disaccharides can be divided into heterogeneous and homogeneous types, according to their monosaccharide composition, and into reducing or non-reducing disaccharides , depending whether they possess a free anomeric carbon. Homodisaccharides contain two identical monosaccharide units, whereas heterodisaccharides are composed of two different monomers. Reducing disaccharides, in contrast to nonreducing ones, contain a reactive hemiacetal center that can be easily modified chemically (e.g., via oxidation or reduction). The two most important naturally occurring heterodisaccharides are sucrose and lactose. Sucrose (commonly known as sugar or table sugar) occurs in all plants, but it is commercially obtained from sugar cane and sugar beets. It is composed of an α -D -glucopyranosyl unit and a β -D -fructofuranosyl unit linked reducing end to reducing end, thus it is a nonreducing sugar (Figure 1.22). Its chemical name is α -D -glucopyranosyl-β -D -fructofuranoside. Sucrose is the world’s main sweetening agent and about 10 8 tonnes are produced annually. Sucrose is common in many baked products, breakfast cereals, deserts, and beverages. Sucrose is hydrolyzed into D -glucose and FIGURE 1.18 A β -1 → 2 linked disaccharide.

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  Klein's Organic Chemistry

  • David R. Klein(Author)
  • 2020(Publication Date)
  • Wiley

    (Publisher)

  (a) CH 2 OH O HO HO O OH CH 2 OH O HO OH OH (b) O OH HO O OH OH O HO OCH 3 OH OH 24.7 Disaccharides 1121 Cellobiose Another example of a disaccharide is cellobiose, which is obtained from the hydrolysis of cellulose. It is comprised of two β-d-glucopyranose units joined by a 1→4 link. CH 2 OH O HO HO O OH CH 2 OH O HO OH OH 1 4 Cellobiose (a 1 4 β-glycoside) This compound is very similar in structure to Maltose, only it is comprised of β-d-glucopyranose units rather than α-d-glucopyranose units. Much like Maltose, cellobiose also exhibits mutarotation and is a reducing sugar, because the ring on the right is a hemiacetal and is therefore capable of opening and closing. APPLY the skill need more PRACTICE? (c) HOCH 2 O HO HO O OH CH 2 OH OH OH O OH Sucrose 24.40 Trehalose is a naturally occurring disaccharide found in bacteria, insects, and many plants. It protects cells from dry conditions because of its ability to retain water, thereby prevent- ing cellular damage from dehydration. This property of trehalose has also been exploited in the preparation of food and cosmetics. Trehalose is not a reducing sugar, it is hydrolyzed to yield two equivalents of D-glucose, and it does not have any β-glycoside linkages. Draw the structure of trehalose. Try Problem 24.73 Lactose Lactose, commonly called milk sugar, is a naturally occurring disaccharide found in milk. Unlike Maltose or cellobiose, lactose is comprised of two different monosaccharides—galactose and glucose. The two monosaccharide units are joined by a 1→4 link, between C1 of galactose and C4 of glucose. Like the other disaccharides we have seen so far, lactose also exhibits mutarotation and is a reducing sugar, because the ring on the bottom right is a hemiacetal and is therefore capable of opening and closing.

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  Dietary Sugars

  Chemistry, Analysis, Function and Effects

  • Victor R Preedy(Author)
  • 2012(Publication Date)
  • Royal Society of Chemistry

    (Publisher)

  Thus, such residues confer structural configurations and biochemical features that permit enhanced molecular interactions with Maltose such that its transport across the membrane proceeds in an energy-driven mode. Summary Points This chapter focuses on the metabolism and transport of the sugar Maltose. The molecular mechanisms for the metabolism of Maltose and transport across the membrane are thought to be evolutionarily conserved across many taxa. Maltose as a dietary source for man can be found largely in vegetables, fruits, and grains. The transport of Maltose across the cellular membrane involves both passive and active transport systems that are homologous between lower and higher organisms. The selection of Maltose as a substrate for transport can be induced by minor sequence alteration in homologous sugar transport systems. Key Facts of Maltose Chemistry and Biochemistry Maltose is a disaccharide sugar consisting of 2 glucose molecules attached by a glycosidic bond and represents an important metabolite for living organisms. Starch is a common storage form for Maltose. Many aspects of the metabolic and transport machinery for Maltose share a common evolutionary origin, ranging from bacteria to man. Maltose is liberated from starch using a variety of enzymes, including a -amylase, b -amylase, glucoamylase, and debranching enzymes. Passive transport systems for Maltose consist of LamB as a key model protein for study. Active transport systems of Maltose include both primary and secondary transport systems. Primary active transport systems for Maltose include MalFGK 2 E. A secondary active Maltose transport system is CscB. 110 Chapter 7 Maltose group translocation systems include the Maltose PTS. Mutations in a variety of other sugar transporters have resulted in the enhancement of Maltose transport. Definition of Words and Terms Active transport: movement of solutes, e.g.

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  Carbohydrate Chemistry

  Volume 27

  • R J Ferrier(Author)
  • 2007(Publication Date)
  • Royal Society of Chemistry

    (Publisher)

  ~ ~ 3 Tetrasaccharides Compounds of this set are classified according to whether they have linear or branched structures and then by the nature of the sugars at the reducing termini. 3.1 Linear Homotetrasaccharides.-Perbenzyl maltosyl and maltotriosyl fluorides have been coupled by a-( 1 +4) bonds to a partially protected trehalose derivative by use of trimethylsilyl triflate and, after deblocking, a tetra- and a penta-glucose linked a-(1-+4) but terminating with a non-reducing unit were obtained. 65 An ingenious way of making cellotetraose involves coupling methyl cellotrioside with lactose under the influence of cellulase and then cleaving the galactose residue by use of a galactosidase.66 A related approach to maltotetraose involved reaction of starch with deoxynojirimycin in the presence of a cyclodextrin glycosyl transferase. A set of 66 Carbohydrate Chemistry oligosaccharides ending in the 5-amino- 1,5-aminohexitol were thereby produced, and by amylase they were cleavable to give products which included high purity maltotetraose.67 A set of P- (1+4)-linked glucosamine oligosaccharides ranging from the tetramer to the decamer has been described; they are thus the oligomers of chitosan.

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  Textbook on Food Science and Human Nutrition

  • Sharma, Dipiti(Authors)
  • 2021(Publication Date)
  • Daya Publishing House

    (Publisher)

  It is composed of glucose and fructose molecule linked by alpha bond. Significant amount of sucrose are found only in plants such as sugar cane, sugar beets, honey and maple syrups. This can be purified to various degrees. For ex. Brown sugar, white sugar and powdered sugars are common forms of sucrose sold in grocery shop. In the presence of mild acids or the enzyme invertase, sucrose undergoes hydrolysis (Inversion). The hydrolysis product is known as Invert Sugar . 3. Lactose This is the primary sugar of milk and milk products and is a constituent of mammalian milk. It consists of glucose joined to galactose with a beta bond. Many people are unable to digest large amounts of lactose, which can cause intestinal gas, bloating, cramping, and discomfort as the unabsorbed lactose is metabolized into acids and gases by bacteria in the large intestine. This is called as Lactose Intolerance. Lactose Intolerance Lactose intolerance refers to the inability to digest lactose results from a reduction in activity of the lactase enzyme. This enzyme is embedded within the surface of intestinal cells, splits lactose into glucose and galactose. These This ebook is exclusively for this university only. Cannot be resold/distributed. monosaccharides are absorbed from the small intestine into the bloodstreams, but lactose is not. When lactase activity is low, lactose travel unaltered into the large intestine, where resident bacteria metabolizes it into acids and gases causing intestinal gas, bloating, cramping and discomfort. Persons suffering from lactose intolerance can eat hard cheese and regular yoghurt. 4. Raffinose This sugar is formed by the addition of one galactose residue to sucrose molecules. So it consists of 3 monosacchaides (galactose-glucose-fructose). This sugar is indigestible by the humans. 5. Stachyose This sugar is formed by the addition of two galactose residue to sucrose molecules. So, it consist of 4 monosaccharides (galactose-galactose-glucose-fructose).

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  Biochemistry

  An Integrative Approach

  • John T. Tansey(Author)
  • 2019(Publication Date)
  • Wiley

    (Publisher)

  Plants synthesize sucrose as a way to temporarily store energy and to attract organisms to help pollinate a plant or disperse its seeds. The taste of sucrose is characteristically sweet, and it is used as the basis of comparison for all other sweeteners. Table sugar is crystalized sucrose often obtained from sugar cane or sugar beets. Sucrose can also be found in honey and maple syrup. The United States Department of Agriculture estimates that, by the mid-2000s, Americans were consuming close to 90 pounds of sugar per year as either sucrose or high fructose corn syrup. The chemistry and controversy of high fructose corn syrup is discussed in Societal and Ethical Biochemistry: The ongoing debate over high fructose corn syrup. Maltose Maltose (malt sugar) is a dimer of glucose molecules connected in an α-1,4 linkage (α-D-Glucopyranosyl-(1→4)-β-D-Glucopyranoside). Maltose is the major breakdown product formed when plants catabolize starch. When hearing the term “malt,” most people think of malted milk balls or malted milk; however, the molecule plays a central role in the brewing industry. Grains such as barley store energy as starch (polymers of glucose). When barley grains germinate, they mobilize the energy stored in starch as Maltose. An early step in beer pro- duction is malting of grain, in which the grains are kept damp and warm and are allowed to germinate. During the malting process, enzymes cleave Maltose, a dimer of glucose, from starch polymers. Following malting, the grains are roasted, and the soluble Maltose is then removed from the grain by steeping in warm water. This is the actual brewing step. These sol- uble carbohydrates provide the fuel source for yeast in the subsequent steps in beer production. During Prohibition in the 1920s and early 1930s, when the sale, manufacture, and transport of alcohol was banned in the United States, brewers stayed in business by producing malt for candy, cereal, and as a milk additive.

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