Lactose - wikipedia Lactose Lactose ( milk sugar ) Names IUPAC name β - D - galactopyranosyl - ( 1 → 4 ) - D - glucose Other names Milk sugar 4 - O - β - D - galactopyranosyl - D - glucose Identifiers CAS Number 63 - 42 - 3 3D model ( JSmol ) Interactive image ChEBI CHEBI : 36218 ChemSpider 5904 ECHA InfoCard 100.000. 509 EC Number 200 - 559 - 2 PubChem CID 6134 UNII 3SY5LH9PMK InChI InChI = 1S / C12H22O11 / c13 - 1 - 3 - 5 ( 15 ) 6 ( 16 ) 9 ( 19 ) 12 ( 22 - 3 ) 23 - 10 - 4 ( 2 - 14 ) 21 - 11 ( 20 ) 8 ( 18 ) 7 ( 10 ) 17 / h3 - 20H, 1 - 2H2 / t3 -, 4 -, 5 +, 6 +, 7 -, 8 -, 9 -, 10 -, 11 -, 12 + / m1 / s1 Key : GUBGYTABKSRVRQ - DCSYEGIMSA - N InChI = 1 / C12H22O11 / c13 - 1 - 3 - 5 ( 15 ) 6 ( 16 ) 9 ( 19 ) 12 ( 22 - 3 ) 23 - 10 - 4 ( 2 - 14 ) 21 - 11 ( 20 ) 8 ( 18 ) 7 ( 10 ) 17 / h3 - 20H, 1 - 2H2 / t3 -, 4 -, 5 +, 6 +, 7 -, 8 -, 9 -, 10 -, 11 -, 12 + / m1 / s1 Key : GUBGYTABKSRVRQ - DCSYEGIMBP SMILES C ( ( C @ @ H ) 1 ( C @ @ H ) ( ( C @ @ H ) ( ( C@H ) ( ( C @ @ H ) ( O1 ) O ( C @ @ H ) 2 ( C@H ) ( O ( C@H ) ( ( C @ @ H ) ( ( C@H ) 2O ) O ) O ) CO ) O ) O ) O ) O Properties Chemical formula C H O Molar mass 342.30 g / mol Appearance white solid Density 1.525 g / cm Melting point 202.8 ° C ( 397.0 ° F ; 475.9 K ) Solubility in water 19.5 g / 100 mL Chiral rotation ( ( α ) ) + 55.4 ° Thermochemistry Std enthalpy of combustion ( Δ H ) 5652 kJ / mol, 1351 kcal / mol, 16.5 kJ / g, 3.94 kcal / g Hazards NFPA 704 0 0 Flash point 357.8 ° C ( 676.0 ° F ; 631.0 K ) Except where otherwise noted, data are given for materials in their standard state ( at 25 ° C ( 77 ° F ), 100 kPa ). N verify ( what is ? ) Infobox references Lactose is a disaccharide sugar composed of galactose and glucose that is found in milk. Lactose makes up around 2 -- 8 % of milk ( by weight ), although the amount varies among species and individuals, and milk with a reduced amount of lactose also exists. It can be extracted from sweet or sour whey. The name comes from lac ( gen. lactis ), the Latin word for milk, plus the - ose ending used to name sugars. It has a formula of C H O and the hydrate formula C H O H O, making it an isomer of sucrose. Contents 1 History 2 Structure and reactions 3 Isolation 4 Metabolism 5 Applications 6 See also 7 References History The first crude isolation of lactose, by Italian physician Fabrizio Bartoletti ( 1576 -- 1630 ), was published in 1633. In 1700, the Venetian pharmacist Lodovico Testi ( 1640 -- 1707 ) published a booklet of testimonials to the power of milk sugar ( saccharum lactis ) to relieve, among other ailments, the symptoms of arthritis. In 1715, Testi 's procedure for making milk sugar was published by Antonio Vallisneri. Lactose was identified as a sugar in 1780 by Carl Wilhelm Scheele. In 1812, Heinrich Vogel ( 1778 -- 1867 ) recognized that glucose was a product of hydrolyzing lactose. In 1856, Louis Pasteur crystallized the other component of lactose, galactose. By 1894, Emil Fischer had established the configurations of the component sugars. Lactose was named by the French chemist Jean Baptiste André Dumas ( 1800 -- 1884 ) in 1843. Structure and reactions The molecular structure of α - lactose, as determined by X-ray crystallography. Lactose is a disaccharide derived from the condensation of galactose and glucose, which form a β - 1 → 4 glycosidic linkage. Its systematic name is β - D - galactopyranosyl - ( 1 → 4 ) - D - glucose. The glucose can be in either the α - pyranose form or the β - pyranose form, whereas the galactose can only have the β - pyranose form : hence α - lactose and β - lactose refer to the anomeric form of the glucopyranose ring alone. Lactose is hydrolysed to glucose and galactose, isomerised in alkaline solution to lactulose, and catalytically hydrogenated to the corresponding polyhydric alcohol, lactitol. Lactose monohydrate crystals have a characteristic tomahawk shape that can be observed with a light microscope. Isolation Several million tons are produced annually as a by - product of the dairy industry. Whey is made up of 6.5 % solids of which 4.8 % is lactose that may be purified by crystallisation. Whey or milk plasma is the liquid remaining after milk is curdled and strained, for example in the production of cheese. Lactose makes up about 2 -- 8 % of milk by weight. Industrially, lactose is produced from whey permeate -- that is whey filtrated for all major proteins. The protein fraction is used in infant nutrition and sport nutrition while the permeate can be evaporated to 60 -- 65 % solids and crystallized while cooling. Lactose can also be precipitated from whey using ethanol. Since it is insoluble in ethanol, lactose precipitates, in about 65 % yield. Metabolism Main article : Lactose intolerance Infant mammals nurse on their mothers to drink milk, which is rich in lactose. The intestinal villi secrete the enzyme called lactase ( β - D - galactosidase ) to digest it. This enzyme cleaves the lactose molecule into its two subunits, the simple sugars glucose and galactose, which can be absorbed. Since lactose occurs mostly in milk, in most mammals, the production of lactase gradually decreases with maturity due to a lack of continuing consumption. Many people with ancestry in Europe, West Asia, South Asia, the Sahel belt in West Africa, East Africa and a few other parts of Central Africa maintain lactase production into adulthood. In many of these areas, milk from mammals such as cattle, goats, and sheep is used as a large source of food. Hence, it was in these regions that genes for lifelong lactase production first evolved. The genes of adult lactose tolerance have evolved independently in various ethnic groups. By descent, more than 70 % of western Europeans can drink milk as adults, compared with less than 30 % of people from areas of Africa, eastern and south - eastern Asia and Oceania. In people who are lactose intolerant, lactose is not broken down and provides food for gas - producing gut flora, which can lead to diarrhea, bloating, flatulence, and other gastrointestinal symptoms. Applications Food industry applications have markedly increased since the 1960s. For example, its bland flavor has lent to its use as a carrier and stabiliser of aromas and pharmaceutical products. Lactose is not added directly to many foods, because its solubility is less than that of other sugars commonly used in food. Infant formula is a notable exception, where the addition of lactose is necessary to match the composition of human milk. Lactose is not fermented by most yeast during brewing, which may be used to advantage. For example, lactose may be used to sweeten stout beer ; the resulting beer is usually called a milk stout or a cream stout. Yeast belonging to the genus Kluyveromyces have a unique industrial application as they are capable of fermenting lactose for ethanol production. Surplus lactose from the whey by - product of dairy operations is a potential source of alternative energy. Another major use of lactose is in the pharmaceutical industry. Lactose is added to pills as a filler because of its physical properties, i.e., compressibility, and low price. For similar reasons it can be used to dilute heroin. See also Lactose intolerance Nectar Sugars in wine lac operon References ^ Jump up to : ( 1 ) Jump up ^ The solubility of lactose in water is 18.9049 g at 25 ° C, 25.1484 g at 40 ° C and 37.2149 g at 60 ° C per 100 g solution. Its solubility in ethanol is 0.0111 g at 40 ° C and 0.0270 g at 60 ° C per 100 g solution. Machado, José J.B. ; Coutinho, João A. ; Macedo, Eugénia A. ( 2001 ), `` Solid -- liquid equilibrium of α - lactose in ethanol / water '' ( PDF ), Fluid Phase Equilibria, 173 ( 1 ) : 121 -- 34, doi : 10.1016 / S0378 - 3812 ( 00 ) 00388 - 5. ds Jump up ^ Sigma Aldrich ^ Jump up to : Carper, Steve. `` The Really BIG List of Lactose Percentages ''. Lactose Intolerance Clearinghouse. Retrieved 30 January 2014. Jump up ^ In 1856, Louis Pasteur named galactose `` lactose ''. See : Pasteur ( 1856 ) `` Note sur le sucre de lait '' ( Note on milk sugar ), Comptes rendus, 42 : 347 -- 351. From page 348 : `` Je propose de le nommer lactose. '' ( I propose to name it lactose. ) In 1860, Berthelot renamed it `` galactose '', and transferred the name `` lactose '' to what is now called lactose. See : Marcellin Berthelot, Chimie organique fondée sur la synthèse ( Organic chemistry based on synthesis ) ( Paris, France : Mallet - Bachelier, 1860 ), vol. 2, pp. 248 -- 249 and pp. 268 -- 270. Jump up ^ Fabrizio Bartoletti, Methodus in dyspnoeam... ( Procedure for asthma... ), ( Bologna ( `` Bononia '' ), ( Italy ) : Nicolò Tebaldini for the heirs of Evangelista Dozza, 1633 ), p. 400. From page 400 : `` Manna seri hæc. Destilla leni balnei calore serum lactis, donec in fundo vasis butyracea fœx subsideat, cui hærebit salina quædam substantia subalbida. Hanc curiose segrega, est enim sal seri essentiale ; seu nitrum, cujus causa nitrosum dicitut serum, huicque tota abstergedi vis inest. Solve in aqua propria, & coagula. Opus repete, donec seri cremorem habeas sapore omnino mannam referentem. '' ( This is the manna of whey. ( Note : `` Manna '' was the dried, sweet sap of the tree Fraxinus ornus. ) Gently distill whey via a heat bath until the buttery scum settles to the bottom of the vessel, to which substance some whitish salt ( i.e., precipitate ) attaches. This curious ( substance once ) separated, is truly the essential salt of whey ; or, on account of which nitre, is called `` nitre of whey '', and all ( life ) force is in this that will be expelled. ( Note : `` Nitre '' was an alchemical concept. It was the power of life, which gave life to otherwise inanimate matter. See the philosophy of Sendivogius. ) Dissolve it in ( its ) own water and coagulate. Repeat the operation until you have cream of whey, recalling, by ( its ) taste, only manna. ) In 1688, the German physician Michael Ettmüller ( 1644 -- 1683 ) reprinted Bartoletti 's preparation. See : Ettmüller, Michael, Opera Omnia... ( Frankfurt am Main ( `` Francofurtum ad Moenum '' ), ( Germany ) : Johann David Zunner, 1688 ), book 2, page 163. From page 163 : `` Undd Bertholetus praeparat ex sero lactis remedium, quod vocat mannam S. ( alchemical symbol for salt, salem ) seri lactis vid. in Encyclopaed. p. 400. Praeparatio est haec :... '' ( Whence Bartoletti prepared from milk whey a medicine, which he called manna or salt of milk whey ; see in ( his ) Encyclopedia ( note : this is a mistake ; the preparation appeared in Bartoletti 's Methodus in dyspnoeam... ), p. 400. This is the preparation :... ) Jump up ^ Lodovico Testi, De novo Saccharo Lactis ( On the new milk sugar ) ( Venice, ( Italy ) : Hertz, 1700 ). Jump up ^ Ludovico Testi ( 1715 ) `` Saccharum lactis '' ( Milk sugar ), Academiae Caesareo - Leopoldinae naturae curiosorum ephemerides,..., 3 : 69 -- 79. The procedure was also published in Giornale de ' letterati d'Italia in 1715. Jump up ^ See : Carl Wilhelm Scheele ( 1780 ) `` Om Mjölk och dess syra '' ( About milk and its acid ), Kongliga Vetenskaps Academiens Nya Handlingar ( New Proceedings of the Royal Academy of Science ), 1 : 116 -- 124. From page 116 : `` Det år bekant, at Ko - mjölk innehåller Smör, Ost, Mjölk - såcker,... '' ( It is known, that cow 's milk contains butter, cheese, milk - sugar,... ) Carl Wilhelm Scheele ( 1780 ) `` Om Mjölk - Såcker - Syra '' ( On milk - sugar acid ), Kongliga Vetenskaps Academiens Nya Handlingar ( New Proceedings of the Royal Academy of Science ), 1 : 269 -- 275. From pages 269 -- 270 : `` Mjölk - Såcker år et sal essentiale, som uti Mjölken finnes uplöst, och som, för dess sötaktiga smak skull, fått namn af såcker. '' ( Milk sugar is an essential salt, which is found dissolved in milk, and which, on account of its sweet taste, has the name of `` sugar ''. ) ^ Jump up to : Linko, P ( 1982 ), `` Lactose and Lactitol '', in Birch, G.G. ; Parker, K.J, Natural Sweeteners, London & New Jersey : Applied Science Publishers, pp. 109 -- 132, ISBN 0 - 85334 - 997 - 5 Jump up ^ See : Vogel ( 1812 ) `` Sur le sucre liquide d'amidon, et sur la transmutation des matières douces en sucre fermentescible '' ( On the liquid sugar of starch, and on the transformation of sweet materials into fermentable sugars ), Annales de chemie et de physique, series 1, 82 : 148 -- 164 ; see especially pages 156 -- 158. H.A. Vogel ( 1812 ) `` Ueber die Verwandlung der Stärke und andrer Körper in Zucker '' ( On the conversion of starches and other substances into sugar ), Annalen der Physik, new series, 42 : 123 -- 134 ; see especially pages 129 -- 131. Jump up ^ Pasteur ( 1856 ) `` Note sur le sucre de lait '' ( Note on milk sugar ), Comptes rendus, 42 : 347 -- 351. Jump up ^ Fischer determined the configuration of glucose in : Emil Fischer ( 1891 ) `` Ueber die Configuration des Traubenzuckers und seiner Isomeren '' ( On the configuration of grape sugar and its isomers ), Berichte der Deutschen Chemischen Gesellschaft, 24 : 1836 -- 1845. Emil Fischer ( 1891 ) `` Ueber die Configuration des Traubenzuckers und seiner Isomeren. II '' ( On the configuration of grape sugar and its isomers ), Berichte der Deutschen Chemischen Gesellschaft, 24 : 2683 -- 2687. Fischer established the configuration of galactose in : Emil Fischer and Robert S. Morrell ( 1894 ) `` Ueber die Configuration der Rhamnose und Galactose '' ( On the configuration of rhamnose and galactose ), Berichte der Deutschen chemischen Gesellschaft zu Berlin, 27 : 382 -- 394. The configuration of galactose appears on page 385. Jump up ^ Dumas, Traité de Chimie, Appliquée aux Arts, volume 6 ( Paris, France : Bechet Jeune, 1843 ), p. 293. Jump up ^ Ranken, M.D. ; Kill, R.C. ( 1997 ), Food industries manual, Springer, p. 125, ISBN 0 - 7514 - 0404 - 7 Jump up ^ Wong SY, Hartel RW. : Crystallization in lactose refining - a review. J Food Sci 2014, 79 ( 3 ) : R257 - 72. ( 2 ) Jump up ^ Minard, R. Introduction to Organic Laboratory Techniques : A Microscale Approach. Pavia, Lampman, Kriz & Engel, Saunders. 1990. Jump up ^ Wade, Nicholas ( 2006 - 12 - 10 ), `` Study Detects Recent Instance of Human Evolution '', New York Times. Jump up ^ Ridley, Matt ( 1999 ), Genome, HarperCollins, p. 193, ISBN 978 - 0 - 06 - 089408 - 5. Jump up ^ Ling, Charles ( 2008 ), Whey to Ethanol : A Biofuel Role for Dairy Cooperatives ? ( PDF ). Types of carbohydrates General Aldose Ketose Furanose Pyranose Geometry Anomer Cyclohexane conformation Mutarotation Monosaccharides Dioses Aldodiose Glycolaldehyde Trioses Aldotriose Glyceraldehyde Ketotriose Dihydroxyacetone Tetroses Aldotetroses Erythrose Threose Ketotetrose Erythrulose Pentoses Aldopentoses Arabinose Lyxose Ribose Xylose Ketopentoses Ribulose Xylulose Deoxy sugars Deoxyribose Hexoses Aldohexoses Allose Altrose Galactose Glucose Gulose Idose Mannose Talose Ketohexoses Fructose Psicose Sorbose Tagatose Deoxy sugars Fucose Fuculose Rhamnose Heptoses Ketoheptoses Mannoheptulose Sedoheptulose Above 7 Octoses Nonoses Neuraminic acid Multiple Disaccharides Cellobiose Isomaltose Lactose Lactulose Maltose Sucrose Trehalose Turanose Trisaccharides Maltotriose Melezitose Raffinose Tetrasaccharides Stachyose Other oligosaccharides Acarbose Fructooligosaccharide ( FOS ) Galactooligosaccharide ( GOS ) Isomaltooligosaccharide ( IMO ) Maltodextrin Mannan - oligosaccharides ( MOS ) Polysaccharides Beta - glucan Oat beta - glucan Lentinan Sizofiran Zymosan Cellulose Chitin Chitosan Dextrin / Dextran Fructose / Fructan Inulin Galactose / Galactan Glucose / Glucan Glycogen Hemicellulose Levan beta 2 → 6 Lignin Mannan Pectin Starch Amylopectin Amylose Xanthan gum Sugar ( as food commodity ) List of sugars and sugar products Chemistry Fructose Galactose Glucose Lactose Maltose Sucrose Trehalose Xylose Monosaccharide Disaccharide Free sugar Reducing sugar Sources Sugar beet Sugarcane Agave nectar Birch Coconut Date Honeydew Maple Palm Products Syrups Candi sugar Cheong Maesil - cheong Mogwa - cheong Yuja - cheong Corn syrup Glucose syrup Golden syrup High - fructose corn syrup High - maltose corn syrup Honey Inverted sugar syrup Kuromitsu Maple syrup Molasses Pine honey Steen 's cane syrup Treacle Solid forms Brown Peen tong Chancaca Crystalline fructose Gelling Gula melaka Jaggery Misri Mizuame Molasses sugar Muscovado Nib Non-centrifugal cane sugar Panela Plantation Reserve Powdered Preserving Rock candy Sucanat Sugar candy Barley sugar Butterscotch Candy Hard Toffee Sugar glass Sugarloaf Wasanbon Other forms Caramel Cotton candy floss Maple sugar foods Rum Sugar alcohol Sugar confectionery Sugarcane juice Tuzemák Unrefined sweeteners Industry Production Boilery Plantation Casa grande Refinery Sugar bush Sugar cane mill Engenho Batey Zafra By region ( current ) Cuba Caribbean Philippines Sri Lanka U.S. Sugar Program By region ( historical ) Danish West Indies Fiji Hawaii History Amelioration Act 1798 Blackbirding Colonial molasses trade Demerara rebellion of 1823 Holing cane Molasses Act Reciprocity Treaty of 1875 Slavery in the British and French Caribbean Sugar Act Sugar Duties Act 1846 Sugar Intervention Taiwan Sugar Railways Triangular trade Culture Crop over Sugar house Sugaring Sugar nips Sugar packet Sucrology Sugar people Sugar tit Sugar sculpture Treacle mine Related Added sugar Australian Aboriginal sweet foods Bagasse Barley malt syrup Brown rice syrup Cane knife Flavored syrup Fruit syrup Date honey Grape Jallab Health effects Nectar Sugar addiction Sugars in wine Residual sugar Sugar substitute Sweetened beverage Sweetener Sweetness Vinasse Yacón syrup Production GND : 4166380 - 9 NDL : 00568767 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Lactose&oldid=808334227 '' Categories : Disaccharides Excipients Sugar substitutes Hidden categories : Articles without KEGG source ECHA InfoCard ID from Wikidata Articles with changed FDA identifier Articles containing unverified chemical infoboxes Articles containing Latin - language text Wikipedia articles with GND identifiers Talk Contents About Wikipedia বাংলা Беларуская Беларуская ( тарашкевіца ) ‎ Български Bosanski Català Čeština Cymraeg Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge Galego 한국어 Հայերեն Hrvatski Bahasa Indonesia Interlingua Íslenska Italiano עברית ქართული Latina Latviešu Lietuvių Magyar Македонски Malagasy Bahasa Melayu Nederlands 日本 語 Norsk Norsk nynorsk Occitan Oʻzbekcha / ўзбекча Polski Português Română Русский Scots Shqip Simple English Slovenčina Slovenščina کوردی Српски / srpski Srpskohrvatski / српскохрватски Basa Sunda Suomi Svenska தமிழ் ไทย Türkçe Українська Tiếng Việt 粵語 中文 Edit links This page was last edited on 2 November 2017, at 07 : 10. 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Question: what are the products of the breakdown of lactose
Answer: glucose