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Revision as of 07:21, 18 February 2012 editBeetstra (talk | contribs)Edit filter managers, Administrators172,074 edits Saving copy of the {{chembox}} taken from revid 474541488 of page Lactose for the Chem/Drugbox validation project (updated: 'ChEMBL').		Latest revision as of 21:14, 21 January 2025 edit Moonreach (talk | contribs)Extended confirmed users2,069 editsm →Structure and reactions
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			{{short description|Carbohydrate}}
	{{ambox | text = This page contains a copy of the infobox ({{tl|chembox}}) taken from revid of page ] with values updated to verified values.}}
	{{chembox		{{Chembox
	| Verifiedfields = changed		| Verifiedfields = changed
	| Watchedfields = changed		| Watchedfields = changed
	| verifiedrevid = 400128939		| verifiedrevid = 477497006
	| Name = Lactose (Milk sugar)		| Name = Lactose
			| ImageFile_Ref = {{chemboximage|correct|??}}
	| ImageFile = Beta-D-Lactose.svg		| ImageFile = Beta-D-Lactose.svg
	| ImageSize = 300px		| ImageSize = 200px
			| ImageClass = skin-invert-image
	| IUPACName = β-<small>D</small>-galactopyranosyl-(1→4)-<small>D</small>-glucose
	| OtherNames = Milk sugar<br/>4-''O''-β-<small>D</small>-galactopyranosyl-<small>D</small>-glucose		| IUPACName = β-<small>D</small>-Galactopyranosyl-(1→4)-<small>D</small>-glucose
			| SystematicName = (2''R'',3''R'',4''S'',5''R'',6''S'')-2-(Hydroxymethyl)-6-<nowiki/>{oxy}oxane-3,4,5-triol
	| Section1 = {{Chembox Identifiers
			| OtherNames = Milk sugar<br />Lactobiose<br />4-''O''-β-<small>D</small>-Galactopyranosyl-<small>D</small>-glucose
	| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
			|Section1={{Chembox Identifiers
			| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
	| ChemSpiderID = 5904		| ChemSpiderID = 5904
	| 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		| 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
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	| StdInChIKey = GUBGYTABKSRVRQ-DCSYEGIMSA-N		| StdInChIKey = GUBGYTABKSRVRQ-DCSYEGIMSA-N
	| CASNo = 63-42-3		| CASNo = 63-42-3
	| CASNo_Ref = {{cascite|correct|CAS}}		| CASNo_Ref = {{cascite|correct|CAS}}
	| EC-number = 200-559-2		| EC_number = 200-559-2
	| PubChem = 6134		| KEGG = C01970
			| PubChem = 6134
	| ChEMBL_Ref = {{ebicite|changed|EBI}}
			| ChEMBL_Ref = {{ebicite|correct|EBI}}
	| ChEMBL = <!-- blanked - oldvalue: 1159651 -->
			| ChEMBL = 417016
	| UNII_Ref = {{fdacite|changed|FDA}}
	| UNII = J2B2A4N98G		| Gmelin = 342369
			| Beilstein = 90841
	| ChEBI_Ref = {{ebicite|changed|EBI}}
			| UNII_Ref = {{fdacite|correct|FDA}}
			| UNII = 3SY5LH9PMK
			| ChEBI_Ref = {{ebicite|correct|EBI}}
	| ChEBI = 36218		| ChEBI = 36218
	| SMILES = C(1((((O1)O2(O((2O)O)O)CO)O)O)O)O		| SMILES = C(1((((O1)O2(O((2O)O)O)CO)O)O)O)O
	}}		}}
	| Section2 = {{Chembox Properties		|Section2={{Chembox Properties
			| C=12 | H=22 | O=11
	| Formula = C<sub>12</sub>H<sub>22</sub>O<sub>11</sub>
	| MolarMass = 342.30 g/mol		| Appearance = White solid
			| Density = 1.525{{nbsp}}g/cm<sup>3</sup>
	| Appearance = white solid
			| MeltingPt = 252&nbsp;°C (anhydrous)<ref name="DoC">{{cite book | author=Peter M. Collins | title=Dictionary of Carbohydrates | edition=2nd | year=2006 | publisher=Chapman & Hall/CRC | location=Boca Raton | isbn=978-0-8493-3829-8 | page=677}}</ref> <br /> 202 °C (monohydrate)<ref name="DoC"/>
	| Density = 1.525 g/cm<sup>3</sup>
			| MeltingPt_ref =
	| MeltingPt = 202.8&nbsp;°C<ref name=Ald>Anonymous. Sigma Aldrich. Lactose Product. http://www.sigmaaldrich.com/catalog/ProductDetail.do?lang=en&N4=17814|FLUKA&N5=SEARCH_CONCAT_PNO|BRAND_KEY&F=SPEC St. Louis MO.</ref>
			| Solubility = 195{{nbsp}}g/L<ref name=PubChem>{{Cite web | url=https://pubchem.ncbi.nlm.nih.gov/compound/440995#section=Experimental-Properties | title=D-Lactose}}</ref><ref>The solubility of lactose in water is 189.049&nbsp;g at 25&nbsp;°C, 251.484&nbsp;g at 40&nbsp;°C and 372.149&nbsp;g at 60&nbsp;°C per kg solution. Its solubility in ] is 0.111&nbsp;g at 40&nbsp;°C and 0.270&nbsp;g at 60&nbsp;°C per kg solution.{{citation | year = 2001 | last1 = Machado | first1 = José J. B. | first2 = João A. | last2 = Coutinho | first3 = Eugénia A. | last3 = Macedo | title = Solid–liquid equilibrium of α-lactose in ethanol/water | url = http://path.web.ua.pt/file/FPE%20(2000)%20173%20121.pdf | journal = Fluid Phase Equilibria | volume = 173 | issue = 1 | pages = 121–34 | doi = 10.1016/S0378-3812(00)00388-5}}.
	| BoilingPt = 668.9&nbsp;°C<ref name=Ald/>
	| Solubility = 21.6 g/100 mL<ref>The solubility of lactose in water is 18.9049&nbsp;g at 25&nbsp;°C, 25.1484&nbsp;g at 40&nbsp;°C and 37.2149&nbsp;g at 60&nbsp;°C per 100&nbsp;g solution. Its solubility in ] is 0.0111&nbsp;g at 40&nbsp;°C and 0.0270&nbsp;g at 60&nbsp;°C per 100&nbsp;g solution.{{citation | year = 2001 | last1 = Machado | first1 = José J. B. | first2 = João A. | last2 = Coutinho | first3 = Eugénia A. | last3 = Macedo | title = Solid–liquid equilibrium of α-lactose in ethanol/water | url = http://path.web.ua.pt/file/FPE%20(2000)%20173%20121.pdf | journal = Fluid Phase Equilibria | volume = 173 | issue = 1 | pages = 121–34 | doi = 10.1016/S0378-3812(00)00388-5}}.
	ds</ref>		ds</ref>
			| SpecRotation = +55.4° (anhydrous)<br />+52.3° (monohydrate)
	}}		}}
	| Section4 = {{Chembox Thermochemistry| DeltaHc = 5652 kJ/mol, 1351 kcal/mol, 16.5 kJ/g, 3.94 kcal/g}}		|Section4={{Chembox Thermochemistry| DeltaHc = 5652{{nbsp}}kJ/mol, 1351{{nbsp}}kcal/mol, 16.5{{nbsp}}kJ/g, 3.94{{nbsp}}kcal/g}}
	| Section7 = {{Chembox Hazards		|Section7={{Chembox Hazards
	| EUIndex = not listed		| FlashPtC = 357.8
			| FlashPt_ref = <ref name=Ald></ref>
	| FlashPt = 357.8&nbsp;°C<ref name="Ald"/>
	| Autoignition =		| AutoignitionPtC =
			| NFPA-H = 0
			| NFPA-F = 0
			| NFPA-R = 0
	}}		}}
	}}		}}
			'''Lactose''', or '''milk sugar''', is a ] composed of ] and ] and has the ] C<sub>12</sub>H<sub>22</sub>O<sub>11</sub>. Lactose makes up around 2–8% of ] (by mass). The name comes from {{lang|la|lact}} (gen.&nbsp;{{lang|la|lactis}}), the ] word for milk, plus the suffix '']'' used to name sugars. The compound is a white, ], non-] solid with a mildly sweet taste. It is used in the food industry.<ref name=Ull>{{cite encyclopedia|encyclopedia=Ullmann's Encyclopedia of Industrial Chemistry|author=Gerrit M. Westhoff |author2=Ben F.M. Kuster |author3=Michiel C. Heslinga |author4=Hendrik Pluim |author5=Marinus Verhage |year=2014|pages=1–9|doi= 10.1002/14356007.a15_107.pub2|publisher=Wiley-VCH|chapter=Lactose and Derivatives|isbn=978-3-527-30673-2}}</ref>
			==Structure and reactions==
			].]]
			]]]
			Lactose is a ] composed of ] and ], which form a β-1→4 ] linkage. Its ] is β-<small>D</small>-galactopyranosyl-(1→4)-<small>D</small>-glucose. The glucose can be in either the α-] form or the β-pyranose form, whereas the galactose can have only the β-pyranose form: hence α-lactose and β-lactose refer to the ]ic form of the glucopyranose ring alone. Detection reactions for lactose are the Wöhlk-<ref>{{Cite journal |last1=Ruppersberg |first1=Klaus |last2=Blankenburg |first2=Janet |date=2018 |title=150 Years Alfred Wöhlk |url=http://www.chemistryviews.org/details/education/10821368/150_Years_Alfred_Wohlk.html |journal=ChemViews |doi=10.1002/chemv.201800002}}</ref> and Fearon's test.<ref>{{Cite journal |last=Fearon |first=W. R. |date=1942 |title=The detection of lactose and maltose by means of methylamine |url=http://xlink.rsc.org/?DOI=an9426700130 |journal=The Analyst |language=en |volume=67 |issue=793 |page=130 |doi=10.1039/an9426700130 |issn=0003-2654}}</ref> They can be used to detect the different lactose content of ] such as ], ], ], ], ], ], ], etc.<ref>{{Cite journal |last1=Ruppersberg |first1=Klaus |last2=Herzog |first2=Stefanie |last3=Kussler |first3=Manfred W. |last4=Parchmann |first4=Ilka |date=2019-10-17 |title=How to visualize the different lactose content of dairy products by Fearon's test and Woehlk test in classroom experiments and a new approach to the mechanisms and formulae of the mysterious red dyes |journal=] |volume=2 |issue=2 |doi=10.1515/cti-2019-0008 |issn=2569-3263 |s2cid=208714341 |doi-access=free}}</ref>
			Lactose is ] to glucose and galactose, ] in ] solution to ], and ] ] to the corresponding ], ].<ref name="Linko1981"/> Lactulose is a commercial product, used for treatment of ].{{cn|date=May 2024}}
			==Occurrence and isolation==
			Lactose comprises about 2–8% of milk by weight. Several million tons are produced annually as a by-product of the ].{{cn|date=May 2024}}
			] or milk plasma is the liquid remaining after milk is curdled and strained, for example in the production of ]. Whey is made up of 6.5% solids, of which 4.8% is lactose, which is purified by crystallisation.<ref>{{Citation |last1=Ranken |first1=M. D. |title=Food industries manual |url=https://archive.org/details/foodindustriesma0000unse |page=125 |year=1997 |publisher=Springer |isbn=978-0-7514-0404-3 |last2=Kill |first2=R. C.}}</ref> Industrially, lactose is produced from whey permeate – whey filtrated for all major ]s. The protein fraction is used in ] and ] while the permeate can be evaporated to 60–65% solids and crystallized while cooling.<ref>{{citation |last1=Wong |first1=S. Y. |title=Crystallization in lactose refining-a review |journal=] |volume=79 |issue=3 |pages=R257–72 |year=2014 |doi=10.1111/1750-3841.12349 |pmid=24517206 |last2=Hartel |first2=R. W.|doi-access=free }}, DOI is open access</ref> Lactose can also be isolated by dilution of whey with ].<ref>{{citation |title=Introduction to Organic Laboratory Techniques: A Microscale Approach |first1=Donald L. |last1=Pavia |first2=Gary M. |last2=Lampman |first3=George S. |last3=Kriz |publisher=Saunders |year=1990 |isbn=0-03-014813-8 }}</ref>
			Dairy products such as ] and cheese contain very little lactose. This is because the bacteria used to make these products breaks down lactose through the use of ].{{cn|date=May 2024}}
			==Metabolism==
			{{See also|Lactose intolerance|Lactase persistence}}
			Infant ]s nurse on their mothers to drink milk, which is rich in lactose. The ] secrete the ] ] (β-D-galactosidase) to digest it. This enzyme cleaves the lactose molecule into its two subunits, the simple ]s 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 weaning; the removal of lactose from the diet removes the metabolic pressure to continue to produce lactase for its digestion.{{cn|date=May 2024}}
			Many people with ancestry in ], ], ], the ] belt in ], ] and a few other parts of ] maintain lactase production into adulthood due to selection for genes that continue lactase production. In many of these areas, milk from mammals such as ], ], and ] is used as a large source of food. Hence, it was in these regions that genes for lifelong lactase production first ]. The genes of adult lactose tolerance have evolved independently in various ethnic groups.<ref>{{citation | first = Nicholas | last = Wade | title= Study Detects Recent Instance of Human Evolution | date = 2006-12-10 | newspaper= New York Times | url= https://www.nytimes.com/2006/12/10/science/10cnd-evolve.html?}}.</ref> By descent, more than 70% of western Europeans can digest lactose as adults, compared with less than 30% of people from areas of Africa, eastern and south-eastern Asia and Oceania.<ref>{{Citation |last= Ridley |first= Matt |title= Genome |publisher= ] |year= 1999 |page= 193 |isbn= 978-0-06-089408-5}}.</ref> In people who are lactose intolerant, lactose is not broken down and provides food for gas-producing ], which can lead to diarrhea, bloating, flatulence, and other gastrointestinal symptoms.
			==Biological properties==
			The ] of lactose is 0.2 to 0.4, relative to 1.0 for ].<ref name="Schaafsma2008">{{cite journal |last1=Schaafsma |first1=Gertjan |year=2008 |title=Lactose and lactose derivatives as bioactive ingredients in human nutrition |url=http://pdfs.semanticscholar.org/a45b/ce8eb621c78f163ec94f6e2c5add17a624e4.pdf |journal=International Dairy Journal |volume=18 |issue=5 |pages=458–465 |doi=10.1016/j.idairyj.2007.11.013 |s2cid=10346203 |issn=0958-6946 |archive-url=https://web.archive.org/web/20190302135517/http://pdfs.semanticscholar.org/a45b/ce8eb621c78f163ec94f6e2c5add17a624e4.pdf |archive-date=Mar 2, 2019}}</ref> For comparison, the sweetness of glucose is 0.6 to 0.7, of ] is 1.3, of galactose is 0.5 to 0.7, of ] is 0.4 to 0.5, of ] is 0.4, and of ] is 0.6 to 0.7.<ref name="Schaafsma2008" />
			When lactose is completely digested in the ], its ] is 4 kcal/g, or the same as that of other ]s.<ref name="Schaafsma2008" /> However, lactose is not always fully digested in the small intestine. Depending on ingested dose, combination with meals (either solid or liquid), and lactase activity in the ]s, the caloric value of lactose ranges from 2 to 4 kcal/g.<ref name="Schaafsma2008" /> Undigested lactose acts as ]. It also has positive effects on absorption of ]s, such as ] and ].<ref name="Schaafsma2008" />
			The ] of lactose is 46 to 65.<ref name="BjörckLiljeberg2000">{{cite journal |last1=Björck |first1=Inger |last2=Liljeberg |first2=Helena |last3=Östman |first3=Elin |year=2000 |title=Low glycaemic-index foods |journal=British Journal of Nutrition |volume=83 |issue=S1 |pages=S149–S155 |doi=10.1017/S0007114500001094 |issn=0007-1145 |pmid=10889806 |s2cid=14574754 |doi-access=free}}</ref> For comparison, the glycemic index of glucose is 100 to 138, of sucrose is 68 to 92, of maltose is 105, and of fructose is 19 to 27.<ref name="Schaafsma2008" /><ref name="BjörckLiljeberg2000" />
			Lactose has relatively low ] among sugars.<ref name="MillerJarvis2006">{{cite book|author1=Gregory D. Miller|author2=Judith K. Jarvis|author3=Lois D. McBean|title=Handbook of Dairy Foods and Nutrition|url=https://books.google.com/books?id=5tleQ0aLJvoC&pg=PA248|date=15 December 2006|publisher=CRC Press|isbn=978-1-4200-0431-1|pages=248–}}</ref> This is because it is not a substrate for ] formation and it is not rapidly ] by ] ].<ref name="MillerJarvis2006" /> The buffering capacity of milk also reduces the cariogenicity of lactose.<ref name="Schaafsma2008" />
			==Applications==
			Its mild flavor and easy handling properties have led to its use as a carrier and stabiliser of aromas and pharmaceutical products.<ref name=Ull/> Lactose is not added directly to many foods, because its solubility is less than that of other sugars commonly used in food. ] is a notable exception, where the addition of lactose is necessary to match the composition of human milk.{{cn|date=May 2024}}
			Lactose is not fermented by most ] during brewing, which may be used to advantage.<ref name=Linko1981/> For example, lactose may be used to sweeten stout beer; the resulting beer is usually called a ] or a cream stout.
			Yeast belonging to the genus '']'' 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.<ref>{{citation |last=Ling |first=Charles |title=Whey to Ethanol: A Biofuel Role for Dairy Cooperatives? |date=2008 |url=http://www.rd.usda.gov/files/RR214.pdf |publisher=United States Department of Agriculture Rural Development}}.</ref>
			Another significant lactose use is in the pharmaceutical industry. Lactose is added to tablet and capsule drug products as an ingredient because of its physical and functional properties (examples are ], ] or ] among many others).<ref name=Ull/><ref>{{Cite journal |last=Zdrojewicz |first=Z. |last2=Zyskowska |first2=K. |last3=Wasiuk |first3=S. |date=2018 |title=Lactose in drugs and lactose intolerance – realities and myths |url=https://pimr.pl/index.php/issues/2018-vol-14-no-3/lactose-in-drugs-and-lactose-intolerance-realities-and-myths |journal=Paediatrics and Family Medicine |volume=14 |issue=3 |pages=261–266 |doi=10.15557/PiMR.2018.0027|doi-access=free }}</ref> For similar reasons, it can be used to dilute illicit drugs such as cocaine or heroin.<ref>{{Cite journal |last1=Rinaldi |first1=R. |last2=Negro |first2=F. |last3=Minutillo |first3=A. |date=2020-02-20 |title=The health threat of new synthetic opioids as adulterants of classic drugs of abuse |url=http://www.clinicaterapeutica.it/2020/171/2/05_MINUTILLO.pdf |journal=La Clinica Terapeutica |volume=171 |issue=2 |pages=107–109 |doi=10.7417/CT.2020.2198 |issn=1972-6007 |pmid=32141480}}</ref>
			==History==
			The first crude isolation of lactose, by Italian physician Fabrizio Bartoletti (1576–1630), was published in 1633.<ref>Fabrizio Bartoletti, ''{{Lang|la|Methodus in dyspnoeam}}'' ... , (Bologna ("Bononia"), (Italy): Nicolò Tebaldini for the heirs of Evangelista Dozza, 1633), From page 400: ''"''{{Lang|la|Manna|italic=no}}'' {{Lang|la|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. ]''.] Gently distill whey via a heat bath until the buttery scum settles to the bottom of the vessel, to which substance some whitish salt attaches. This curious separated, is truly the essential salt of whey; or, on account of which nitre, is called "nitre of whey", and all force is in this that will be expelled. ].] Dissolve it in own water and coagulate. Repeat the operation until you have cream of whey, recalling, by taste, only manna.)<br />
			In 1688, the German physician ] (1644–1683) reprinted Bartoletti's preparation. See: Ettmüller, Michael, ''Opera Omnia'' ... (Frankfurt am Main ("Francofurtum ad Moenum"), : Johann David Zunner, 1688), book 2, {{Webarchive|url=https://web.archive.org/web/20181109143338/http://digital.slub-dresden.de/werkansicht/dlf/79899/913/1/cache.off|date=2018-11-09}} From page 163: ''"Undd ''Bertholetus'' praeparat ex sero lactis remedium, quod vocat ''mannam'' S. ''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 ''Encyclopedia'' , p. 400. This is the preparation: ... )</ref> In 1700, the Venetian pharmacist Lodovico Testi (1640–1707) published a booklet of testimonials to the power of milk sugar (''{{Lang|la|saccharum lactis}}'') to relieve, among other ailments, the symptoms of arthritis.<ref>Lodovico Testi, (Venice, (Italy): Hertz, 1700).</ref> In 1715, Testi's procedure for making milk sugar was published by Antonio Vallisneri.<ref>Ludovico Testi (1715) (Milk sugar), ''Academiae Caesareo-Leopoldinae naturae curiosorum ephemerides'', ... , '''3''' : 69–79. The procedure was also published in ''Giornale de' letterati d'Italia'' in 1715.</ref> Lactose was identified as a sugar in 1780 by ].<ref>See:
			* Carl Wilhelm Scheele (1780) (About milk and its acid), ''{{Lang|sv|Kongliga Vetenskaps Academiens Nya Handlingar}}'' (New Proceedings of the Royal Academy of Science), '''1''' : 116–124. From page 116: ''"{{Lang|sv|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) (On milk-sugar acid), ''{{Lang|sv|Kongliga Vetenskaps Academiens Nya Handlingar}}'' (New Proceedings of the Royal Academy of Science), '''1''' : 269–275. From pages 269–270: ''"{{Lang|sv|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".)</ref><ref name="Linko1981">{{citation |author1=Linko, P |title=Natural Sweeteners |url=https://archive.org/details/nutritivesweeten0000unse |pages=109–132 |year=1982 |editor1=Birch, G.G. |chapter=Lactose and Lactitol |place=London & New Jersey |publisher=Applied Science Publishers |isbn=978-0-85334-997-6 |editor2=Parker, K.J}}</ref>
			In 1812, Heinrich Vogel (1778–1867) recognized that glucose was a product of hydrolyzing lactose.<ref>See:
			* Vogel (1812) (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) (On the conversion of starches and other substances into sugar), ''Annalen der Physik'', new series, '''42''' : 123–134; see especially pages 129–131.</ref> In 1856, ] crystallized the other component of lactose, galactose.<ref>Pasteur (1856) (Note on milk sugar), ''Comptes rendus'', '''42''' : 347–351.</ref> By 1894, ] had established the configurations of the component sugars.<ref>Fischer determined the configuration of glucose in:
			* Emil Fischer (1891) (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) (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.</ref>
			Lactose was named by the French chemist ] (1800–1884) in 1843.<ref>Dumas, ''Traité de Chimie, Appliquée aux Arts'', volume 6 (Paris, France: Bechet Jeune, 1843), </ref> In 1856, Pasteur named galactose "lactose".<ref>Pasteur (1856) (Note on milk sugar), ''Comptes rendus'', '''42''' : 347–351. From page 348: ''"Je propose de le nommer ''lactose''."'' (I propose to name it ''lactose''.)</ref> In 1860, ] renamed it "galactose", and transferred the name "lactose" to what is now called lactose.<ref>Marcellin Berthelot, ''Chimie organique fondée sur la synthèse'' (Paris, France: Mallet-Bachelier, 1860), vol. 2, and </ref> It has a formula of C<sub>12</sub>H<sub>22</sub>O<sub>11</sub> and the hydrate formula C<sub>12</sub>H<sub>22</sub>O<sub>11</sub>·H<sub>2</sub>O, making it an ] of sucrose.
			==See also==
			* ]
			* ]
			* ]
			* ]
			* ]
			==References==
			{{Reflist}}
			==External links==
			* {{Commons category-inline}}
			{{Carbohydrates}}
			{{Sugar}}
			{{Authority control}}
			]
			]
			]