https://wiki.sarg.dev/api.php?action=feedcontributions&feedformat=atom&user=2405%3A4802%3A1CAA%3AEE20%3A85A3%3ACD57%3AADBD%3A3944Vero - Wikipedia - User contributions [en]2026-08-14T19:49:03ZUser contributionsMediaWiki 1.44.2https://wiki.sarg.dev/index.php?title=Maltose&diff=147639Maltose2025-10-27T17:09:32Z<p>2405:4802:1CAA:EE20:85A3:CD57:ADBD:3944: </p>
<hr />
<div>{{Use dmy dates|date=March 2018}}<br />
{{chembox<br />
| Verifiedfields = changed<br />
| Watchedfields = removed<br />
| verifiedrevid = 47716923<br />
| ImageFile = Maltose2.svg<br />
| ImageSize = <br />
| ImageName = α-Maltose<br />
| ImageCaption = α-Maltose<br />
| ImageClass = skin-invert-image<br />
| ImageFile1 = Maltose structure.svg<br />
| ImageSize1 = <br />
| ImageName1 = β-Maltose<br />
| ImageCaption1 = β-Maltose<br />
| ImageClass1 = skin-invert-image<br />
| IUPACName = α-{{sm|d}}-Glucopyranosyl-(1→4)-β-{{sm|d}}-glucopyranose<br><br />
4-''O''-α-<small>D</small>-Glucopyranosyl-<small>D</small>-glucopyranose<br />
| OtherNames = <br />
| SystematicName = (3''R'',4''R'',5''S'',6''R'')-6-(hydroxymethyl)-5-{{(}}[(2''R'',3''R'',4''S'',5''S'',6''R'')-3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxy}oxane-2,3,4-triol<br />
| Section1 = {{Chembox Identifiers<br />
| ChEBI_Ref = {{ebicite|correct|EBI}}<br />
| ChEBI = 17306<br />
| SMILES = O([C@H]1[C@H](O)[C@@H](O)C(O)O[C@@H]1CO)[C@H]2O[C@@H]([C@@H](O)[C@H](O)[C@H]2O)CO<br />
| UNII_Ref = {{fdacite|correct|FDA}}<br />
| UNII = 66Y63L379N<br />
| KEGG = D00044<br />
| ChEMBL_Ref = {{ebicite|changed|EBI}}<br />
| ChEMBL = 1234209<br />
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}<br />
| StdInChI = 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<br />
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}<br />
| StdInChIKey = GUBGYTABKSRVRQ-PICCSMPSSA-N<br />
| ChemSpiderID1_Ref = {{chemspidercite|correct|chemspider}}<br />
| ChemSpiderID1 = 6019<br />
| ChemSpiderID1_Comment = β-maltose<br />
| 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<br />
| InChIKey1 = GUBGYTABKSRVRQ-PICCSMPSSA-N<br />
| CASNo = 69-79-4<br />
| CASNo_Ref = {{cascite|correct|CAS}}<br />
| CASNoOther =<br />
| EC_number = 200-716-5<br />
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}<br />
| ChemSpiderID = 388469<br />
| ChemSpiderID_Comment = α-maltose<br />
| PubChem = 6255<br />
}}<br />
| Section2 = {{Chembox Properties<br />
| Properties_ref = <ref>{{RubberBible62nd|page=C-367}}.</ref><br />
| C=12 | H=22 | O=11<br />
| Appearance = White powder or crystals<br />
| Density = 1.54 g/cm<sup>3</sup><br />
| MeltingPtC = 160 to 165<br />
| MeltingPt_notes = (anhydrous)<br />102–103&nbsp;°C (monohydrate)<br />
| Solubility = 1.080 g/mL (20&nbsp;°C)<br />
| SpecRotation = +140.7° (H<sub>2</sub>O, ''c'' = 10)<br />
}}<br />
| Section7 = {{Chembox Hazards<br />
| ExternalSDS = [https://www.merckmillipore.com/INTERSHOP/web/WFS/Merck-GB-Site/en_US/-/GBP/ProcessMSDS-Start?PlainSKU=MDA_CHEM-105912&ReferrerURL=https%3A%2F%2Fwww.google.co.uk%2F&Origin=SERP&bd=1 External MSDS]<br />
| AutoignitionPt =<br />
}}<br />
| Section8 = {{Chembox Related<br />
| OtherFunction = [[Sucrose]]<br />[[Lactose]]<br />[[Trehalose]]<br />[[Cellobiose]]<br />
}}<br />
}}<br />
[[Image:Amylase reaction.png|thumb|right|260px|Amylase reaction consisting of hydrolyzing amylose, producing maltose]]<br />
<br />
'''Maltose''' ({{IPAc-en|ˈ|m|ɔː|l|t|oʊ|s}}<ref>Dictionary Reference: [http://dictionary.reference.com/browse/maltose maltose]</ref> or {{IPAc-en|ˈ|m|ɔː|l|t|oʊ|z}}<ref>Cambridge dictionary: [http://dictionary.cambridge.org/dictionary/british/maltose maltose]</ref>), also known as '''maltobiose''' or '''malt sugar''', is a [[disaccharide]] formed from two units of [[glucose]] joined with an α(1→4) [[glycosidic bond|bond]]. In the [[isomer]] [[isomaltose]], the two glucose molecules are joined with an α(1→6) bond. Maltose is the two-unit member of the [[amylose]] [[homologous series]], the key structural motif of [[starch]]. When [[beta-amylase]] breaks down starch, it removes two glucose units at a time, producing maltose. An example of this reaction is found in [[germination|germinating]] seeds, which is why it was named after [[malt]].<ref name=Stoker>{{Cite book|url=https://books.google.com/books?id=HRCdBQAAQBAJ&pg=PA278|title=Organic and Biological Chemistry|last=Stoker|first=H. Stephen|date=2015-01-02|publisher=Cengage Learning|isbn=9781305686458|language=en}}</ref> Unlike [[sucrose]], it is a [[reducing sugar]].<ref name="Fruton">{{cite book|last1=Fruton|first1=Joseph S|title=Proteins, Enzymes, Genes: The Interplay of Chemistry and Biology|date=1999|publisher=Yale University Press|location=Chelsea, Michigan|isbn=0300153597|page=144|url=https://books.google.com/books?id=X6skaZlZNdsC&pg=PA144|access-date=21 October 2017|language=en}}</ref><br />
<br />
== History ==<br />
Maltose was discovered by [[Augustin-Pierre Dubrunfaut]], although this discovery was not widely accepted until it was confirmed in 1872 by Irish chemist and brewer [[Cornelius O'Sullivan]].<ref name="Fruton" /><ref>{{cite journal|last1=O'Sullivan|first1=Cornelius|title=XXI.?On the transformation-products of starch|journal=Journal of the Chemical Society|date=1872|volume=25|pages=579–588|doi=10.1039/JS8722500579|url=https://pubs.rsc.org/en/Content/ArticleLanding/1872/JS/js8722500579|access-date=11 December 2014}}</ref> Its name comes from [[malt]], combined with the suffix '[[-ose]]' which is used in names of sugars.<ref name=Stoker /><br />
<br />
== Structure and nomenclature ==<br />
Carbohydrates are generally divided into [[monosaccharide]]s, [[oligosaccharide]]s, and [[polysaccharide]]s depending on the number of sugar subunits. Maltose, with two sugar units, is a disaccharide, which falls under oligosaccharides. Glucose is a [[hexose]]: a monosaccharide containing six carbon atoms. The two glucose units are in the [[pyranose]] form and are joined by an [[glycosidic bond|O-glycosidic bond]], with the first carbon (C<sub>1</sub>) of the first [[glucose]] linked to the fourth carbon (C<sub>4</sub>) of the second [[glucose]], indicated as (1→4). The link is characterized as α because the glycosidic bond to the anomeric carbon (C<sub>1</sub>) is in the opposite plane from the {{chem|C|H|2|O|H}} [[substituent]] in the same ring (C<sub>6</sub> of the first glucose). If the glycosidic bond to the anomeric carbon (C<sub>1</sub>) were in the same plane as the {{chem|C|H|2|O|H}} substituent, it would be classified as a '''β(1→4)''' bond, and the resulting molecule would be [[cellobiose]]. The anomeric carbon (C<sub>1</sub>) of the second glucose molecule, which is not involved in a glycosidic bond, could be either an α- or β-anomer depending on the bond direction of the attached hydroxyl group relative to the {{chem|C|H|2|O|H}} substituent of the same ring, resulting in either α-maltose or β-maltose.{{Citation needed|date=January 2021}}<br />
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An [[isomer]] of maltose is [[isomaltose]]. This is similar to maltose but instead of a bond in the α(1→4) position, it is in the α(1→6) position, the same bond that is found at the branch points of [[glycogen]] and [[amylopectin]].{{Citation needed|date=January 2021}}<br />
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== Properties ==<br />
Like glucose, maltose is a [[reducing sugar]], because the ring of one of the two glucose units can open to present a free [[aldehyde]] group; the other one cannot because of the nature of the glycosidic bond. Maltose can be broken down to glucose by the [[maltase]] enzyme, which catalyses the hydrolysis of the glycosidic bond.{{Citation needed|date=January 2021}}<br />
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Maltose in aqueous solution exhibits [[mutarotation]], because the α and β isomers that are formed by the different conformations of the anomeric carbon have different [[specific rotation]]s, and in aqueous solutions, these two forms are in equilibrium. Maltose can easily be detected by the Woehlk test or Fearon's test on methylamine.<ref>{{Cite journal|url=http://www.chemistryviews.org/details/education/10821368/150_Years_Alfred_wohlk.html|title=150 Years Alfred Wöhlk :: Education|website=ChemistryViews|date=6 March 2018 |doi=10.1002/chemv.201800002|author-first1=Klaus|author-last1=Ruppersberg|author-first2=Janet|author-last2=Blankenburg|url-access=subscription}}</ref><br />
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It has a sweet taste, but is only about 30–60% as sweet as sugar, depending on the concentration.<ref>{{Cite book|url=https://books.google.com/books?id=xteiARU46SQC&pg=PA863|title=Food Chemistry|last1=Belitz|first1=H.-D.|last2=Grosch|first2=Werner|last3=Schieberle|first3=Peter|date=2009-01-15|publisher=Springer Science & Business Media|isbn=9783540699330|pages=863|language=en}}</ref> A 10% solution of maltose is 35% as sweet as sucrose.<ref>{{Cite book|url=https://books.google.com/books?id=db5QAwAAQBAJ&pg=PA271|title=Optimising Sweet Taste in Foods|last=Spillane|first=W. J.|date=2006-07-17|publisher=Woodhead Publishing|isbn=9781845691646|pages=271|language=en}}</ref><br />
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== Sources and absorption ==<br />
[[Image:Maltose syrup.jpg|thumb|right|Maltose syrup]]<br />
Maltose is a [[malt]] component, a substance obtained when the grain is softened in water and germinates. It is also present in highly variable quantities in partially hydrolyzed starch products like [[maltodextrin]], [[corn syrup]] and acid-thinned starch.<ref>{{Cite book|url=https://books.google.com/books?id=XcSp015g4X0C&pg=PA45|title=CRC Handbook of Food Additives, Second Edition|last=Furia|first=Thomas E.|date=1973-01-02|publisher=CRC Press|isbn=9780849305429|language=en}}</ref><br />
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Outside of plants, maltose is also (likely) found in [[sugarbag|honey]].<ref>{{Cite book |last=Heard |first=Tim |date=2015-10-30 |title=The Australian Native Bee Book|publisher=Sugarbag Bees|isbn=9780646939971|language=en}}</ref><br />
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In humans, maltose is broken down by various maltase enzymes, providing two glucose molecules that can be [[Glucose metabolism|further processed]]: either broken down to provide energy, or stored as glycogen. The lack of the [[sucrase-isomaltase]] enzyme in humans causes [[sucrose intolerance]], but complete maltose intolerance is extremely rare because there are four different maltase enzymes.<ref>{{Cite book|url=https://books.google.com/books?id=whILjP8XUS4C&pg=PA60|title=Control of Glycogen Metabolism|last1=Whelan|first1=W. J.|last2=Cameron|first2=Margaret P.|date=2009-09-16|publisher=John Wiley & Sons|isbn=9780470716885|pages=60|language=en}}</ref><br />
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== References ==<br />
{{Reflist}}<br />
<br />
==External links==<br />
*{{Commons category-inline}}<br />
*[https://web.archive.org/web/20051124215824/http://www.elmhurst.edu/~chm/vchembook/546maltose.html Maltose], Elmhurst College Virtual Chembook.<br />
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{{Carbohydrates}}<br />
{{Sugar}}<br />
{{Authority control}}<br />
<br />
[[Category:Disaccharides]]<br />
[[Category:Starch]]<br />
[[Category:Types of sugar]]<br />
[[Category:Malt]]</div>2405:4802:1CAA:EE20:85A3:CD57:ADBD:3944https://wiki.sarg.dev/index.php?title=Lactose&diff=12003Lactose2025-10-27T17:07:47Z<p>2405:4802:1CAA:EE20:85A3:CD57:ADBD:3944: </p>
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<div>{{short description|Carbohydrate}}<br />
{{Chembox<br />
| Verifiedfields = changed<br />
| Watchedfields = changed<br />
| verifiedrevid = 477497006<br />
| Name = Lactose<br />
| ImageFile_Ref = {{chemboximage|correct|??}}<br />
| ImageFile = Beta-D-Lactose.svg<br />
| ImageSize = 200px<br />
| ImageClass = skin-invert-image<br />
| IUPACName = β-{{sm|d}}-Galactopyranosyl-(1→4)-α-{{sm|d}}-glucopyranose<br><br />
4-''O''-β-{{sm|d}}-Galactopyranosyl-α-{{sm|d}}-glucopyranose<br />
| SystematicName = (2''R'',3''R'',4''S'',5''R'',6''S'')-2-(Hydroxymethyl)-6-<nowiki/>{[(2''R'',3''S'',4''R'',5''R'',6''R'')-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxy}oxane-3,4,5-triol<br />
| OtherNames = Milk sugar<br />Lactobiose<br />4-''O''-β-<small>D</small>-Galactopyranosyl-<small>D</small>-glucose<br />
| Section1 = {{Chembox Identifiers<br />
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}<br />
| ChemSpiderID = 5904<br />
| 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<br />
| InChIKey = GUBGYTABKSRVRQ-DCSYEGIMBP<br />
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}<br />
| StdInChI = 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<br />
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}<br />
| StdInChIKey = GUBGYTABKSRVRQ-DCSYEGIMSA-N<br />
| CASNo = 63-42-3<br />
| CASNo_Ref = {{cascite|correct|CAS}}<br />
| EC_number = 200-559-2<br />
| KEGG = C01970<br />
| PubChem = 6134<br />
| ChEMBL_Ref = {{ebicite|correct|EBI}}<br />
| ChEMBL = 417016<br />
| Gmelin = 342369<br />
| Beilstein = 90841<br />
| UNII_Ref = {{fdacite|correct|FDA}}<br />
| UNII = 3SY5LH9PMK<br />
| ChEBI_Ref = {{ebicite|correct|EBI}}<br />
| ChEBI = 36218<br />
| 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<br />
}}<br />
| Section2 = {{Chembox Properties<br />
| C=12 | H=22 | O=11<br />
| Appearance = White solid<br />
| Density = 1.525{{nbsp}}g/cm<sup>3</sup><br />
| 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"/><br />
| MeltingPt_ref =<br />
| 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 [[ethanol]] 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}}.<br />
ds</ref><br />
| SpecRotation = +55.4° (anhydrous)<br />+52.3° (monohydrate)<br />
}}<br />
| Section4 = {{Chembox Thermochemistry| DeltaHc = 5652{{nbsp}}kJ/mol, 1351{{nbsp}}kcal/mol, 16.5{{nbsp}}kJ/g, 3.94{{nbsp}}kcal/g}}<br />
| Section7 = {{Chembox Hazards<br />
| FlashPtC = 357.8<br />
| FlashPt_ref = <ref name=Ald>[http://www.sigmaaldrich.com/catalog/product/sial/17814?lang=en&region=US Sigma Aldrich]</ref><br />
| AutoignitionPtC =<br />
| NFPA-H = 0<br />
| NFPA-F = 0<br />
| NFPA-R = 0<br />
}}<br />
}}<br />
<br />
'''Lactose''' is a [[disaccharide]] composed of [[galactose]] and [[glucose]] and has the [[molecular formula]] C<sub>12</sub>H<sub>22</sub>O<sub>11</sub>. Lactose makes up around 2–8% of [[milk]] (by mass). The name comes from {{wikt-lang|la|lac}} ([[Genitive case|gen]].&nbsp;{{wikt-lang|la|lactis}}), the [[Latin]] word for milk, plus the suffix ''[[-ose]]'' used to name sugars. The compound is a white, [[water-soluble]], non-[[Hygroscopy|hygroscopic]] 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><br />
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==Structure and reactions==<br />
[[File:Alpha-lactose-from-xtal-3D-balls.png|thumb|left|The molecular structure of α-lactose, as determined by [[X-ray crystallography]].]]<br />
Lactose is a [[disaccharide]] composed of [[galactose]] and [[glucose]], which form a β-1→4 [[Glycosidic bond|glycosidic]] linkage. Its [[systematic name]] is β-<small>D</small>-galactopyranosyl-(1→4)-<small>D</small>-glucose. The glucose can be in either the α-[[pyranose]] 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 [[anomer]]ic form of the glucopyranose ring alone. Detection reactions for lactose are the [[Alfred Wöhlk|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|url-access=subscription }}</ref> and [[William Fearon|Fearon]] tests.<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 |bibcode=1942Ana....67..130F |issn=0003-2654|url-access=subscription }}</ref> They can be used to detect the different lactose content of [[dairy products]] such as [[whole milk]], [[Lactose free diet|lactose free milk]], [[yogurt]], [[buttermilk]], [[coffee creamer]], [[sour cream]], [[kefir]], 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=[[Chemistry Teacher International]] |volume=2 |issue=2 |doi=10.1515/cti-2019-0008 |issn=2569-3263 |s2cid=208714341 |doi-access=free}}</ref><br />
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Lactose is [[hydrolysed]] to glucose and galactose, [[isomerisation|isomerised]] in [[Basicity|alkaline]] solution to [[lactulose]], and [[catalysis|catalytically]] [[Hydrogenation|hydrogenated]] to the corresponding [[polyhydric alcohol]], [[lactitol]].<ref name="Linko1981"/> Lactulose is a commercial product, used for treatment of [[constipation]].<ref>{{Citation |last=Hawrelak |first=Jason A. |title=104 - Prebiotics, Synbiotics, and Colonic Foods |date=2020-01-01 |work=Textbook of Natural Medicine (Fifth Edition) |pages=797–808.e4 |editor-last=Pizzorno |editor-first=Joseph E. |url=https://linkinghub.elsevier.com/retrieve/pii/B9780323430449001047 |access-date=2025-02-15 |place=St. Louis (MO) |publisher=Churchill Livingstone |doi=10.1016/b978-0-323-43044-9.00104-7 |isbn=978-0-323-52342-4 |editor2-last=Murray |editor2-first=Michael T.|url-access=subscription }}</ref><br />
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==Occurrence and isolation==<br />
Lactose comprises about 2–8% of milk by weight. Several million tons are produced annually as a by-product of the [[dairy industry]].{{cn|date=May 2024}}<br />
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[[Whey]] or milk plasma is the liquid remaining after milk is curdled and strained, for example in the production of [[cheese]]. 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 [[protein]]s. The protein fraction is used in [[infant nutrition]] and [[sports nutrition]] 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=[[Journal of Food Science]] |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 [[ethanol]].<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><br />
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==Metabolism==<br />
{{See also|Lactose intolerance|Lactase persistence}}<br />
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Infant [[mammal]]s nurse on their mothers to drink milk, which is rich in lactose. The [[Intestinal villus|intestinal villi]] secrete the [[enzyme]] [[lactase]] (β-D-galactosidase) to digest it. This enzyme cleaves the lactose molecule into its two subunits, the simple [[sugar]]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.<ref>{{Citation |last1=Balaresque |first1=P. |title=Chapter Nine - Human Phenotypic Diversity: An Evolutionary Perspective |date=2016-01-01 |journal=Current Topics in Developmental Biology |volume=119 |pages=349–390 |editor-last=Orgogozo |editor-first=Virginie |url=https://linkinghub.elsevier.com/retrieve/pii/S0070215316300011 |access-date=2025-02-15 |series=Genes and Evolution |publisher=Academic Press |doi=10.1016/bs.ctdb.2016.02.001 |last2=King |first2=T. E.|pmid=27282030 |url-access=subscription }}</ref><ref>{{Cite journal |last1=Gerbault |first1=Pascale |last2=Liebert |first2=Anke |last3=Itan |first3=Yuval |last4=Powell |first4=Adam |last5=Currat |first5=Mathias |last6=Burger |first6=Joachim |last7=Swallow |first7=Dallas M. |last8=Thomas |first8=Mark G. |date=2011-03-27 |title=Evolution of lactase persistence: an example of human niche construction |journal=Philosophical Transactions of the Royal Society B: Biological Sciences |language=en |volume=366 |issue=1566 |pages=863–877 |doi=10.1098/rstb.2010.0268 |issn=0962-8436 |pmc=3048992 |pmid=21320900}}</ref><br />
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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 due to selection for genes that continue lactase production. In many of these areas, milk from mammals such as [[cattle]], [[goats]], and [[sheep]] is used as a large source of food. It was in these regions that genes for lifelong lactase production first [[evolution|evolved]].<ref>{{Cite journal |last1=Itan |first1=Yuval |last2=Powell |first2=Adam |last3=Beaumont |first3=Mark A. |last4=Burger |first4=Joachim |last5=Thomas |first5=Mark G. |date=2009-08-28 |editor-last=Tanaka |editor-first=Mark M. |title=The Origins of Lactase Persistence in Europe |journal=PLOS Computational Biology |language=en |volume=5 |issue=8 |article-number=e1000491 |doi=10.1371/journal.pcbi.1000491 |doi-access=free |issn=1553-7358 |pmc=2722739 |pmid=19714206|bibcode=2009PLSCB...5E0491I }}</ref> 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= [[HarperCollins]] |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 [[gut flora]], which can lead to diarrhea, bloating, flatulence, and other gastrointestinal symptoms.<br />
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==Biological properties==<br />
The [[sweetness]] of lactose is 0.2 to 0.4, relative to 1.0 for [[sucrose]].<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 [[fructose]] is 1.3, of galactose is 0.5 to 0.7, of [[maltose]] is 0.4 to 0.5, of [[sorbose]] is 0.4, and of [[xylose]] is 0.6 to 0.7.<ref name="Schaafsma2008" /><br />
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When lactose is completely digested in the [[small intestine]], its [[caloric value]] is 4 kcal/g, or the same as that of other [[carbohydrate]]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 [[intestine]]s, the caloric value of lactose ranges from 2 to 4 kcal/g.<ref name="Schaafsma2008" /> Undigested lactose acts as [[dietary fiber]]. It also has positive effects on absorption of [[mineral]]s, such as [[calcium]] and [[magnesium]].<ref name="Schaafsma2008" /><br />
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The [[glycemic index]] 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" /><br />
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Lactose has relatively low [[cariogenicity]] 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 [[dental plaque]] formation and it is not rapidly [[fermentation|fermented]] by [[mouth|oral]] [[bacteria]].<ref name="MillerJarvis2006" /> The buffering capacity of milk also reduces the cariogenicity of lactose.<ref name="Schaafsma2008" /><br />
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==Applications==<br />
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 commonly added directly to food, because its low solubility can lead to a gritty mouthfeel.<ref>{{Cite journal |last1=Dominici |first1=Simona |last2=Marescotti |first2=Francesca |last3=Sanmartin |first3=Chiara |last4=Macaluso |first4=Monica |last5=Taglieri |first5=Isabella |last6=Venturi |first6=Francesca |last7=Zinnai |first7=Angela |last8=Facioni |first8=Maria Sole |date=2022-05-19 |title=Lactose: Characteristics, Food and Drug-Related Applications, and Its Possible Substitutions in Meeting the Needs of People with Lactose Intolerance |journal=Foods |language=en |volume=11 |issue=10 |page=1486 |doi=10.3390/foods11101486 |doi-access=free |issn=2304-8158 |pmc=9141425 |pmid=35627056}}</ref> [[Infant formula]] is a notable exception, where lactose is added to match the composition of human milk.<ref>{{Cite journal |last1=Slupsky |first1=Carolyn M. |last2=He |first2=Xuan |last3=Hernell |first3=Olle |last4=Andersson |first4=Yvonne |last5=Rudolph |first5=Colin |last6=Lönnerdal |first6=Bo |last7=West |first7=Christina E. |date=2017-06-16 |title=Postprandial metabolic response of breast-fed infants and infants fed lactose-free vs regular infant formula: A randomized controlled trial |journal=Scientific Reports |language=en |volume=7 |issue=1 |page=3640 |doi=10.1038/s41598-017-03975-4 |issn=2045-2322 |pmc=5473881 |pmid=28623320|bibcode=2017NatSR...7.3640S }}</ref> However, lactose-reduced formulas are increasing in popularity.<ref>{{Cite journal |last1=DiMaggio |first1=Dina M. |last2=Abersone |first2=Ilze |last3=Porto |first3=Anthony F. |date=2024 |title=Infant consumption of 100% lactose-based and reduced lactose infant formula in the United States: Review of NHANES data from 1999 to 2020 |url=https://onlinelibrary.wiley.com/doi/10.1002/jpn3.12292 |journal=Journal of Pediatric Gastroenterology and Nutrition |language=en |volume=79 |issue=5 |pages=1017–1023 |doi=10.1002/jpn3.12292 |pmid=38934419 |issn=1536-4801|url-access=subscription }}</ref><br />
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One of the undesirable properties of lactose utilization is its low solubility, which can result in crystallization, giving a gritty and sandy mouthfeel in the final product. Usually, in supersaturated solution, sugars tend to crystallize, also forming big agglomerates, depending on the process condition.<br />
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Lactose is not fermented by most [[yeast]] 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 [[milk stout]] or a cream stout.<br />
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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.<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 |archive-url=https://web.archive.org/web/20150224064134/http://www.rd.usda.gov/files/RR214.pdf |archive-date=February 24, 2015 |publisher=United States Department of Agriculture Rural Development}}.</ref><br />
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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 [[atorvastatin]], [[levocetirizine]] or [[thiamazole]] among many others).<ref name=Ull/><ref>{{Cite journal |last1=Zdrojewicz |first1=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><br />
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==History==<br />
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}}'' ... [Procedure for asthma ... ], (Bologna ("Bononia"), (Italy): Nicolò Tebaldini for the heirs of Evangelista Dozza, 1633), [https://books.google.com/books?id=T3JEAAAAcAAJ&pg=PA399 p. 400.] 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. [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.)<br /><br />
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, [http://digital.slub-dresden.de/werkansicht/dlf/79899/913/1/cache.off page 163.] {{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. [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: ... )</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, [https://books.google.com/books?id=hwM9AAAAcAAJ&pg=PP9 ''De novo Saccharo Lactis''] [On the new milk sugar] (Venice, (Italy): Hertz, 1700).</ref> In 1715, Testi's procedure for making milk sugar was published by Antonio Vallisneri.<ref>Ludovico Testi (1715) [http://babel.hathitrust.org/cgi/pt?view=image;size=100;id=ucm.5324347611;page=root;seq=93;num=69 "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.</ref> Lactose was identified as a sugar in 1780 by [[Carl Wilhelm Scheele]].<ref>See:<br />
* Carl Wilhelm Scheele (1780) [https://books.google.com/books?id=9N84AAAAMAAJ&pg=PA116 "Om Mjölk och dess syra"] (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, ... )<br />
* Carl Wilhelm Scheele (1780) [https://books.google.com/books?id=9N84AAAAMAAJ&pg=PA269 "Om Mjölk-Såcker-Syra"] (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><br />
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In 1812, Heinrich Vogel (1778–1867) recognized that glucose was a product of hydrolyzing lactose.<ref>See:<br />
* Vogel (1812) [http://babel.hathitrust.org/cgi/pt?id=nyp.33433062722768;view=1up;seq=492 "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.<br />
* H. A. Vogel (1812) [https://books.google.com/books?id=yKuZAAAAIAAJ&pg=PA125 "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.</ref> In 1856, [[Louis Pasteur]] crystallized the other component of lactose, galactose.<ref>Pasteur (1856) [https://archive.org/stream/ComptesRendusAcademieDesSciences0042/ComptesRendusAcadmieDesSciences-Tome042-Janvier-juin1856#page/n350/mode/1up "Note sur le sucre de lait"] (Note on milk sugar), ''Comptes rendus'', '''42''' : 347–351.</ref> By 1894, [[Emil Fischer]] had established the configurations of the component sugars.<ref>Fischer determined the configuration of glucose in:<br />
* Emil Fischer (1891) [http://gallica.bnf.fr/ark:/12148/bpt6k90723d/f1838.image.langEN "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.<br />
* 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.<br />
Fischer established the configuration of galactose in:<br />
* Emil Fischer and Robert S. Morrell (1894) [http://gallica.bnf.fr/ark:/12148/bpt6k90732c/f403.image.langEN "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.</ref><br />
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Lactose was named by the French chemist [[Jean-Baptiste Dumas|Jean Baptiste André Dumas]] (1800–1884) in 1843.<ref>Dumas, ''Traité de Chimie, Appliquée aux Arts'', volume 6 (Paris, France: Bechet Jeune, 1843), [https://books.google.com/books?id=zQTyoAqqQzYC&pg=PA293 p. 293.]</ref> In 1856, Pasteur named galactose "lactose".<ref>Pasteur (1856) [https://archive.org/stream/ComptesRendusAcademieDesSciences0042/ComptesRendusAcadmieDesSciences-Tome042-Janvier-juin1856#page/n350/mode/1up "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''.)</ref> In 1860, [[Marcellin Berthelot]] renamed it "galactose", and transferred the name "lactose" to what is now called lactose.<ref>Marcellin Berthelot, ''Chimie organique fondée sur la synthèse'' [Organic chemistry based on synthesis] (Paris, France: Mallet-Bachelier, 1860), vol. 2, [https://books.google.com/books?id=7AtQYV5FlVwC&pg=PA248 pp. 248–249] and [https://books.google.com/books?id=7AtQYV5FlVwC&pg=PA268 pp. 268–270.]</ref> It has a formula of {{chem2|C12H22O11}} and the hydrate formula {{chem2|C12H22O11·H2O}}, making it an [[isomer]] of sucrose.<br />
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==See also==<br />
* [[Lac operon]]<br />
* [[Lactic acid]]<br />
* [[Lactose intolerance]]<br />
* [[Nectar]]<br />
* [[Sugars in wine]]<br />
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==References==<br />
{{Reflist}}<br />
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==External links==<br />
* {{Commons category-inline}}<br />
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{{Carbohydrates}}<br />
{{Sugar}}<br />
{{Authority control}}<br />
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[[Category:Lactose| ]]<br />
[[Category:1633 introductions]]<br />
[[Category:Disaccharides]]<br />
[[Category:Excipients]]<br />
[[Category:Types of sugar]]</div>2405:4802:1CAA:EE20:85A3:CD57:ADBD:3944