Lactose
18643
220743181
2008-06-21T10:48:00Z
Elbreapoly
6697096
Reverted my "drugbox" conversion back to "chembox". I could not change the coding of the "drugbox" to omit drug-only parameters as hoped, thus coded a new chembox.
{{Chembox new
| Name = Lactose
| ImageFile = lactose3.png
| IUPACName = (2''S'',3''R'',4''R'',5''S'',6''R'')-6- (hydroxymethyl)-5-((2''S'',3''R'',4''S'',5''R'',6''R'')- 3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro- 2''H''-pyran-2-yloxy)tetrahydro-2''H''-pyran-2,3,4-triol
| OtherNames = Milk Sugar
| Section1 = {{Chembox Identifiers
| SMILES =
| CASNo = 63-42-3
}}
| Section2 = {{Chembox Properties
| Formula = C<sub>12</sub>H<sub>22</sub>O<sub>11</sub>
| MolarMass = 342.29648 g/mol
| Appearance = white solid
| Density =
| Solubility = 0.216 g/mL
| MeltingPt =
}}
}}
'''Lactose''' (also referred to as ''milk sugar'') is a [[sugar]] which is found most notably in [[milk]]. Lactose makes up around 2–8% of milk (by weight). The name comes from the [[Latin]] word for milk, plus the -ose ending used to name sugars. Its systematic name is β-D-galactopyranosyl-(1↔4)β-D-glucopyranose.
==Chemistry==
Lactose is a [[disaccharide]] that consists of β-D-[[galactose]] and β-D-[[glucose]] fragments bonded through a β1-4 [[glycosidic]] linkage.
===Solubility===
Lactose has a solubility of 1 in 4.63 measured %w/v. This translates to 0.216 g of lactose dissolving readily in 1 mL of water.
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.<ref name="path">{{cite journal
| year = 2000
| last = Machado
| first = José J.B.
| coauthors = João A. Coutinho, Eugénia A. Macedo
| url = http://path.web.ua.pt/file/FPE%20(2000)%20173%20121.pdf
| title = Solid–liquid equilibrium of a-lactose in ethanol/water
| format = PDF
| publisher = Fluid Phase Equilibria
| accessdate = 2007-12-05
}}</ref>
==Digestion of lactose==
{{Main|Lactose intolerance}}
Infant [[mammal]]s are fed on milk by their mothers. To digest it an [[enzyme]] called [[lactase]] (β-D-galactosidase) is secreted by the intestinal [[Intestinal villus|villi]], and this enzyme cleaves the molecule into its two subunits [[glucose]] and [[galactose]] for absorption.
Since lactose occurs mostly in milk, in most mammals the production of lactase gradually decreases with maturity.
Many people with ancestry in [[Europe]], the [[Middle East]], [[India]], or parts of [[East Africa]], maintain normal lactase production into adulthood. In many of these cultures, mammals such as [[cattle]], [[goats]], and [[sheep]] are milked for food. Hence, it was in these regions that genes for lifelong lactase production first [[evolution|evolved]]. The genes of lactose tolerance have evolved independently in various ethnic groups. <ref name="NYT">
People who are not tolerant may suffer certain socially unacceptable symptoms of too much lactose consumption. basically, lactose is not broken down and provides food for gas producing gut flora. This leads to bloating, and flatulence and perhaps GI upset.
{{cite news
| author= Nicholas Wade
| title= Study Detects Recent Instance of Human Evolution
| date= [[December 10]], [[2006]]
| publisher= ''[[The New York Times]]''
| url= http://www.nytimes.com/2006/12/10/science/10cnd-evolve.html?
| accessdate= 2007-12-05
}}</ref>
==References==
{{reflist}}
{{Carbohydrates}}
[[Category:Disaccharides]]
[[Category:Sweeteners]]
[[ar:لاكتوز]]
[[bg:Лактоза]]
[[ca:Lactosa]]
[[cs:Laktóza]]
[[cy:Lactos]]
[[da:Laktose]]
[[de:Milchzucker]]
[[es:Lactosa]]
[[eo:Laktozo]]
[[eu:Laktosa]]
[[fr:Lactose]]
[[is:Laktósi]]
[[it:Lattosio]]
[[he:לקטוז]]
[[la:Lactosium]]
[[lt:Laktozė]]
[[hu:Laktóz]]
[[mk:Лактоза]]
[[ms:Laktosa]]
[[nl:Lactose]]
[[ja:ラクトース]]
[[no:Laktose]]
[[nn:Laktose]]
[[oc:Lactòsa]]
[[pl:Laktoza]]
[[pt:Lactose]]
[[ru:Лактоза]]
[[sq:Laktoza]]
[[simple:Lactose]]
[[sl:Laktoza]]
[[sr:Лактоза]]
[[sh:Laktoza]]
[[fi:Laktoosi]]
[[sv:Laktos]]
[[tr:Laktoz]]
[[uk:Лактоза]]
[[zh:乳糖]]