Editing Lactose (section)

==Structure and reactions==
[[File:Alpha-lactose-from-xtal-3D-balls.png|thumb|left|The molecular structure of α-lactose, as determined by [[X-ray crystallography]].]]
[[File:Lactose.jpg|left|thumb|Lactose crystals, viewed under [[polarized light]]]]
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 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 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 |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>

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>