Editing Vanillin (section)

===Natural production===
Natural vanillin is extracted from the seed pods of ''[[Vanilla planifolia]]'', a [[vine|vining]] [[orchid]] native to Mexico, but now grown in tropical areas around the globe.  [[Madagascar]] is presently the largest producer of natural vanillin.

[[File:Glucovanillin_v2.svg|200px|thumb|right|[[Glucovanillin]], the β-{{sc|D}}-glucoside of vanillin]]
As harvested, the green seed pods contain vanillin in the form of [[glucovanillin]], its β-{{sc|D}}-[[glucoside]]; the green pods do not have the flavor or odor of vanilla.<ref name = walton>[[#walton2003|Walton 2003]].</ref>  Vanillin is released from glucovanillin by the action of the enzyme [[β-glucosidase]] during ripening<ref>{{cite journal | doi = 10.1111/j.1365-2621.1943.tb18011.x | title = ACTION OF a β-GLUCOSIDASE IX THE CURING OF VANILLA | date = 1943 | last1 = Arana | first1 = Francisca E. | journal = Journal of Food Science | volume = 8 | issue = 4 | pages = 343–351 }}</ref><ref>{{cite journal | title = Changes in vanillin and glucovanillin concentrations during the various stages of the process traditionally used for curing Vanilla fragrans beans in Reunion | author = Odoux, Eric | date = 2000 | journal = Fruits | volume = 55 | issue = 2 | pages = 119–125 }}</ref> and during the curing process.<ref>{{cite journal | doi = 10.1021/jf00058a019 | title = Determination of Glucovanillin and Vanillin in Cured Vanilla Pods | date = 1995 | last1 = Voisine | first1 = Richard | last2 = Carmichael | first2 = Lucie | last3 = Chalier | first3 = Pascale | last4 = Cormier | first4 = Francois | last5 = Morin | first5 = Andre | journal = Journal of Agricultural and Food Chemistry | volume = 43 | issue = 10 | pages = 2658–2661 | bibcode = 1995JAFC...43.2658V }}</ref>

After being harvested, their flavor is developed by a months-long curing process, the details of which vary among vanilla-producing regions, but in broad terms it proceeds as follows:

First, the seed pods are [[blanching (cooking)|blanched]] in hot water, to arrest the processes of the living plant tissues.  Then, for 1–2 weeks, the pods are alternately sunned and sweated: during the day they are laid out in the sun, and each night wrapped in cloth and packed in airtight boxes to sweat.  During this process, the pods become dark brown, and [[enzyme]]s in the pod release vanillin as the free molecule.  Finally, the pods are dried and further aged for several months, during which time their flavors further develop.  Several methods have been described for curing vanilla in days rather than months, although they have not been widely developed in the natural vanilla industry,{{efn|[[#dignum2001|Dignum 2001]] reviews several such proposed innovations in vanilla processing, including processes in which the seed pods are chopped, frozen, warmed by a heat source other than the sun, or crushed and treated by various enzymes.  Whether or not these procedures produce a product whose taste is comparable to traditionally prepared natural vanilla, many of them are incompatible with the customs of the natural vanilla market, in which the vanilla beans are sold whole, and graded by, among other factors, their length.}} with its focus on producing a premium product by established methods, rather than on innovations that might alter the product's flavor profile.

====Biosynthesis====

[[File:Vanillin Biosynthesis.gif|thumb|Some of the proposed routes of vanillin biosynthesis]]

Although the exact route of vanillin biosynthesis in ''V.&nbsp;planifolia'' is currently unknown, several pathways are proposed for its biosynthesis. Vanillin biosynthesis is generally agreed to be part of the [[phenylpropanoid pathway]] starting with {{sc|L}}-phenylalanine,<ref name="digital.library.unt.edu">{{cite journal | last1 = Dixon | first1 = R.&nbsp;A. | title = Vanillin Biosynthesis – Not as simple as it seems? | url = https://digital.library.unt.edu/ark:/67531/metadc279692/m2/1/high_res_d/Dixon%20vanillin%202011.pdf | journal = Handbook of Vanilla Science and Technology | year = 2014  | page = 292 }}</ref> which is deaminated by [[phenylalanine ammonia lyase]] (PAL) to form t-[[cinnamic acid]]. The [[Arene substitution pattern|''para'']] position of the ring is then [[hydroxylate]]d by the [[cytochrome P450]] enzyme cinnamate 4-hydroxylase (C4H/P450) to create ''p''-[[coumaric acid]].<ref name="nature.com">{{cite journal | last1 = Gallage | first1 = N.&nbsp;J. | last2 = Hansen | first2 = E.&nbsp;H. | last3 = Kannangara | first3 = R. | last4 = Olsen | first4 = E.&nbsp;C. | last5 = Motawia | first5 = M.&nbsp;S. | last6 = Jørgensen | first6 = K. | last7 = Holme | first7 = I. | last8 = Hebelstrup | first8 = K. | last9 = Grisoni | first9 = M. | last10 = Møller | first10 = L.&nbsp;B. | title = Vanillin formation from ferulic acid in ''Vanilla planifolia'' is catalysed by a single enzyme | journal = Nature Communications | year = 2014 | volume = 5 | page = 4037 | doi = 10.1038/ncomms5037 | pmid=24941968 | pmc=4083428| bibcode = 2014NatCo...5.4037G }}</ref> Then, in the proposed ferulate pathway, 4-hydroxycinnamoyl-CoA ligase (4CL) attaches ''p''-coumaric acid to [[coenzyme A]] (CoA) to create ''p''-coumaroyl CoA. [[Hydroxycinnamoyl transferase]] (HCT) then converts ''p''-coumaroyl CoA to 4-coumaroyl [[shikimate]]/[[quinate]]. This subsequently undergoes oxidation by the P450 enzyme coumaroyl ester 3’-hydroxylase (C3’H/P450) to give caffeoyl shikimate/quinate. HCT then exchanges the shikimate/quinate for CoA to create caffeoyl CoA, and 4CL removes CoA to afford caffeic acid. Caffeic acid then undergoes [[methylation]] by caffeic acid O-[[methyltransferase]] (COMT) to give ferulic acid. Finally, vanillin synthase hydratase/lyase (vp/VAN) catalyzes hydration of the double bond in ferulic acid followed by a retro-aldol elimination to afford vanillin.<ref name="nature.com"/> Vanillin can also be produced from vanilla glycoside with the additional final step of deglycosylation.<ref name = walton/> In the past ''p''-hydroxybenzaldehyde was speculated to be a precursor for vanillin biosynthesis. However, a 2014 study using [[radiolabelled]] [[precursor (chemistry)|precursor]] indicated that ''p''-hydroxybenzaldehyde is not used to synthesise vanillin or vanillin glucoside in the vanilla orchids.<ref name="nature.com" />