View source for Vanillin

{{Chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 456486843
| ImageFileL1 = Vanillin v3.svg
| ImageClassL1 = skin-invert 
| ImageSizeL1 = 100px
| ImageFileL1_Ref = {{chemboximage|correct|??}}
| ImageNameL1 = Skeletal formula of vanillin 
| ImageFileR1 = Vanillin-3d.png
| ImageClassR1 = bg-transparent  
| ImageSizeR1 = 150px
| ImageFileR1_Ref = {{chemboximage|correct|??}}
| ImageNameR1 = Spacefill model of vanillin 
| ImageFile2 = Vanlilin vzorek.jpg
| PIN = 4-Hydroxy-3-methoxybenzaldehyde
| OtherNames = Vanillin<ref name=Vanillin>{{cite web|url = http://sci-toys.com/ingredients/vanillin.html |title = Vanillin|first = Simon Quellen|last =Field|website = sci-toys.com}}</ref><br />Methyl vanillin<ref name=Vanillin/><br />Vanillic aldehyde<ref name=PubChem>{{PubChem|1183}}.</ref>
|Section1={{Chembox Identifiers
| IUPHAR_ligand = 6412
| CASNo = 121-33-5
| CASNo_Ref = {{cascite|correct|CAS}}
| PubChem = 1183
| ChemSpiderID = 13860434
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| UNII = CHI530446X
| UNII_Ref = {{fdacite|correct|FDA}}
| EINECS = 204-465-2
| KEGG = D00091
| KEGG_Ref = {{keggcite|correct|kegg}}
| MeSHName = vanillin
| ChEBI = 18346
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEMBL = 13883
| ChEMBL_Ref = {{ebicite|correct|EBI}}
| RTECS = YW5775000
| Beilstein = 472792
| Gmelin = 3596
| 3DMet = B00167
| SMILES = c1(C=O)cc(OC)c(O)cc1
| StdInChI = 1S/C8H8O3/c1-11-8-4-6(5-9)2-3-7(8)10/h2-5,8H,1H3
| StdInChI_Ref = {{stdinchicite|changed|chemspider}}
| InChI = 1/C8H8O3/c1-11-8-4-6(5-9)2-3-7(8)10/h2-5,10H,1H3
| StdInChIKey = MWOOGOJBHIARFG-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}}
| InChIKey = MWOOGOJBHIARFG-UHFFFAOYAS
}}
|Section2={{Chembox Properties
| C=8 | H=8 | O=3 
| Appearance = White solid
| Odor = Vanilla, sweet, balsamic, pleasant
| Density = 1.056 g/cm<sup>3</sup><ref name=crc1>{{cite book | editor= Haynes, William M. | date = 2016| title = [[CRC Handbook of Chemistry and Physics]] | edition = 97th | publisher = [[CRC Press]] | isbn = 978-1-4987-5429-3|page=3.310}}</ref>
| MeltingPtC = 81
| BoilingPtC = 285
| MeltingPt_ref=<ref name=crc1/>
| BoilingPt_ref=<ref name=crc1/>
| Solubility = 10 g/L
| LogP = 1.208
| VaporPressure = >1 Pa
| pKa = 7.781
| pKb = 6.216
}}
|Section3={{Chembox Structure
| CrystalStruct = Monoclinic
}}
|Section4={{Chembox Thermochemistry
| DeltaHc = −3.828 MJ/mol
}}
|Section5={{Chembox Hazards
| ExternalSDS = [https://www.inchem.org/documents/icsc/icsc/eics1740.htm ICSC 1740]
| GHSPictograms = {{GHS exclamation mark}}
| GHSSignalWord = '''WARNING'''
| HPhrases = {{H-phrases|302|317|319}}
| PPhrases = {{P-phrases|280|305+351+338}}
| NFPA-F = 1
| NFPA-H = 1
| NFPA-R = 0
| FlashPtC = 147
}}
|Section6={{Chembox Related
| OtherCompounds = [[Anisaldehyde]]<br/>[[Apocynin]]<br/>[[Eugenol]]<br/>[[Phenol]]<br/>[[Vanillyl alcohol]]
}}
}}

'''Vanillin''' is an [[organic compound]] with the molecular formula {{chem2|auto=1|C8H8O3}}.  It is a [[phenolic aldehyde]].  Its [[functional groups]] include [[aldehyde]], [[hydroxyl]], and [[ether]].  It is the primary component of the ethanolic extract of the [[vanilla bean]].  Synthetic vanillin is now used more often than natural vanilla extract as a [[flavoring]] in foods, beverages, and pharmaceuticals.

Vanillin and [[ethylvanillin]] are used by the food industry;  ethylvanillin is more expensive, but has a stronger [[Note (perfumery)|note]]. It differs from vanillin by having an ethoxy group (−O−CH<sub>2</sub>CH<sub>3</sub>) instead of a methoxy group (−O−CH<sub>3</sub>).

Natural [[vanilla extract]] is a mixture of several hundred different compounds in addition to vanillin.  Artificial vanilla flavoring is often an ethanol solution of pure vanillin, usually of synthetic origin. Because of the scarcity and expense of natural vanilla,  synthetic preparation of artificial vanilla flavoring has long been of interest.  The first commercial synthesis of vanillin began with the more readily available natural compound [[eugenol]] (4-allyl-2-methoxyphenol).  Today, artificial vanillin is made either from [[guaiacol]] or [[lignin]].

Lignin-based artificial vanilla flavoring is alleged to have a richer flavor profile than that from guaiacol-based artificial vanilla; the difference is due to the presence of [[acetovanillone]], a minor component in the lignin-derived product that is not found in vanillin synthesized from guaiacol.{{efn|name=lig-vanillone|According to [[#esposito1997|Esposito 1997]], blind taste-testing panels cannot distinguish between the flavors of synthetic vanillin from lignin and those from guaicol, but can distinguish the odors of these two types of synthetic vanilla extracts.  Guaiacol vanillin, adulterated with acetovanillone, has an odor indistinguishable from lignin vanillin.}}

== Natural history ==
Although it is generally accepted that vanilla was domesticated in [[Mesoamerica]] and subsequently spread to the [[Old World]] in the 16th century, in 2019, researchers published a [[Academic paper|paper]] stating that vanillin residue had been discovered inside jars within a tomb in [[Palestine]] dating to the 2nd millennium BCE, suggesting the possible cultivation of an unidentified, Old World-endemic ''[[Vanilla (genus)|Vanilla]]'' species in [[Canaan]] since the Middle [[Bronze Age]].<ref>{{Cite journal | url=https://www.sciencedirect.com/science/article/abs/pii/S2352409X18307557 | title=First evidence for vanillin in the old world: Its use as mortuary offering in Middle Bronze Canaan | journal=Journal of Archaeological Science: Reports | date=June 2019 | last1 = Linares | first1 = V. | last2 = Adams | first2 = M.&nbsp;J. | last3 = Cradic | first3 = M.&nbsp;S. | last4 = Finkelstein | first4 = I. | last5 = Lipschits | first5 = O. | last6 = Martin | first6 = M.&nbsp;A.&nbsp;S.| last7 = Neumann | first7 = R. | last8 = Stockhammer | first8 = P.&nbsp;W. | last9 = Gadot | first9 = Y.| volume=25 | pages=77–84 | doi=10.1016/j.jasrep.2019.03.034 | bibcode=2019JArSR..25...77L | s2cid=181608839 | url-access = subscription }}</ref><ref name=":0b">{{Cite journal | title=Amir A, Finkelstein I, Shalev Y, Uziel J, Chalaf O, Freud L, et al. (2022) Residue analysis evidence for wine enriched with vanilla consumed in Jerusalem on the eve of the Babylonian destruction in 586 BCE. PLoS ONE 17(3)| year=2022| doi=10.1371/journal.pone.0266085| pmid=35349581| doi-access=free| last1=Amir| first1=A.| last2=Finkelstein| first2=I.| last3=Shalev| first3=Y.| last4=Uziel| first4=J.| last5=Chalaf| first5=O.| last6=Freud| first6=L.| last7=Neumann| first7=R.| last8=Gadot| first8=Y.| journal=PLOS ONE| volume=17| issue=3| article-number=e0266085| pmc=8963535}}</ref> Traces of vanillin were also found in wine jars in [[Jerusalem]], which were used by the [[Kingdom of Judah|Judahite]] elite before [[Siege of Jerusalem (587 BC)|the city was destroyed]] in 586&nbsp;BCE.<ref name=":0b" />

Vanilla beans, called ''tlilxochitl,'' were discovered and cultivated as a flavoring for beverages by native Mesoamerican peoples, most famously the Totonacs of modern-day [[Veracruz]], Mexico. Since at least the early 15th century, the [[Aztecs]] used vanilla as a flavoring for [[chocolate]] in drinks called ''xocohotl''.<ref>{{Cite web |last=MexicanVanilla.com |title=Mexican Vanilla - A History |url=https://mexicanvanilla.com/pages/history-of-vanilla |access-date=2022-06-14 |website=MexicanVanilla.com |language=en}}</ref>

== Synthetic history ==
Vanillin was first isolated as a relatively pure substance in 1858 by [[Théodore Nicolas Gobley]], who obtained it by evaporating a vanilla extract to dryness and [[recrystallization (chemistry)|recrystallizing]] the resulting solids from hot water.<ref>[[#gobley1858|Gobley 1858]].</ref> In 1874, the German scientists [[Ferdinand Tiemann]] and [[Wilhelm Haarmann]] deduced its chemical structure, at the same time finding a synthesis for vanillin from [[coniferin]], a [[glucoside]] of [[coniferyl alcohol]] found in [[pine]] bark.<ref>[[#tiemann1874|Tiemann 1874]].</ref> Tiemann and Haarmann founded a company Haarmann and Reimer (now part of [[Symrise]]) and started the first industrial production of vanillin using their process (now known as the [[Reimer–Tiemann reaction]]) in [[Holzminden]], Germany. In 1876, [[:de:Karl Reimer|Karl Reimer]] synthesized vanillin ('''2''') from guaiacol ('''1''').<ref>[[#reimer1876|Reimer 1876]].</ref>
[[File:Synthesis vanillin 3.svg|300px|thumb|center|Total synthesis of vanillin by Reimer]]

By the late 19th century, semisynthetic vanillin derived from the eugenol found in [[clove oil]] was commercially available.{{efn|According to [[#hocking1997|Hocking 1997]], synthetic vanillin was sold commercially in 1874, the same year Tiemann and Haarmann's original synthesis was published.  Haarmann and Reimer, one of the corporate ancestors of the modern flavor and aroma manufacturer Symrise, was in fact established in 1874.  However, [[#esposito1997|Esposito 1997]] claims that synthetic vanillin first became available in 1894 when Rhône-Poulenc (since 1998, [[Rhodia (company)|Rhodia]]) entered the vanillin business.  If the former claim is correct, the authors of the latter article, being employees of Rhône-Poulenc, may have been unaware of any previous vanillin manufacture.}}

Synthetic vanillin became significantly more available in the 1930s, when production from clove oil was supplanted by production from the [[lignin]]-containing waste produced by the [[sulfite pulping process]] for preparing wood pulp for the [[paper industry]].  By 1981, a single pulp and paper mill in [[Thorold, Ontario]], supplied 60% of the world market for synthetic vanillin.<ref name="#hocking1997|Hocking 1997">[[#hocking1997|Hocking 1997]].</ref>  However, subsequent developments in the wood pulp industry have made its lignin wastes less attractive as a raw material for vanillin synthesis.  Today, approximately 15% of the world's production of vanillin is still made from lignin wastes,<ref name="Fache et al 2015">[[#fache2015|Fache et al 2015]]</ref> while approximately 85% is synthesized in a two-step process from the [[petrochemical]] precursors [[guaiacol]] and [[glyoxylic acid]].<ref name="#esposito1997|Esposito 1997">[[#esposito1997|Esposito 1997]].</ref><ref>{{cite book |author1=Kamlet, Jonas |author2=Mathieson, Olin |name-list-style=amp |title=Manufacture of vanillin and its homologues U.S. Patent 2,640,083 |year=1953 |publisher=U.S. Patent Office |url=https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US2640083.pdf |author1-link=Jonas Kamlet }}</ref>

Beginning in 2000, [[Rhodia (company)|Rhodia]] began marketing biosynthetic vanillin prepared by the action of microorganisms on [[ferulic acid]] extracted from [[rice bran]].  This product, sold at [[USD]]$700/kg under the trademarked name Rhovanil Natural, is not cost-competitive with petrochemical vanillin, which sells for around US$15/kg.<ref>[[#rouhi2003|Rouhi 2003]].</ref> However, unlike vanillin synthesized from lignin or guaiacol, it can be labeled as a natural flavoring.

== Occurrence ==
[[File:Vanilla fragrans 2.jpg|thumb|upright|left|These green seed pods contain vanillin only in its glucoside form, and lack the characteristic odor of vanilla.]]
Vanillin is most prominent as the principal flavor and aroma compound in [[vanilla]]. Cured vanilla pods contain about 2% by dry weight vanillin. Relatively pure vanillin may be visible as a white dust or "frost" on the exteriors of cured pods of high quality.

It is also found in ''[[Leptotes bicolor]]'', a species of orchid native to Paraguay and southern Brazil,<ref name= floralibrary>{{cite web |url=http://www.floralibrary.com/flora/leptotes/bicolor |title=Leptotes bicolor |publisher=Flora Library |access-date=2011-08-21 |archive-date=2021-04-30 |archive-url=https://web.archive.org/web/20210430151909/http://www.floralibrary.com/flora/leptotes/bicolor }}</ref> and the [[Pinus tabuliformis|Southern Chinese red pine]].

At lower concentrations, vanillin contributes to the flavor and aroma profiles of foodstuffs as diverse as [[olive oil]],<ref>[[#brenes1999|Brenes 1999]].</ref> [[butter]],<ref>[[#adahchour1999|Adahchour 1999]].</ref> [[raspberry]],<ref>[[#roberts1996|Roberts 1996]].</ref> and [[lychee]]<ref>[[#ong1998|Ong 1998]].</ref> fruits.

Aging in [[Oak (wine)|oak barrels]] imparts vanillin to some [[wine]]s, [[vinegar]],<ref>{{cite journal | doi = 10.1007/BF01192948 | volume=199 | title=Analysis of polyphenolic compounds of different vinegar samples | year=1994 | journal=Zeitschrift für Lebensmittel-Untersuchung und -Forschung | pages=29–31 | last1 = Carrero Gálvez| first1 = Miguel | s2cid=91784893 }}.</ref> and [[distilled beverage|spirit]]s.<ref>[[#viriot1993|Viriot 1993]].</ref>

In other foods, heat treatment generates vanillin from other compounds.  In this way, vanillin contributes to the flavor and aroma of [[coffee]],<ref>{{Cite journal | doi = 10.1002/ffj.2730100102 | title = Determination of potent odourants in roasted coffee by stable isotope dilution assays | year = 1995 | last1 = Semmelroch | first1 = P. | last2 = Laskawy | first2 = G. | last3 = Blank | first3 = I. | last4 = Grosch | first4 = W. | journal = Flavour and Fragrance Journal | volume = 10 | pages = 1–7}}</ref><ref>[[#blank1992|Blank 1992]].</ref> [[maple syrup]],<ref>[[#kermasha1995|Kermasha 1995]].</ref> and [[whole-grain]] products, including corn [[tortilla]]s<ref>[[#buttery1995|Buttery 1995]].</ref> and [[oatmeal]].<ref>[[#guth1993|Guth 1993]].</ref>

==Production==
{{anchor|Chemistry}}

===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" />

===Chemical synthesis===
The demand for vanilla flavoring has long exceeded the supply of vanilla beans. {{As of|2001}}, the annual demand for vanillin was 12,000 tons, but only 1,800 tons of natural vanillin were produced.<ref>[[#dignum2001|Dignum 2001]].</ref> The remainder was produced by [[chemical synthesis]]. Vanillin was first synthesized from eugenol (found in oil of clove) in 1874–75, less than 20 years after it was first identified and isolated. Vanillin was commercially produced from eugenol until the 1920s.<ref>[[#hocking1997|Hocking 1997]].  This chemical process can be conveniently carried out on the laboratory scale using the procedure described by [[#lampman1977|Lampman 1977]].</ref> Later it was synthesized from lignin-containing "brown liquor", a byproduct of the [[sulfite process]] for making [[wood pulp]].<ref name="#hocking1997|Hocking 1997"/> Counterintuitively, though it uses waste materials, the lignin process is no longer popular because of environmental concerns, and today most vanillin is produced from [[guaiacol]].<ref name="#hocking1997|Hocking 1997"/> Several routes exist for synthesizing vanillin from guaiacol.<ref>[[#vanness1983|Van Ness 1983]].</ref>

At present, the most significant of these is the two-step process practiced by [[Rhodia (company)|Rhodia]] since the 1970s, in which guaiacol ('''1''') reacts with [[glyoxylic acid]] by [[electrophilic aromatic substitution]].<ref>{{cite journal |author1=Fatiadi, Alexander |author2=Schaffer, Robert |name-list-style=amp |title=An Improved Procedure for Synthesis of {{sc|DL}}-4-Hydroxy-3-methoxymandelic Acid ({{sc|DL}}-"Vanillyl"-mandelic Acid, VMA) |journal=Journal of Research of the National Bureau of Standards Section A |year=1974 |volume=78A |issue=3 |pages=411–412 |doi=10.6028/jres.078A.024|pmid=32189791 |pmc=6742820 |doi-access=free }}</ref> The resulting [[vanillylmandelic acid]] ('''2''') is then converted by 4-hydroxy-3-methoxyphenylglyoxylic acid ('''3''') to vanillin ('''4''') by oxidative decarboxylation.<ref name="#esposito1997|Esposito 1997"/>
: [[File:Synthesis vanillin 4.svg|600px]]

Although guaiacol can be obtained by pyrolysis of wood, the type intended for vanillin production is mainly produced by petrochemistry.<ref name=Bomg/><ref name="#hocking1997|Hocking 1997"/>

====Wood-based vanillin====
15% of the world's production of vanillin is produced from [[lignosulfonates]], a byproduct from the manufacture of [[cellulose]] via the [[sulfite process]].<ref name="#hocking1997|Hocking 1997"/><ref name="Fache et al 2015"/> The sole remaining producer of wood-based vanillin is the company [[Borregaard]] located in [[Sarpsborg]], [[Norway]].<ref name=Bomg/> For this kind of use, softwood is preferred because there are more guaiacyl units convertible to vanillin.<ref name="#hocking1997|Hocking 1997"/>

Early production of wood-based vanillin involved four plants: a sulfite pulp mill, a fermentation plant, a vanillin plant, and a Kraft (sulfate) pulp mill. The sulfite mill provides the brown liquor to the fermentation plant, which makes use of the residual sugar. The spend liquor is sent to the vanillin plant, which uses alkaline oxidation with air at 160–170 °C and 10–12 atm pressure, toluene extraction, and back-extraction with NaOH to obtain a crude sodium vanillate. Addition of [[sulfurous acid]] affords easy separation of the soluble sulfide addition compound of vanillin from insoluble impurities such as [[acetovanillone]]. The vanillin is extracted, and the remaining liquor is sent to the Kraft mill for burning to recover energy and sodium sulfide, both important for a Kraft mill.<ref name="#hocking1997|Hocking 1997"/> This process went out of favor in North America due to the large amounts of caustic liquids that needs to be disposed by the mill at the end: 160&nbsp;kg for every 1&nbsp;kg of vanillin produced. The recovery of sodium sulfide also became less and less profitable as the sodium-to-sulfur ratio became more and more unbalanced.<ref name="#hocking1997|Hocking 1997"/>

Borregaard is able to keep operating because it runs its own pulp mill. They have improved a process from Monsanto by using ultrafiltration<ref name="#hocking1997|Hocking 1997"/> to concentrate the incoming [[lignosulfonates]], which reduces the amount of NaOH used and waste produced. The basic chemistry is unchanged: alkaline oxidation using a metal catalyst such a copper salt.<ref>{{cite web |last1=Evju |first1=Hans |title=Process for preparation of 3-methoxy-4-hydroxybenzaldehyde |url=https://patents.google.com/patent/US4151207A |date=24 April 1979}}</ref><ref>[[#bjorsvik1999|Bjørsvik and Minisci 1999]]</ref> According to ''Scientific American'', vanillin produced this way contains aromatic impurities that add strength and creaminess to its flavor.<ref name=Bomg/> This is probably due to [[acetovanillone]] being present.{{efn|name=lig-vanillone}}

===Fermentation===
The company Evolva has developed a genetically modified yeast which can produce vanillin. Because the microbe is a [[processing aid]], the resulting vanillin would not fall under U.S. GMO labeling requirements, and because the production is nonpetrochemical, food using the ingredient can be said to contain no artificial ingredients.<ref name=Bomg>{{Cite web|last=Bomgardner|first=Melody M.|date=2016-09-14|title=The Problem with Vanilla|url=https://www.scientificamerican.com/article/the-problem-with-vanilla/|access-date=2020-10-19|website=Scientific American|language=en}}</ref> The biosynthetic process starts with glucose, or any sugar that can be converted into erythrose 4-phosphate (which leads to 3-dehydroshikimic acid).<ref>{{cite web |last1=Hansen |first1=Joergen |last2=Hansen |first2=Esben Halkjaer |last3=SOMPALLI |first3=Honey Polur |last4=Sheridan |first4=Joseph M. |last5=Heal |first5=Jonathan R. |last6=Hamilton |first6=William D. O. |title=WO2013022881A1 Compositions and methods for the biosynthesis of vanillin or vanillin beta-d-glucoside |url=https://patents.google.com/patent/WO2013022881A1/en |language=en |date=14 February 2013}}</ref> The end product is 98% pure and is also considered natural in the EU.<ref name=Agostini>{{cite web |last1=Agostini |first1=Francesca Degli |title=Sustainable natural vanillin production through yeast fermentation - Europabio |url=https://www.europabio.org/sustainable-natural-vanillin-production-through-yeast-fermentation/ |date=3 October 2024}}</ref>

Using [[ferulic acid]] (a chemical found in rice) as an input and a specific non GMO species of ''[[Amycolatopsis]]'' bacteria, vanillin can be produced. Many other bacteria, either GMO or non-GMO, can be used for the same purpose. However, because vanillin inhibits the growth of free-floating bacteria, yields have been low. This can be overcome through the formation of [[biofilms]], which has been done with the non-GMO ''[[Bacillus subtilis|B. subtilis]]'' strain CCTCC M2011162.<ref>{{cite journal |last1=Yan |first1=Lei |last2=Chen |first2=Peng |last3=Zhang |first3=Shuang |last4=Li |first4=Suyue |last5=Yan |first5=Xiaojuan |last6=Wang |first6=Ningbo |last7=Liang |first7=Ning |last8=Li |first8=Hongyu |title=Biotransformation of ferulic acid to vanillin in the packed bed-stirred fermentors |journal=Scientific Reports |date=6 October 2016 |volume=6 |issue=1 |article-number=34644 |doi=10.1038/srep34644|pmid=27708366 |pmc=5052561 |bibcode=2016NatSR...634644Y }}</ref> However, using ferulic acid as the starting material does not qualify for "natural ingredient" in the EU.<ref name=Agostini/>

Biotransformation of eugenol (from cloves) into vanillin by non-GMO microorganisms has also been reported.<ref>{{cite journal |last1=Singh |first1=Archana |last2=Mukhopadhyay |first2=Kunal |last3=Ghosh Sachan |first3=Shashwati |title=Biotransformation of eugenol to vanillin by a novel strain Bacillus safensis SMS1003 |journal=Biocatalysis and Biotransformation |date=4 July 2019 |volume=37 |issue=4 |pages=291–303 |doi=10.1080/10242422.2018.1544245}}</ref> The same has been reported for guaiacol and guaicyl lignin (from conifers).<ref>{{cite journal |last1=Xu |first1=Lingxia |last2=Liaqat |first2=Fakhra |last3=Sun |first3=Jianzhong |last4=Khazi |first4=Mahammed Ilyas |last5=Xie |first5=Rongrong |last6=Zhu |first6=Daochen |title=Advances in the vanillin synthesis and biotransformation: A review |journal=Renewable and Sustainable Energy Reviews |date=January 2024 |volume=189 |article-number=113905 |doi=10.1016/j.rser.2023.113905|bibcode=2024RSERv.18913905X }}</ref><ref>{{cite journal |last1=Zuo |first1=Kangjia |last2=Li |first2=Huanan |last3=Chen |first3=Jianhui |last4=Ran |first4=Qiuping |last5=Huang |first5=Mengtian |last6=Cui |first6=Xinxin |last7=He |first7=Lili |last8=Liu |first8=Jiashu |last9=Jiang |first9=Zhengbing |title=Effective Biotransformation of Variety of Guaiacyl Lignin Monomers Into Vanillin by Bacillus pumilus |journal=Frontiers in Microbiology |date=11 May 2022 |volume=13 |doi=10.3389/fmicb.2022.901690|doi-access=free |pmid=35633711 |pmc=9130762 }}</ref> These starting materials do not qualify for "natural ingredient" in the EU.<ref name=Agostini/>

== Uses ==
[[File:Butter-Vanille-Aroma.JPG|thumb|right|140px|Butter-vanilla flavoring]]
The largest use of vanillin is as a flavoring, usually in [[sweetness|sweet]] foods.  The [[Vanilla ice cream|ice cream]] and [[chocolate]] industries together comprise 75% of the market for vanillin as a flavoring, with smaller amounts being used in [[confection]]s and [[baked goods]].<ref>[[#fridge2004|FRIDGE 2004]], p. 33.</ref>

Vanillin is also used in the fragrance industry, in [[perfume]]s, and to mask unpleasant odors or tastes in medicines, livestock [[fodder]], and cleaning products.<ref name="#esposito1997|Esposito 1997"/> It is also used in the flavor industry, as a very important key note for many different flavors, especially creamy profiles such as [[cream soda]].

Additionally, vanillin can be used as a general-purpose stain for visualizing spots on [[thin-layer chromatography]] plates.  This stain yields a range of colors for these different components.

===Biochemistry===
Several studies have suggested that vanillin can affect the performance of [[antibiotics]] [[in vitro|in laboratory conditions]].<ref>{{cite journal |last1=Brochado|first1=Ana|date=4 July 2018|title=Species-specific activity of antibacterial drug combinations|journal=[[Nature (journal)|Nature]]|volume=559|issue=7713|pages=259–263|doi=10.1038/s41586-018-0278-9|pmid=29973719|pmc=6219701|bibcode=2018Natur.559..259B}}</ref><ref>{{cite journal |last1=Bezzera|first1=Camila|date=1 December 2017|title=Vanillin selectively modulates the action of antibiotics against resistant bacteria.|journal=Microbial Pathogenesis|volume=113|pages=265–268|doi=10.1016/j.micpath.2017.10.052|pmid=29107747}}</ref>

[[Vanillin–HCl staining]] can be used to visualize the localisation of tannins in cells.

===Manufacturing===
Vanillin has been used as a chemical intermediate in the production of [[pharmaceuticals]], [[cosmetics]], and other [[fine chemicals]].<ref>{{cite journal |pmid=17886091 |year=2008 |last1=Sinha |first1=A. K. |title=A comprehensive review on vanilla flavor: Extraction, isolation and quantification of vanillin and others constituents |journal=International Journal of Food Sciences and Nutrition |volume=59 |issue=4 |pages=299–326 |last2=Sharma |first2=U. K. |last3=Sharma |first3=N. |doi=10.1080/09687630701539350|s2cid=37559260 }}</ref> In 1970, more than half the world's vanillin production was used in the synthesis of other chemicals.<ref name="#hocking1997|Hocking 1997"/> As of 2016, vanillin uses have expanded to include [[perfume]]s, flavoring and aromatic masking in medicines, various consumer and cleaning products, and [[livestock]] foods.<ref>{{cite web |url=http://www.prnewswire.com/news-releases/global-vanillin-market-research-report---industry-analysis-size-share-growth-trends-and-forecast-2015---2022-300328321.html |title=Global Vanillin Market Research Report – Industry Analysis, Size, Share, Growth, Trends and Forecast 2015–2022 |date=14 September 2016 |publisher=PRNewsire |access-date=18 February 2017}}</ref>

Vanillin is becoming a popular choice for the development of bio-based plastics.<ref>{{cite journal |doi = 10.1016/j.eurpolymj.2015.03.050 |year = 2015 |title= Vanillin, a key-intermediate of biobased polymers |journal = European Polymer Journal |volume=68 |pages=488–502 |last1=Fache |first1=Maxence  |last2=Boutevin |first2=Bernard |last3=Caillol |first3=Sylvain|bibcode = 2015EurPJ..68..488F }}</ref>

== Adverse effects ==
Vanillin can trigger [[migraine headache]]s in a small fraction of the people who experience migraines.<ref name="Saint Denis-1996">{{Cite journal | author= Saint Denis, M. | author2 = Coughtrie, M. W. | author3 = Guilland, J. C. | author4 = Verges, B. | author5 = Lemesle, M. | author6 = Giroud, M. | title = Migraine induced by vanillin | journal = Presse Méd. | volume = 25 | issue = 40 | page = 2043 |date=Dec 1996 | pmid = 9082382}}</ref>{{dubious|date=December 2025}}{{citation needed|date=December 2025}}

Some people have [[allergic reactions]] to vanilla.<ref>{{cite journal | pmc = 1245616 | date = 1987 | last1 = Van Assendelft | first1 = A. H. | title = Adverse drug reactions checklist | journal = British Medical Journal (Clinical Research Ed.) | volume = 294 | issue = 6571 | pages = 576–577 | doi = 10.1136/bmj.294.6571.576-d | pmid = 3103791 }}</ref> They may be allergic to synthetically produced vanilla but not to natural vanilla, or the other way around, or to both.<ref name=":0a">{{Cite book|last1=Rietschel|first1=Robert L.|url=https://books.google.com/books?id=dQBAzfyCeQ8C&q=vanillin+allergy&pg=PA444|title=Fisher's Contact Dermatitis|last2=Fowler|first2=Joseph F.|last3=Fisher|first3=Alexander A.|date=2008|publisher=PMPH-USA|isbn=978-1-55009-378-0|page=444|language=en}}</ref>

Vanilla orchid plants can trigger [[contact dermatitis]], especially among people working in the vanilla trade if they come into contact with the plant's sap.<ref name=":0a" />  An allergic contact dermatitis called vanillism produces swelling and redness, and sometimes other symptoms.<ref name=":0a" /> The sap of most species of vanilla orchid which exudes from cut stems or where beans are harvested can cause moderate to severe dermatitis if it comes in contact with bare skin. The sap of vanilla orchids contains [[calcium oxalate]] crystals, which are thought to be the main causative agent of contact dermatitis in vanilla plantation workers.<ref>{{cite web|url=http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:262578-2|title=Vanilla planifolia Andrews - Plants of the World Online - Kew Science|website=powo.science.kew.org|url-status=live|archive-url=https://web.archive.org/web/20171122013549/http://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:262578-2|archive-date=22 November 2017|df=dmy-all}}</ref><ref>{{PFAF |url-status=live |archive-url=https://web.archive.org/web/20171201033211/http://pfaf.org/user/Plant.aspx?LatinName=Vanilla+planifolia |archive-date=1 December 2017 |df=dmy-all}}</ref>

A pseudophytodermatitis called vanilla lichen can be caused by handling vanilla pods. It is not caused by vanilla itself but [[flour mite]]s (''Tyroglyphus farinae'').<ref name=":0a" />

== Ecology ==
''[[Scolytus multistriatus]]'', one of the vectors of the [[Dutch elm disease]], uses vanillin as a signal to find a host tree during [[oviposition]].<ref>{{cite journal|title = Vanillin and Syringaldehyde as Attractants for Scolytus multistriatus (Coleoptera: Scolytidae)|last1= Meyer|first1=H.J.|last2= Norris|first2=D.M.|journal= Annals of the Entomological Society of America|date= 17 July 1967| volume= 60|number= 4| pages= 858–859 |doi = 10.1093/aesa/60.4.858}}</ref>

== See also ==
* [[Phenolic compounds in wine]]
* Other [[positional isomer]]s:
** [[Isovanillin]]
** [[ortho-Vanillin|''ortho''-Vanillin]]
** [[2-Hydroxy-5-methoxybenzaldehyde]]
** [[2-Hydroxy-4-methoxybenzaldehyde]]
* [[Benzaldehyde]]
* [[Protocatechuic aldehyde]]
* [[Syringaldehyde]]

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{{refend}}

== Notes ==
{{notelist}}
{{reflist}}

{{Transient receptor potential channel modulators}}
{{Authority control}}

[[Category:Flavors]]
[[Category:Perfume ingredients]]
[[Category:4-Hydroxybenzaldehyde derivatives]]
[[Category:Vanilloids]]
[[Category:O-methylated natural phenols]]
[[Category:Vanilla]]
[[Category:Total synthesis]]
[[Category:Tree-derived bioactive compounds]]