Vanillin

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Vanillin
Skeletal formula of a vanillin minor tautomer Spacefill model of a vanillin minor tautomer
Identifiers
CAS number 121-33-5 YesY
PubChem 1183
ChemSpider 13860434 YesY
UNII CHI530446X YesY
EC number 204-465-2
KEGG D00091 YesY
MeSH vanillin
ChEBI CHEBI:18346 YesY
ChEMBL CHEMBL13883 YesY
RTECS number YW5775000
Beilstein Reference 472792
Gmelin Reference 3596
3DMet B00167
Jmol-3D images Image 1
Properties
Molecular formula C8H8O3
Molar mass 152.15 g mol−1
Appearance White crystals
Odor Vanilla, Sweet, Balsamic, Pleasant
Density 1.056 g cm−3
Melting point 81 to 83 °C; 178 to 181 °F; 354 to 356 K
Boiling point 285 °C (545 °F; 558 K)
Solubility in water 10 g dm−3
log P 1.208
Vapor pressure >1 Pa
Acidity (pKa) 7.781
Basicity (pKb) 6.216
Structure
Crystal structure Monoclinic
Thermochemistry
Std enthalpy of
combustion
ΔcHo298
−3.828–3.828 MJ mol−1
Hazards
MSDS hazard.com
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word WARNING
GHS hazard statements H302, H317, H319
GHS precautionary statements P280, P305+351+338
EU classification Harmful Xn
R-phrases R22
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 147 °C (297 °F; 420 K)
Related compounds
Related compounds Anisaldehyde

Eugenol
Phenol
Vanillyl alcohol

Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Vanillin is a phenolic aldehyde, which is an organic compound with the molecular formula C8H8O3. Its functional groups include aldehyde, hydroxyl, and ether. It is the primary component of the extract of the vanilla bean. Synthetic vanillin, instead of natural vanilla extract, is now more often used as a flavoring agent in foods, beverages, and pharmaceuticals.

Vanillin and ethylvanillin are used by the food industry; ethylvanillin is more expensive, but has a stronger note. It differs from vanillin by having an ethoxy group (–O–CH2CH3) instead of a methoxy group (–O–CH3).

Natural "vanilla extract" is a mixture of several hundred different compounds in addition to vanillin. Artificial vanilla flavoring is often a solution of pure vanillin, usually of synthetic origin. Because of the scarcity and expense of natural vanilla extract, there has long been interest in the synthetic preparation of its predominant component. The first commercial synthesis of vanillin began with the more readily available natural compound eugenol. Today, artificial vanillin is made either from guaiacol or from lignin.

Vanillin crystals extracted from vanilla extract.

Lignin-based artificial vanilla flavoring is alleged to have a richer flavor profile than oil-based flavoring; 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.[3]

History[edit]

Vanilla was cultivated as a flavoring by pre-Columbian Mesoamerican people; at the time of their conquest by Hernán Cortés, the Aztecs used it as a flavoring for chocolate. Europeans became aware of both chocolate and vanilla around 1520.[4]

Vanillin was first isolated as a relatively pure substance in 1858 by Nicolas-Theodore Gobley, who obtained it by evaporating a vanilla extract to dryness, and recrystallizing the resulting solids from hot water.[5] 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 isoeugenol found in pine bark.[6] Tiemann and Haarmann founded a company, Haarmann & Reimer (now part of Symrise) and started the first industrial production of Vanillin using their process in Holzminden (Germany). In 1876, Karl Reimer synthesized vanillin (2) from guaiacol (1).[7]

Synthesis vanillin 3.svg
Synthesis of Vanillin by Reimer

By the late 19th century, semisynthetic vanillin derived from the eugenol found in clove oil was commercially available.[8]

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 Ontario supplied 60% of the world market for synthetic vanillin.[9] However, subsequent developments in the wood pulp industry have made its lignin wastes less attractive as a raw material for vanillin synthesis. While some vanillin is still made from lignin wastes, most synthetic vanillin is today synthesized in a two-step process from the petrochemical precursors guaiacol and glyoxylic acid.[4][10]

Beginning in 2000, Rhodia began marketing biosynthetic vanillin prepared by the action of microorganisms on ferulic acid extracted from rice bran. At $700/kg, this product, sold under the trademarked name Rhovanil Natural, is not cost-competitive with petrochemical vanillin, which sells for around $15/kg.[11] However, unlike vanillin synthesized from lignin or guaiacol, it can be labeled as a natural flavoring.

Occurrence[edit]

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 approximately 2% by dry weight vanillin; on cured pods of high quality, relatively pure vanillin may be visible as a white dust or "frost" on the exterior of the pod.

It is also found in Leptotes bicolor, a species of orchid native to Paraguay and southern Brazil,[12] and the Chinese red pine.

At lower concentrations, vanillin contributes to the flavor and aroma profiles of foodstuffs as diverse as olive oil,[13] butter,[14] raspberry[15] and lychee[16] fruits.

Aging in oak (wine) barrels imparts vanillin to some wines, vinegar[17] and spirits.[18]

In other foods, heat treatment generates vanillin from other chemicals. In this way, vanillin contributes to the flavor and aroma of coffee,[19][20] maple syrup,[21] and whole grain products including corn tortillas[22] and oatmeal.[23]

Production[edit]

Natural production[edit]

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

As harvested, the green seed pods contain vanillin in the form of its β-D-glucoside; the green pods do not have the flavor or odor of vanilla.[24]

Glucovanillin.svg
β-D-glucoside of vanillin

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 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 a dark brown, and enzymes 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,[25] with its focus on producing a premium product by established methods, rather than on innovations that might alter the product's flavor profile.

Vanillin accounts for about 2% of the dry weight of cured vanilla beans, and is the chief among about 200 other flavor compounds found in vanilla.

Biosynthesis[edit]

The biosynthesis of vanillin is achieved by the conversion of tyrosine into 4-coumaric acid then into ferulic acid and finally into vanillin. Vanillin is then converted into its corresponding glucoside.

Biosynthesis of Vanillin From Tyrosine

The conversion of ferulic acid into vanillin is achieved by conversion of the carboxylic acid into a thioester with acetyl-CoA. The feruloyl CoA is then hydrated into 4-hydroxy-3-methoxyphenyl-β-hydroxypropionyl CoA (HMPHP CoA). At this point, two different pathways have been proposed for the conversion of HMPHP CoA into vanillin. One pathway is similar to the β-oxidation of fatty acid, beginning with the oxidation of the hydroxyl group, cleavage to release acetyl-CoA to form a shortened thioester and then cleavage of the thioester into an aldehyde. The other pathway contains one enzyme that would simultaneously oxidize the hydroxyl group along with the release of aceyl-CoA.

Cleavage of Thioester.pdf

Chemical synthesis[edit]

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.[26] 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.[27] Later it was synthesized from lignin-containing "brown liquor", a byproduct of the sulfite process for making wood pulp.[9] Counter-intuitively, even though it uses waste materials, the lignin process is no longer popular because of environmental concerns, and today most vanillin is produced from the petrochemical raw material guaiacol.[9] Several routes exist for synthesizing vanillin from guaiacol.[28]

At present, the most significant of these is the two-step process practiced by Rhodia since the 1970s, in which guaiacol (1) reacts with glyoxylic acid by electrophilic aromatic substitution.[29] The resulting vanillylmandelic acid (2) is then converted via 4-Hydroxy-3-methoxyphenylglyoxylic acid (3) to vanillin (4) by oxidative decarboxylation.[4]

Synthesis vanillin 4.svg

Uses[edit]

Vanilla extract

The largest use of vanillin is as a flavoring, usually in sweet foods. The ice cream and chocolate industries together comprise 75% of the market for vanillin as a flavoring, with smaller amounts being used in confections and baked goods.[30]

Vanillin is also used in the fragrance industry, in perfumes, and to mask unpleasant odors or tastes in medicines, livestock fodder, and cleaning products.[4] It is also used in the flavor industry, as a very important key note for many different flavors, especially creamy profiles like cream soda.

Vanillin has been used as a chemical intermediate in the production of pharmaceuticals and other fine chemicals. In 1970, more than half the world's vanillin production was used in the synthesis of other chemicals,[9] but as of 2004 this use accounts for only 13% of the market for vanillin.[31]

Additionally, vanillin can be used as a general purpose stain for developing thin layer chromatography (TLC) plates to aid in visualizing components of a reaction mixture. This stain yields a range of colors for these different components.

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

Adverse effects[edit]

Vanillin can trigger allergic reactions,[32] as well as migraine headaches in a small fraction of the people who experience migraines.[33]

Ecology[edit]

Scolytus multistriatus, one of the vectors of the Dutch elm disease, uses vanillin as a signal to find a host tree during oviposition.[34]

See also[edit]

References[edit]

  • Adahchour, Mohamed; René J. J. Vreuls, Arnold van der Heijden and Udo A. Th. Brinkman (1999). "Trace-level determination of polar flavour compounds in butter by solid-phase extraction and gas chromatography–mass spectrometry". Journal of Chromatography A 844 (1–2): 295–305. doi:10.1016/S0021-9673(99)00351-9. PMID 10399332. 
  • Blank, Imre; Alina Sen; Werner Grosch (1992). "Potent odorants of the roasted powder and brew of Arabica coffee". Zeitschrift für Lebensmittel-Untersuchung und -Forschung A 195 (3): 239–245. doi:10.1007/BF01202802. 
  • Brenes, Manuel; Aranzazu García; Pedro García; José J. Rios; Antonio Garrido (1999). "Phenolic Compounds in Spanish Olive Oils". Journal of Agricultural and Food Chemistry 47 (9): 3535–3540. doi:10.1021/jf990009o. PMID 10552681. 
  • Buttery, Ron G.; Louisa C. Ling (1995). "Volatile Flavor Components of Corn Tortillas and Related Products". Journal of Agricultural and Food Chemistry 43 (7): 1878–1882. doi:10.1021/jf00055a023. 
  • Dignum, Mark J. W.; Josef Kerlera; Rob Verpoorte (2001). "Vanilla Production: Technological, Chemical, and Biosynthetic Aspects". Food Reviews International 17 (2): 119–120. doi:10.1081/FRI-100000269. Retrieved 2006-09-09. 
  • Esposito, Lawrence J.; K. Formanek; G. Kientz; F. Mauger; V. Maureaux; G. Robert; F. Truchet (1997). "Vanillin". Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition 24. New York: John Wiley & Sons. pp. 812–825. 
  • Fund for Research into Industrial Development, Growth and Equity (FRIDGE) (2004). Study into the Establishment of an Aroma and Fragrance Fine Chemicals Value Chain in South Africa, Part Three: Aroma Chemicals Derived from Petrochemical Feedstocks. National Economic Development and Labor Council. 
  • Gobley, N.-T. (1858). "Recherches sur le principe odorant de la vanille". Journal de Pharmacie et de Chimie 34: 401–405. 
  • Guth, Helmut; Werner Grosch (1995). "Odorants of extrusion products of oat meal: Changes during storage". Zeitschrift für Lebensmittel-Untersuchung und -Forschung A 196 (1): 22–28. doi:10.1007/BF01192979. 
  • Hocking, Martin B. (September 1997). "Vanillin: Synthetic Flavoring from Spent Sulfite Liquor" (PDF). Journal of Chemical Education 74 (9): 1055–1059. doi:10.1021/ed074p1055. Retrieved 2006-09-09. 
  • Kermasha, S.; M. Goetghebeur; J. Dumont (1995). "Determination of Phenolic Compound Profiles in Maple Products by High-Performance Liquid Chromatography". Journal of Agricultural and Food Chemistry 43 (3): 708–716. doi:10.1021/jf00051a028. 
  • Lampman, Gary M.; Jennifer Andrews; Wayne Bratz; Otto Hanssen; Kenneth Kelley; Dana Perry; Anthony Ridgeway (1977). "Preparation of vanillin from eugenol and sawdust". Journal of Chemical Education 54 (12): 776–778. doi:10.1021/ed054p776. 
  • Ong, Peter K. C.; Terry E. Acree (1998). "Gas Chromatography/Olfactory Analysis of Lychee (Litchi chinesis Sonn.)". Journal of Agricultural and Food Chemistry 46 (6): 2282–2286. doi:10.1021/jf9801318. 
  • Reimer, K. (1876). "Ueber eine neue Bildungsweise aromatischer Aldehyde". Berichte der deutschen chemischen Gesellschaft 9 (1): 423–424. doi:10.1002/cber.187600901134. 
  • Roberts, Deborah D.; Terry E. Acree (1996). "Effects of Heating and Cream Addition on Fresh Raspberry Aroma Using a Retronasal Aroma Simulator and Gas Chromatography Olfactometry". Journal of Agricultural and Food Chemistry 44 (12): 3919–3925. doi:10.1021/jf950701t. 
  • Rouhi, A. Maureen (2003). "Fine Chemicals Firms Enable Flavor And Fragrance Industry". Chemical and Engineering News 81 (28): 54. 
  • Tiemann, Ferd.; Wilh. Haarmann (1874). "Ueber das Coniferin und seine Umwandlung in das aromatische Princip der Vanille". Berichte der Deutschen Chemischen Gesellschaft 7 (1): 608–623. doi:10.1002/cber.187400701193. 
  • Van Ness, J. H. (1983). "Vanillin". Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edition 23. New York: John Wiley & Sons. pp. 704–717. 
  • Viriot, Carole; Augustin Scalbert; Catherine Lapierre; Michel Moutounet (1993). "Ellagitannins and lignins in aging of spirits in oak barrels". Journal of Agricultural and Food Chemistry 41 (11): 1872–1879. doi:10.1021/jf00035a013. 
  • Walton, Nicholas J.; Melinda J. Mayer; Arjan Narbad (July 2003). "Vanillin". Phytochemistry 63 (5): 505–515. doi:10.1016/S0031-9422(03)00149-3. 

Notes[edit]

  1. ^ a b PubChem 1183
  2. ^ a b Vanillin
  3. ^ According to 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.
  4. ^ a b c d Esposito 1997
  5. ^ Gobley 1858
  6. ^ Tiemann 1874
  7. ^ Reimer 1876
  8. ^ According to Hocking 1997, synthetic vanillin was sold commercially in 1874, the same year Tiemann and Haarmann's original synthesis was published. Haarmann & Reimer, one of the corporate ancestors of the modern flavor and aroma manufacturer Symrise, was in fact established in 1874. However, Esposito 1997 claims that synthetic vanillin first became available in 1894 when Rhône-Poulenc (since 1998, 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.
  9. ^ a b c d Hocking 1997
  10. ^ Kamlet, Jonas; and Mathieson, Olin (1953). Manufacture of vanillin and its homologues U.S. Patent 2,640,083. U.S. Patent Office. 
  11. ^ Rouhi 2003
  12. ^ "Leptotes bicolor". Flora Library. Retrieved 2011-08-21. 
  13. ^ Brenes 1999
  14. ^ Adahchour 1999
  15. ^ Roberts 1996
  16. ^ Ong 1998
  17. ^ Analysis of polyphenolic compounds of different vinegar samples. Miguel Carrero Gálvez, Carmelo García Barroso and Juan Antonio Pérez-Bustamante, Zeitschrift für Lebensmitteluntersuhung und -Forschung A, Volume 199, Number 1, pages 29-31, doi:10.1007/BF01192948
  18. ^ Viriot 1993
  19. ^ Semmelroch, P.; Laskawy, G.; Blank, I.; Grosch, W. (1995). "Determination of potent odourants in roasted coffee by stable isotope dilution assays". Flavour and Fragrance Journal 10: 1. doi:10.1002/ffj.2730100102.  edit
  20. ^ Blank 1992
  21. ^ Kermasha 1995
  22. ^ Buttery 1995
  23. ^ Guth 1993
  24. ^ Walton 2003
  25. ^ 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.
  26. ^ Dignum 2001
  27. ^ Hocking 1997. This chemical process can be conveniently carried out on the laboratory scale using the procedure described by Lampman 1977.
  28. ^ Van Ness 1983
  29. ^ Fatiadi, Alexander; and Schaffer, Robert (1974). "An Improved Procedure for Synthesis of DL-4-Hydroxy-3-methoxymandelic Acid (DL-"Vanillyl"-mandelic Acid, VMA)". Journal of Research of the National Bureau of Standards - A. Physics and Chemistry 78A (3): 411–412. doi:10.6028/jres.078A.024. Retrieved 19 December 2013. 
  30. ^ FRIDGE 2004, p. 33
  31. ^ FRIDGE 2004, p. 32.
  32. ^ A.H. van Assendelft, "Adverse drug reactions checklist," in the British Medical Journal, February 28th, 1987, pp. 576-577.
  33. ^ Saint Denis, M.; Coughtrie, MW.; Guilland, JC.; Verges, B.; Lemesle, M.; Giroud, M. (Dec 1996). "[Migraine induced by vanillin].". Presse Med 25 (40): 2043. PMID 9082382. 
  34. ^ Vanillin and Syringaldehyde as Attractants for Scolytus multistriatus (Coleoptera: Scolytidae). Meyer H.J. and Norris D.M., Annals of the Entomological Society of America, 17 July 1967, Volume 60, Number 4, pages 858-859, (abstract)