Once it was discovered that vanilla orchids could be fertilised manually, production of vanilla spread well beyond Central America. Freshly picked vanilla pods do not smell of vanilla, because the vanillin molecule is immobilised by being bound to glucose as a beta-D-glycoside. Enzymes get to work when the pods are cured; the pods gradually turn brown and shrivel up, and free vanillin molecules are liberated. The smell of vanilla is due to different odorant molecules, but vanillin is the main one.
Since the 19th century, demand has vastly outstripped production of natural vanilla, so people found ways of making synthetic vanillin. Nowadays over 95 per cent of vanilla flavouring comes from synthetic sources; people are so used to synthetic 'vanilla' flavour that they prefer it to the real thing, and may wonder about the tiny specks of vanilla seeds they find in an up-market ice cream.
Along with the chocolate industry, ice cream uses about 75 per cent of vanilla flavouring, together with other foodstuffs like Coca-Cola and baked foods. Chemists use vanillin in many syntheses, such as to make L-dopa, the Parkinson's disease drug, the antibacterial compound trimethoprin, and the heart drug papaverin.
Vanillin solutions are used to develop thin layer chromatography plates, showing different types of compounds in different colours, and filling the lab with a heady scent. The plant makes vanillin from the aminoacid phenylalanine. In the 19th century, chemists discovered ways of making it from eugenol, found naturally in cloves, nutmeg and cinnamon, and from guaiacol, which they got from pine tar.
Another source is breakdown of lignin, a strengthening material in wood and plants. Storing wine or whisky in oak casks leads to vanillin molecules appearing in the drink, and cooking over wooden fires can likewise give a vanilla edge to the flavour of food. In the past, a lot of vanillin came from the waste from paper mills. Recently, a Japanese scientist, Mayu Yamamoto, found a novel way of making vanillin. She extracted lignin from cow dung and converted that to vanillin.
This discovery won her the Ig Nobel prize for chemistry, the send-up of the real Nobel prize. Natural vanilla extract costs up to times that of a man-made substitute, so there is a lot of fake vanilla extract on the market. The easiest way to tell real and synthetic vanilla essence apart is to use Gas-Liquid Chromatography, which can spot the impurities like 4-hydroxybenzaldehyde present in natural vanilla essence, but the fakers can simply add these molecules.
Another way is to look at the radiocarbon content, the amount of radioactive carbon Natural plant-sourced vanillin contains a certain level of carbon, but since the half life of carbon is years, vanillin derived from crude oil has no radiocarbon, since it has decayed away over the millions of years the oil was trapped underground.
But determined forgers started putting some carbon adulterated molecules into their fake vanilla extract. To counter that, the analysts started looking at the ratio of the natural isotopes, carbon and carbon Because the vanilla orchid uses a different biosynthetic pathway to other plants, orchid-derived vanillin has a greater ratio of carbon to carbon than synthetic vanillin.
The fraudsters hit back by doping their synthetic vanillin with molecules containing extra carbon Pure vanillin is generally sold as a crystalline powder and is white maybe slightly yellowish. Vanillin can be bought with a wide variety of suppliers which may use several different routes to make vanillin. There are roughly two ways to make vanillin. The first is to find a more common molecule that already exists in nature and transform it into vanilla using various chemical reactions.
The other method uses yeasts to make vanillin molecules from pretty different molecules. Vanillin is an expensive ingredient, so it stimulates the industry to look for cheaper ways to make the product. One of these ways is to take molecules that occur in natur in higher quantities thus are cheaper and convert those into vanillin. Eugenol is such a molecule. Eugenol can be extracted from spices such as cinnamon, nutmeg and cloves. Its structure is very similar to that of vanillin as you can see in the structure shown below source.
The only difference sits in the top branch where it lacks the oxygen O group and instead has a longer carbon tail. Look into the sources at the bottom of this post to find more detailed articles and patents , describing the chemical steps and processes in more detail. Despite eugenol being a slightly cheaper way to make vanillin, development has continued and nowadays most of the vanillin is not made from eugenol anymore, instead it is made from lignin and guaiacol.
The image below shows an illustration of how lignin could look like source. If you look closely you can again recognize the structure of the vanillin molecule. There are several ways to make vanillin from lignin. The easiest processes however tend to use a lot of harsh chemical solvents or very strong acids and bases which makes them very environmentally unfriendly.
Therefore, a lot of research is done into better ways of making vanillin from both lignin as well as guaiacol. Big steps have been made and are being made.
Kirk-Othmer Encyclopedia of Chemical Technology, 4th edition National Economic Development and Labor Council. Gobley, N. Journal de Pharmacie et de Chimie 34 : Guth, Helmut; and Werner Grosch Hocking, Martin B. September Journal of Chemical Education 74 9 : Kermasha, S. Goetghebeur, and J. Dumont Journal of Agricultural and Food Chemistry 43 3 : Lampman, Gary M. Journal of Chemical Education 54 12 : Ong, Peter K.
Acree Journal of Agricultural and Food Chemistry 46 6 : Reimer, K. Berichte der deutschen chemischen Gesellschaft 9 1 : Roberts, Deborah D.
Journal of Agricultural and Food Chemistry 44 12 : Rouhi, A. Maureen Chemical and Engineering News 81 28 : Tiemann, Ferd. Berichte der Deutschen Chemischen Gesellschaft 7 1 : Van Ness, J. Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edition Journal of Agricultural and Food Chemistry 41 11 : Walton, Nicholas J. Mayer, and Arjan Narbad July Phytochemistry 63 5 : — Guaiacol vanillin, adulterated with acetovanillone, has an odor indistinguishable from lignin vanillin.
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. This chemical process can be conveniently carried out on the laboratory scale using the procedure described by Lampman Topics A-Z.
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