Making Vanillin – Three production routes & Their chemistry

Vanilla is one of the most common and popular flavours in food. Are there ice cream shops that do not sell a vanilla ice cream? There are several ways to make food taste like vanilla. You can either use pure vanilla, or you can use (artificial) vanillin. Since we’ve discussed the different uses and origins of vanilla vs. vanillin, we’ll focus solely on making vanillin today.

Pure vanilla originates from vanilla beans and is a complex mixture of flavour molecules. However, there’s one molecule which has the largest contribution to the vanilla flavour: vanillin. Vanillin occurs in vanilla beans, but, it can also be made without the intervention of a single vanilla bean. It’s a molecule that can be made relatively easily using chemical reactions.

Vanillin molecule

Vanillin is just one molecule, shown below. It’s molecular formula is C8H8O3 and one of its chemical names is: 4-hydroxy-3-methoxybenzaldehyde. 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.

vanillin

Making vanillin from eugenol

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.

eugenol

When converting eugenol to vanillin two chemical process steps have to take place:

  1. Isomerization of the eugenol: in other words, the double bond of the eugenol will move from the top to one position lower.
  2. Oxidation of the isoeugenol, thus adding that oxygen group.

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.

Lignin (wood pulp) to make vanillin

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.

lingin structure source wikipedia

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 vanilling from both lignin as well as guaiacol. Big steps have been made and are being made

Using yeast to make vanillin (natural)

Developments do continue within the world of vanillin production. In recent years the wish for natural vanillin has increased under consumers. However, most harsh chemical processes described above do not fit that definition. A comming route that various companies look into for making natural vanillin though is the use of micro organisms. Certain yeasts, fungi and bacteria can be used to make vanillin from other (naturally occuring) molecules.

Several processes are already used to make vanillin with the use of micro organisms. That said, it is not easy to get these processes to work efficiently. One of the most interesting factors at play I found was the fact that vanillin is actually toxic to several micro organisms. So the concentrations the micro organisms make themselves have to be kept low to prevent them from dying.

If you’re interested in more chemical details I would suggest reading this article which has a very extensive analysis of the various routes being investigated.

Sources

There are several patents available describing in more detail how to make vanillin from eugenol, here is one example.

In the 1970’s a teacher designed a nice classroom experiment allowing students to make vanillin from eugenol themselves.

A very complete research article about the history of vanillin synthesis.

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