Vanilla extract from orchid pods costs typically
20 times more than synthetic vanillin, and varies with demand and crop
production. This has resulted in counterfeit vanilla essence appearing,
claiming to be the natural extract when it is in fact either purely
synthetic or natural extract diluted with synthetic vanillin. This may
sound a trivial matter, but the integrity of ingredients is a very important
issue in the food industry, and vanilla is one of the most commonly
Spotting the fake
Chromatography can be used to identify simple
fakes. Chromatography separates a mixture like natural vanilla extract
into its chemical components. Comparison of a suspected fake with genuine
vanilla and a standard mixture may reveal there are components missing
or added. Complex fakes are more difficult to identify this way, and
other methods may be used in conjunction.
The vanilla orchid is among a group of plants that
follow a different pathway for photosynthesis compared with most others.
There are fewer steps in this pathway, and this has an effect on the proportion
of carbon-13 atoms present. 13C reacts slightly slower than 12C, and so
the more steps, the lower the proportion in the products.
All sources of synthetic vanillin, including the petrochemical route,
are from plant material using the pathway with more steps. Synthetic vanillin
therefore has a lower proportion of 13C than natural vanilla extract.
The ratio of 13C/12C is found using stable isotope
ratio analysis (SIRA) with a mass spectrometer. From this the "isotopic
deviation" is calculated, with these typical values:
|"Natural" Vanilla from
||16.8 - 20.4
||26.8 - 32.7
|Eugenol (Oil of cloves) - 30.8
|Guaiacol (Petrochemical) - 32.7
|Lignin (Paper waste) - 27.4
The key point is that the ratio of 13C/12C in
vanilla extract from vanilla pods is significantly lower than vanillin
from all other sources.
The term natural is sometimes applied
to vanilla flavouring made from paper waste, as the starting material
(trees) is "natural" and renewable. Vanillin cannot be made
by this method without the use of chemical processing, however.