One of the most common flavors used today is the flavor of vanilla. Look through the ingredients in your kitchen and read the label on your favorite ice cream, cookies, cakes, etc.; you will often find references to vanilla extract or artificial vanilla flavor (or imitation vanilla extract). Are these two terms synonymous? If not, how are the two materials they represent different?

We will show the differences in the definitions between vanilla extract and artificial vanilla flavor, and ask you to design and conduct a Virtual Mass Spectrometry Laboratory experiment to determine if a bottle of vanilla extract purchased from the local grocery store is authentic or not.

Vanillin is the trivial name of the chief flavoring compound in natural vanilla extract. It is also the major or exclusive chemical compound in artificial vanilla flavoring. Inspection of the Kekule structure of vanillin reveals its rather simple architecture. Given that the major flavoring compound in both vanilla extract and artificial vanilla flavor is vanillin, what is the difference between the two?

Producing Vanilla Extract

Vanilla extract is the solution obtained when one dissolves the extracts of 100g of vanilla beans in 1 liter of 45%, by volume, ethanol. {Sugar can be, and often is, added.}

Vanilla beans are harvested from the vanilla orchid (Vanilla planifolia), a tropical plan primarily cultivated in Mexico, Indonesia, and the Malagasy Republic. The bean, when harvested, contains very little vanillin (instead, the vanillin exists as a glucoside); however upon fermenting, the beans generate vanillin which often appears as white crystals on the surface of the bean. The vanillin is readily extracted from the fermented beans with aqueous-ethanol solutions.

Vanilla Pods

Vanilla Extract

As there are hundreds of additional organic compounds present in the beans, and soluble (to different extents) in aq-EtOH, vanilla extract contains principally vanillin but also several hundred additional components in trace amounts. (It is these additional complex mixtures that subtly distinguishes the flavor of vanilla extract from artificial vanilla flavor.)

In 1986 vanilla beans sold for $30-$38 per pound. To be most precise, a vanilla extract, as defined by a standard of the Food and Drug Administration, "is the solution, containing not less than 35% alcohol, of the sapid and odorous principles extracted from one or more units of vanilla consitutent. One unit of vanilla consituent is 13.35 oz of vanilla beans containing not more than 25% moisture in 1 gal of finished product. No addition of artificial vanillin is permitted in products designed as vanilla extract". (Martin, 1977)

Developing Imitation Extract

Imitation vanilla extract refers to an alcoholic solution containing synthetically derived vanillin. Thus the major flavoring agent in vanilla extract and imitation vanilla extract is identical; the differences are (1) synthetic vanillin is considerably cheaper than extracted vanillin, and (2) vanilla extract contains hundreds of trace components.

The cheapness of synthetic vanillin is due in part to the discovery, in the 1950s, that a waste product of the wood pulp industry, lignin, could be readily oxidized to vanillin. The source of abundant vanillin ensures this popular flavoring agent is widely available for food uses.

The source of abundant synthetic vanillin also presented food counterfeiters with a method of making a great deal of money fraudulently--simply by marketing the cheap synthetic vanillin as authentic vanilla extract. (This can take several forms ranging from complete substitution of the authentic material to a dilution of the authentic material by adding synthetic vanillin.)

The Problem

How is a regulatory agency such as the FDA to determine if the vanilla extract that you pay a substantial price for in the local grocery store is in fact authentic? Or, stated in another way, if you pay the premium price for the authentic vanilla extract, you don't want to receive a solution of only vanillin (Visit Spice Notes Vol. 1 for related information).

The solution in current practice is a direct reflection of the biosynthetic pathways leading to vanillin and lignin--these are substantially different. One consequence is that there are measurable differences in how efficiently the pathways allow a molecule containing a carbon-13 isotope to enter the pathway. The vanillin produced from the oxidation of lignin and the vanillin produced by the vanilla bean have a measurable difference in the C-12 to C-13 in their makeup (vanillin from the vanilla plant is slightly enriched in ¹³C relative to vanillin from wood pulp lignin). Thus, a mass spectrometry-based approach, Stable Isotope Ratio analysis (SIRA) has been developed that allow the two sources of vanillin to be distinguished.

The Future

The great use of vanillin ("the world's most important flavoring agent") ensures active work continues on all aspects of the molecule, including genetic engineering (see for instance: http://www.ifrn.bbsrc.ac.uk/BUSCOM/FOOD_INFO/vanillin.html.)

References:

"Determining the Authenticity of Vanilla Extracts", G.E. Martin, M.W. Ehtridge, and F.E. Kaiser, J. Food Science, 1977, 42, 1580-1586.

"Carbon Isotopes in Vanillin and the Detection of Falsified "Natural" Vanillin", D.A. Krueger and H.W. Krueger, J. Agric. Food Chem., 1983, 31, 1265-1268.

"Detection of Fraudulent Vanillin Labeled with ¹³C in the Carbonyl Carbon", D.A. Krueger and H.W. Krueger, J. Agric. Food Chem., 1985, 33, 323-325.

"Vanilla", C.H. Breedlove, ChemMatters, 1988, April, 8-.

"The Determination of Vanillin in Vanilla Extract", E.W. Ainscough and A.M. Brodie, J. Chem. Ed., 1990, 67, 1069-1071.

"Determination of the Authenticity of Vanilla Extracts by Stable Isotope Ratio Analysis and Component Analysis by HPLC", J. Agric. Food Chem., 1994, 42, 1722-1727.

"Vanillin: Synthetic Flavoring from Spent Sulfite Liquor", M.B. Hocking, J. Chem. Ed., 1997, 74, 1055-1059.