Handbook of Vanilla Science and Technology

Like the flavor analytical research, the biochemical research progressed significantly during these same 20 years. Significant research identified the flavor precursors for the major flavor constituents of vanilla, the phenolic glycosides, and demonstrated the formation of these flavor constituents through the action of b-glucosidase during curing. Vanilla browning during curing was also attributed to the enzyme polyphenol oxidase, which also decreases the vanillin content. In addition, genetic research demonstrated the relationships among the Vanilla spp. Also researchers were able to develop hybrids, which were resistant to Fusarium. All of these investigations can contribute to vanilla quality.

As technologies advanced flavor research and biotechnology, unfortunately they were also used by unscrupulous suppliers to take advantage of the limited supply of this costly product and circumvent existing authentication methods. In response, the legitimate flavor industry, regulators, and academics applied sophisticated technologies to thwart these dishonest suppliers. Liquid chromatographic techniques, including HPLC and HP-TLC, were enhanced and applied to vanilla authentication. The key vanilla constituents were separated and quantified by researchers around the world with a variety of liquid chromatographic techniques. Ratios of these constituents were determined and shown to be relatively consistent, regardless of researcher or origin of the vanilla. Unfortunately, these ratios were promulgated into national regulations but, because of the natural constituents involved, there were legitimate products that fell outside the limits set in regulations. However, the vanillin/p-hydroxybenzaldehyde ratio is the most consistent and should be used as an initial analysis, which if necessary, could be followed by the more accurate isotopic analysis.

Like all technologies, the isotopic methods evolved dramatically during this time. Radiocarbon analyses (¹⁴C), stable isotope ratio analysis (SIRA), nuclear magnetic resonance analysis (NMR), accelerator mass spectrometry AMS, and even gas proportional counting (GPC), were all updated, refined, and applied to authenticating vanilla products.

These techniques were also coupled with other technologies in order to enhance the detection of adulterated products, for example GC-C-IRMS and methods linking HPLC and SIRA.

Finally, recent research has linked minor flavor constituents to the overall vanilla flavor. Additional research in this area needs to be undertaken and reported.

REFERENCES

Adedeji, J., Hartman, T. and Ho, C. (1993) Flavor characterization of different varieties of vanilla beans. Perfumer & Flavorist, 18, 25-33.

Archer, A. (1989) Analysis of vanilla essences by high-performance liquid chromatography. Journal of Chromatography, 462, 461-466.

Avila, M., González, M.C., Zougagh, M., Escarpa, A. and Rios, A. (2007) Rapid sample screening method for authenticity controlling vanilla flavors using a CE microchip approach with electrochemical detection. Electrophoresis, 28, 4233-4239.

Belay, M.T. and Poole, C.F. (1993) Determination of vanillin and related flavor compounds in natural vanilla extracts and vanilla-flavored foods by thin layer chromatography and automated multiple development. Chromatographia, 37, 365-373.

Bensaid, F.F., Wietzerbin, K. and Martin, G. (2002) Authentication of natural vanilla flavorings: isotopic characterization using degradation of vanillin into guaiacol. Journal of Agricultural and Food Chemistry, 50, 6271-6275.

Bettazzi, F., Palchetti, I., Sisalli, S. and Mascini, M. (2006) A disposable electrochemical sensor for vanillin detection. Analytica Chimica Acta, 555, 134-138.

Brodelius, P.E. (1994) Phenylpropanoid metabolism in Vanilla planifolia Andr. (V) High performance liquid chromatographic analysis of phenolic glycosides and aglycons in developing fruits. Phytochemical Analysis, 5, 27-31.

Calabretti, A., Campisi, B., Procida, G., Vesnaver, R., and Gabrielli, L. (2005) Analysis of volatile compounds of Vanilla planifolia essential oil by using headspace soild-phase microextraction. Proceedings ofthe 2nd Central European Meeting [and] 5th Croatian Congress of Food Technologists, Biotechnologists and Nutritionists, Opatija, Croatia, October 17-20, 2004, pp. 249-257.

Charvet, A.S. and Derbesy, M. (2001) Vanilla beans analysis. Samples analyzed between January 1 and December 31, 2000. Annales des Falsifications de l’Expertise Chimique et Toxicologique, 94, 79-84.