Handbook of Vanilla Science and Technology

Vanilla is an extremely unique product and not only because it is the only orchid which produces an edible product. This tropical vine has limited production and is found only in countries within 15 to 20 degrees above and below the equator. The two main cultivated species are Vanilla planifolia and V. tahitensis. In the United States, these are the only species permitted to be used in food products. The vanilla plant requires years in order to mature to fruit bearing. The plant then requires 6 to 9 months to produce vanilla beans, which requires a unique hand pollination of the flower, which is open for only a few hours. Once the mature green beans are harvested, processing and curing the beans is an intensive hands-on process designed to produce a flavorful product. Several rapid, controlled curing processes have been developed, but most curing is still manual. During the mid-1900s, many beans were stored for up to 3 years, continuing the development of more flavor constituents. However, this later storage stage was virtually discontinued during government unrest in a major producer, Madagascar, during the 1970s and 1980s. All the stored stocks were sold. Now most commercial vanilla beans are annually produced and sold. A very detailed description of vanilla horticulture and curing is found in Gillette and Hoffman (2000).

The cured beans can be sold as they are, but the vast majority is used to produce vanilla extract. Extraction is also an intensive process requiring multiple aqueous alcoholic washes, which can be achieved by a variety of methods. The one-fold extract (1 x) can be sold or concentrated to multifold 2x,31/3x,5x,10x,20x, and even 26 x. The latter is an oleoresin with little to no residual solvent. The vanilla extract fold is regulated in the United States by the US Code of Federal Regulations (21CFR169.175). This regulation, considered the “standard of identity”, defines a “unit” of vanilla beans as 13.35 ounces of beans of not more than 25% moisture in one gallon of aqueous ethanol at not less than 35%. The standard describes folds, labeling, and other products. More detail on the manufacture of vanilla, as well as the regulation of this product, can be found in Gillette and Hoffman (2000) and in the chapter in this book by Ranadive.

Because of the limited origins and the intensive and complex production sequence from plantation to store shelf, there are many financial incentives to short-cut this process at many points. In addition, one of the major producing countries, Indonesia, has an intensive population, in excess of 230 million in a country slightly smaller than Texas. These factors encouraged pilfering of beans maturing on the vine and early harvesting by many farmers in order to prevent this loss. These early picked beans, even if cured correctly, lack many of the necessary precursors for the production of the unique flavor constituents, as well as reduced amounts of others. Also, the proper, substantial, and costly curing process can also be quickened or shortened, again producing a less flavorful and lower quality product. Furthermore, the high cost of quality beans encourages extension and dilution of these extracts. And finally, while fully imitation products, if properly labeled, are perfectly acceptable and in some instances a close approximation of the “real thing”, there are those unscrupulous suppliers that sell these as “pure product”.

Since the discovery and use of this product, it has been extensively analyzed in order to understand the origin of this unique and desirable flavor. In addition, it has been analyzed in order to assure that the vanilla’s quality is maintained and to assure the consumer that the product is indeed “real” vanilla. The early wet chemistry techniques used to identify the major flavor constituents, as well as to affirm authenticity, included painstaking extraction, isolation, and purification, resin determination, paper and thin layer chromatography, or other methods (Gillette and Hoffman, 2000 and references therein). As new analytical techniques were developed, so did the application of these methods to understanding the flavor of vanilla as well as to detecting adulterated products. These methods range from the chromatographic techniques such as gas chromatography (GC) and high performance liquid chromatography (HPLC), to the most recent nuclear magnetic resonance (NMR) and accelerator mass spectrometer (AMS) instrumental techniques. Also, new sophisticated isolation techniques beyond solvent/solvent extraction were developed and applied to vanilla. Supercritical CO₂ extraction, solid phase micro extraction (SPME), and stir-bar sorptive extraction (SBSE) are examples.

10.2 VANILLA FLAVOR ANALYSES