Handbook of Vanilla Science and Technology

Vanilla was introduced to Europe by the Spanish Conquistadores in 1520 but commercial production of vanilla started about 300 hundred years later with the discovery of hand pollination of the vanilla flower. In the wild, insects carry out the pollination of vanilla flowers (Childers et al. 1959). In commerce, vanilla is cultivated in tropical regions and is propagated by cuttings. The plant requires 3 to 4 years to set the flower, and afterward flowers once a year. The pod-like fruit (vanilla bean) is allowed to develop for 8 to 10 months before harvesting.

Vanilla beans are harvested green and are initially flavorless. The green beans are subjected to a curing process for 3 to 6 months or longer, depending on various curing protocols in different production regions. The objective of the curing process is to develop the prized vanilla flavor and to dry the cured beans to prevent microbial growth during transport and storage. Vanilla cultivation, vanillin biosynthesis, and economic aspects are discussed extensively in other reviews (Havkin-Frenkel et al. 2004, 2005). These reports provide a wealth of information on the botany of the vanilla bean, including detailed descriptions of special papillary cells that are believed to be the site of vanillin biosynthesis. This information is vital to the understanding of the curing process and for further improvement of this process. The curing process is described in detail in Chapter 6 by Frenkel et al.

In the United States, vanilla is the only flavor that has its own standard of identity, which defines how it is produced and labeled. For more details, see section21 CFR 169.175 oftheUS Code of Federal Regulations. V. planifolia and V. tahitensis are the only two Vanilla species allowed to be used in food. The beans need to be properly cured, with no more than 25% moisture content. A one-fold vanilla extract is defined as the total of flavor and odor principles of 13 oz of beans per gallon of water and alcohol. Alcohol content should be at a minimum of 35% by volume. Additional ingredients also permitted are glycerin, propylene glycol, sugar, and corn syrup. Vanilla flavors are vanilla extracts that contain less than 35% alcohol.

The authors’ research group has been collecting and analyzing vanilla, chiefly in the form of cured vanilla beans produced in different geographic regions, for over 20 years. Other investigators have focused their analytical efforts on vanilla extract rather than cured beans. The list of volatile and semi-volatile compounds detected in vanilla and/or vanilla beans is at least 494 and growing. Back in 1993, investigators in the authors’ lab at Rutgers University reported on volatile compounds in vanilla beans grown in Madagascar, Tahiti, Indonesia, Mexico, Tonga, Costa Rica, and Jamaica (Adedeji etal. 1993; Adedeji 1993). Since this time, vanilla cultivation has spread to some new regions, including India, Papua New Guinea, and Uganda. Our lab has more recently conducted studies of vanilla beans produced in the 2004 and 2005 growing seasons from a wide range of geographic regions. Some of the compounds detected in these analyses are reported in this chapter for the first time.

This chapter is a compilation of volatile/semi-volatile compounds detected in vanilla, as reported in the published literature. Table 11.1 is a list of volatile and semi-volatile compounds reported to be naturally present in vanilla. For the purposes of this chapter, vanilla is defined as vanilla beans and/or extracts prepared thereof. Compounds are listed in alphabetical order and are grouped by chemical class. For each entry, the individual compounds are listed using International Union of Pure and Applied Chemistry (IUPAC) nomenclature, common name or synonym, Chemical Abstracts Services Registry Number if available (CAS), and their reported concentrations (if available) in vanilla beans/vanilla extract from different vanilla species and geographic origins. The table also provides references to the original investigators. Please note that many volatile compounds occurring in vanilla and listed in the table do not contribute significantly to flavor or aroma. For instance, many of the compounds (i.e. hydrocarbons, long chain fatty acids, etc.) are odorless and have no flavor or aroma value. Entries highlighted in bold font in Table 11.1 are volatile compounds reported by the authors in this chapter for the first time.