Handbook of Vanilla Science and Technology

We recently analyzed some cured, wild vanilla beans collected from a Peruvian rainforest. The beans are of unknown species but morphologically they resembled V. odorata. Interestingly, the beans were found to contain a novel series of anisyl alcohol esters that have not been described previously as occurring in vanilla, or any other natural products for that matter. In addition to anisyl formate, anisyl acetate, anisaldehyde, and anisic acid, which have been reported previously in vanilla, the compounds anisyl acrylate, anisyl salicylate, anisyl anisate, anisyl vanillate, anisyl protocatechuate, anisyl myristate, anisyl pentadecanoate, anisyl palmitate, anisyl linoleate, anisyl oleate, anisyl linoleate, and approximately 10 unidentified anisyl alcohol esters were found. We believe that this data further supports the hypothesis that V. tahitensis appears to be a hybrid of V. planifolia and V. odorata, based on the nuclear and plastid DNA sequence analysis recently reported by Lubinsky et al. (2008). It is well known that V. tahitensis beans have a floral/perfume nuance imparted by high concentrations of anisalde-hyde, anisyl alcohol, anisic acid, and anisyl esters that are found at much lower concentration or not at all in V. planifolia. In contrast, the putative V. odorata beans are very high in anisyl alcohol derivatives and it stands to reason that interspecific hybridization of V. planifolia and V. odorata may be responsible for the genetic basis of anisyl traits in V. tahitensis.

In addition to the compounds listed in Table 11.1, which are assumed to be naturally occurring in vanilla, analyses often reveal synthetic compounds as common contaminants and/ or adulterants. Many of these compounds are packaging-borne migrants. For instance, vanilla beans are often bundled and shrink-wrapped in polyvinyl chloride (PVC) films. Synthetic plasticizers, stabilizers, and antioxidants present in these films migrate into the beans and are commonly detected. Plasticizers such as diethylphthalate (DEP), dibutylphthalate (DBP), di-2-ethylhexylphthalate (DEHP), butyl, benzyl phthalate (BBP), diisononylphthalate (DINP), diisodecylphthalate (DIDP), dibutyladipate (DBA), dioctyladipate (DOA), tributylphosphate (TBP), tributyl, acetyl citrate (Citroflex A), and many others are commonly found. Synthetic hindered phenol-type antioxidants such as butylated hydroxyl toluene (BHT) are ubiquitous in vanilla beans that we have analyzed.

Table 11.1 Volatile compounds detected in vanilla beans from different species and from different geographic growing regions. The concentrations reported are in ppm and the references are indicated by superscripts

^aAdedeji et al. 1993

^bPerez-Silva et al. 2006

^cDaCosta and Pantini 2006

^dWerkhoff and Guntert 1996

^eGaletto and Hoffman 1978

^fHartman et al.1992

^gKlimes and Lamparsky 1976

^hLee 2006

ⁱShiota and Itoga 1975

^jPrat and Subitte 1969

^kLhugenot et al. 1971

^lAnwar 1963

^mBohnsack 1965

ⁿBohnsack and Seibert 1965

^oBohnsack 1967

^pBohnsack 1971a

^qBohnsack 1971b

^rChovin, et al. 1954

^sGnadinger 1925

^tStoll and Prat 1960

^uSimony 1953

^vBonnet 1968

^wPritzer and Jungkunz 1928

^xWalbaum 1909

yTiermann and Haarmann 1876

^zBusse 1900

^aaKleinert 1963

^abMorison-Smith 1964

^acCowley 1973

^adGoris 1924

^aeGoris 1947

^afChevalier et al. 1972

^agSchulte-Elte et al. 1978

The high cost of vanilla has historically led to adulteration by unscrupulous merchants eager to gain an economic advantage. The practice is widespread enough to have generated elaborate analysis methods to detect adulteration (i.e. isotope ratio mass spectrometry, stable isotope fractionation, nuclear magnetic resonance spectroscopy, etc.) and has been addressed by special committees of the American Chemical Society (ACS), industry groups such as the US Flavor and Extracts Manufacturers Association (FEMA), and many others worldwide. Most of these methods are focused on detection of adulteration based on “boosting” vanillin concentration in vanilla beans or extract by adding synthetic vanillin. However, our group has also observed a less obvious method of adulteration that involves spraying vanilla beans with compounds to increase their weight. Compounds such as glycerol, 1,3-butylene glycol, and others are naturally occurring in vanilla beans to some extent but can be sprayed on beans to increase their weight and thus the price paid per unit weight basis. Beans with unusually high concentrations of these type glycols/polyols should be considered suspect.