Handbook of Vanilla Science and Technology

Ethyl Hexanoate | ― | 0.96116 | 0.11165 | 0.37054 | —0.0442

Guaiacol | ― | 0.0023 | 0.5506 | 0.01162 | 0.80818

Hexanal diethyl acetal | ― | 0.97141 | 0.23478 | 0.47905 | 0.03083

Ethyl Octanoate | ― | 0.64018 | 0.51133 | 0.54316 | —0.03314

Nonanoic acid | ― | 0.58698 | 0.64114 | 0.36559 | 0.67612

Ethyl Nonanoate | ― | 0.97227 | 0.38472 | 0.5459 | 0.15428

4-Ethoxymethyl phenol | ― | 0.40717 | 0.92058 | 0.49555 | 0.13943

4-Ethoxy-3-methoxybenzaldehyde | 0.14387 | 0.89371 | 0.17131 | 0.40043

Factor analysis could explain 75% of the variability with 3 factors and 4 factors could describe 86% of the variability. Discriminate analysis was also used to predict sensory quality with selected chromatographic components. The best resulting formulae correctly predicted 92% of the 55 vanilla extracts as acceptable compared to the sensory panel. A validation model was successfully performed with a separate set of 11 vanilla extracts.

Perez-Silva et al. (2006) provided further evidence as to the importance of chemicals other than vanillin to the complexity of the aroma of vanilla extract. They compared the aroma of several solvent extracts to that of vanilla powder prepared from ground beans from the Tuxtepec region of Mexico with sensory panels. The extracts were analyzed by GC-FID and GC-MS. They concluded that the pentane/ether extract correlated well with the panel evaluation for several chemicals at the ppm level. Guaiacol, 4-methylguaiacol, acetovanil-lone, and vanillyl alcohol had a major contribution to the aroma, even though they were present at levels 1,000 times lower than vanillin. Such studies verify the contribution to the aroma of components that are typically measured for vanilla quality and authenticity assessment, but also indicate that other, sometimes minor components, contribute to the sensory properties (Table 10.4). Thus, while chemists seek to measure components that attest to “quality” and authenticity, they also seek to measure components that validate the aroma and flavor quality of vanilla extracts.

Table 10.4 Aroma-active compounds detected by GC-O analysis of a representative aroma extract from cured vanilla beans. (Reproduced from Perez-Silva et al. (2006), with permission from Elsevier.)

Compounds | ppm | Odor quality | Intensity[4]

Phenols

Guaiacol | 9.3 | Chemical, sweet spicy | +++

4-Methylguaiacol | 3.8 | Sweet, woody | +++

p-Cresol | 2.6 | Balsamic, woody, spicy | ++

4-Vinylguaiacol | 1.2 | Chemical, phenolic | +

4-Vinylphenol | 1.8 | Sweet, woody | ++

Vanillin | 19118 | Vanilla, sweet | +++

Acetovanillone | 13.7 | Vanilla, sweet, honey | +++

Vanillyl alcohol | 83.8 | Vanilla-like | +++

p-Hydroxybenzaldehyde | 873 | Vanilla-like, biscuit | ++

p-Hydroxybenzyl alcohol | 65.1 | Vanilla-like, sweet | ++

Aliphatic acids

Acetic acid | 124 | Sour, vinegar | ++

Isobutyric acid | 1.7 | Buttery | ++

Butyric acid | <1 | Buttery, oily | +

Isovaleric | 3.8 | Buttery, oily | ++

Valeric acid | 1.5 | Cheese | +++

Alcohols

2,3-Butanediol (isomer 2) | 8.0 | Floral, oily | +

Anisyl alcohol | 2.4 | Herbal | ++

Aldehyde

2-Heptenal | 2.1 | Green, oily | +

(E)-2-decenal | 1.8 | Herb-like, floral | ++

(E,Z)-2,4-decadienal | 1.4 | Herb-like, fresh | ++

(E,E)-2,4-decadienal | 1.2 | Fatty, wood | ++

Esters

Methyl salicylate | <1 | Chalk | +++

Methyl cinnamate | 1.1 | Sweet | ++

Ethyl linolenate | 13.5 | Sweet | ++

Ketone

3-Hydroxy-2-butanone | 14.6 | Buttery | +

Unknown[5] | 6.2 | vanilla-like, chemical | +++

10.5 CONCLUSION

Vanilla continues to be the world’s most favored flavoring ingredient, with broad appeal and application. Over the last several decades, sophisticated research continued to unlock the secrets of this complex flavor. It is well established that the main constituent, vanillin, while playing a significant role, contributes less than one-third of the overall flavor/aroma impact. Researchers, such as Perez-Silva et al. (2006), with GC-MS and GC-O, were able to identify 26 odor active constituents, many at parts per million concentrations but still providing a sensory impact. Many other researchers, actively applying state of the art technologies, identified many constituents as well as compounds for the first time in vanilla. However, as researchers in the past, they were more interested in identifying new compounds and not in determining or reporting their contribution to the flavor of vanilla. These analytical data do contribute to the overall understanding of the constituents in vanilla and therefore can be used to maintain and improve the quality of this unique product.