Handbook of Vanilla Science and Technology

In order to distinguish between a pure vanilla extract and one to which synthetic vanillin has been added, Martin et al. (1977) developed an identification ratios method. They determined the absolute levels of vanillin, potassium, nitrogen, and phosphate in the authentic extracts made from beans from Madagascar, Mexico, Indonesia, Comoros, and Tahiti. Next, they determined the vanillin/K, vanillin/N, and vanillin/PO₄ ratios for each type of product (Table 9.6) and established that these ratios were different for different type of beans but fairly constant for authentic extracts made from same type of beans. Their work further established that when these ratios, for a particular vanilla extract, were considerably higher than the authentic vanilla extracts, it was a strong evidence of added vanillin. On the other hand, low absolute values for vanillin, K, N, and PO₄ in a vanilla extract were an indication of inadequate amounts of beans used.

Table 9.6 Ratios of vanillin and N, PO4, and K in authentic vanilla extracts

Vanillin/N[2] 11(M), 2.2 (J), 8 (MX), 7.5 (T)

Vanillin/PO4* 11.8 (M), 1.6(J), 8 (MX), 7.5 (T)

Vanillin/K* 1.5 (M), 0.25 (J), 1.45 (MX), 0.8 (T)

Vanillin/p-hydroxybenzaldehyde 12-15 (M,J,MX) 7.9 (T), 27(I)

9.4.1 Guidelines for determination of authenticity

Authenticity of vanilla products is now accepted if it conforms to criteria defined by: i) the US standard of identity for vanilla, and ii) IOFI (International Organization of the Flavor Industry) guidelines, which has adapted the French government’s document specifications titled DGCCRF (Directorate General for Competition, Consumption, and Fraud Repression).

The definition for the US standard of identity for vanilla has been given before. This requirement basically defines pure vanilla as a product made from only two species of vanilla, V. planifolia and V. tahitensis, using the specified amount of vanilla beans and containing at least 35% ethyl alcohol by volume.

IOFI Guidelines N 1271 has adopted three criteria to determine authenticity of natural vanilla products.

9.4.1.1 Evaluation of the ratios between specific components

There are four major components in vanilla, which are used as marker compounds to determine quality and authenticity of vanilla products. The specific components are p-hydroxybenzoic acid (p-HB acid), p-hydroxybenzaldehyde (p-HBAld), vanillic acid, and vanillin. These four components are easily separated and calculated by the HPLC method of analysis. For authentic vanilla extracts, these ratios are fixed within a certain range. The revised guidelines by DGCCRF - Notification note - 2003-61, and adopted by IOFI for these ratios are given in Table 9.7. However, the ratios for vanillin/p-HBAld (R1) and vanillic acid/ p-HBAld(R2) for Indian vanilla beans were found to be higher than the DGCCRF guideline by John and Jamin (2004) and Gassenmeier et al. (2008).

Table 9.7 DGCCRF Guideline values

Ratios between flavor components | Revised ranges

R1 = Vanillin/p-HBAld | 10-20

R2 = Vanillic acid/p-HBAld | 0.53-1.5

R3 = p-HB acid/p-HBAld | 0.15-0.35

R4 = Vanillin/Vanillic acid | 12-29

R5 = Vanillin/p-HB acid | 40-110

9.4.1.2 Isotope-ratios mass spectrometry

This guideline for authenticity verification involves the determination of the ¹³C deviation of each of the four important vanilla aromatics, vanillin, p-hydroxylbenzaldehyde (p-HB), p-hydroxybenzoic acid (p-HB acid), and vanillic acid.

DGCCRF- Notification note - 2003-61 has determined acceptable limits for ¹³C deviation values for four main components of vanilla. These values are given in Table 9.8. Excellent information on ¹³C deviations is available in Scharrer and Mosandl (2002) and John and Jamin (2004) (Table 9.8).

Table 9.8 ¹³C Deviation values

Vanillin | - 21.2%

p-Hydroxybenzaldehyde | - 19.2%

Vanillic Acid | - 24.0%

9.4.1.3 Site-specific quantitative deuterium NMR

This method depends on determining the authenticity of pure vanilla by determining the four site-specific natural isotope ratios (D/H) of its vanillin molecule (Figure 9.6) by NMR (Remaud et al. 1997).

9.4.2 Other methods to determine authenticity

9.4.2.1 SIRA-Stable Isotope Ratio Analysis