Detection of Sophisticated Adulterations of Natural Vanilla Flavors and Extracts: Application of the SNIF-NMR Method to Vanillin and p-Hydroxybenzaldehyde

Abstract

This paper describes recent progress in the isotopic analysis of the two main aromatic constituents of vanilla flavor (vanillin and p-hydroxybenzaldehyde (pHB)). Some improvements concerning the SNIF-NMR analysis of vanillin are presented. They include (i) improvement of the analytical precision by using new software for automatic phasing, baseline correction and curve fitting of the signals of the 2H-NMR spectra; (ii) significant enrichment of the database containing measurements performed on vanillin extracted from vanilla beans harvested in different countries and on synthetic vanillin; (iii) standardization of the purification process to obtain pure vanillin, in order to avoid isotopic fractionation; and (iv) improvement of the statistical tools for both proving and quantifying adulterations. All these improvements were also successfully applied to site specific deuterium NMR analysis of pHB. It is now also possible with the SNIF-NMR method to discriminate between the natural and chemical origins of p...