DETECTION OF SOPHISTICATED ADULTERATIONS OF NATURAL VANILLA FLAVORS AND EXTRACTS - APPLICATION OF THE SNIF-NMR METHOD TO VANILLIN AND P-HYDROXYBENZALDEHYDE

This paper describes recent progress in the isotopic analysis of the t wo main aromatic constituents of vanilla flavor (vanillin and p-hydrox ybenzaldehyde (PHB)). Some improvements concerning the SNIF-NMR analys is of vanillin are presented. They include (i) improvement of the anal ytical precision by using new software for automatic phasing, baseline correction and curve fitting of the signals of the H-2-NMR spectra; ( ii) significant enrichment of the database containing measurements per formed on vanillin extracted from vanilla beans harvested in different countries and on synthetic vanillin; (iii) standardization of the pur ification 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 als o successfully applied to site specific deuterium NMR analysis of pHB. It is now also possible with the SNIF-NMR method to discriminate betw een the natural and chemical origins of pHB. New results concerning th e delta(13)C deviation of pHB are also presented. Thus the lowest valu e of delta(13)C of pHB extracted from vanilla bean can be set at -19.5 parts per thousand. We recommend the methodology presented in this pa per as a standard procedure for purifying vanillin and pHB, without si gnificant isotopic fractionation, from most matrices (for example from ice cream, yogurts, etc.), in order to perform isotopic analyses (C-1 3 IRMS and H-2-NMR).