A review of flavors authentication by position‐specific isotope analysis by nuclear magnetic resonance spectrometry: the example of vanillin

Abstract

Consumers are increasingly interested in the authenticity and traceability of food products. This review aims at describing the principles of NMR Position‐Specific Isotopic Analysis and the applications and perspectives for aroma‐chemical authentication. Vanillin is an excellent example since, owing to its organoleptic qualities; it is undoubtedly one of the most used aroma‐chemicals in food, confectionery, beverages, perfumery, cosmetics and pharmaceutical industries. 2H‐NMR was first used, but it required several hours of spectrometer time and fairly large sample amounts. 13C NMR enabled the reduction of both the experimental time and the needed quantity of vanillin. Recent developments will soon make the analysis of vanillin possible in manufactured products. Copyright © 2016 John Wiley & Sons, Ltd.

Combination of 13C and 2H SNIF‐NMR isotopic fingerprints of vanillin to control its precursors

“…The isotopic compositions for each site of the molecule of vanillin obtained by 2 H SNIF‐NMR were first studied to evaluate the discrimination power regarding the origins of the precursors . Then the isotope ratios obtained by 13 C SNIF‐NMR were evaluated in the same manner as the 2 H isotope ratios.…”

“…Adiabatic pulses were used for 1 H decoupling . The acquisition conditions were as follows, with no tube spinning: acquisition time, 1 s; spectral width, 200.4 ppm; number of scans adjusted to reach an SNR of 500, at a minimum, on the carbon site 5 at around 127 ppm (see numbering, Appendix S1); and with a fixed number of four dummy scans …”

“…Results obtained by 13 C SNIF‐NMR were expressed as isotopic composition by site in ‰ ( δ 13 C i ), as described during the inter‐laboratory study . The calculation did not use an internal reference, but deduced from the total 13 C/ 12 C ratio measured by EA‐IRMS as previously described . No correction factor for the instrument response was applied to obtain δ 13 C i on the absolute δ‐ scale; relative values were sufficient for chemometrics use.…”

“…In this context, this special issue dedicated to ‘authenticity’ also reflects this importance. Not surprisingly, most of the articles in this special issue are dedicated to the authenticity of vanilla, thus showing the prevailing interest in this flavor …”

Analytical contribution of deuterium 2D‐NMR in oriented media to 2H/1H isotopic characterization: the case of vanillin

“…). The toolkit for irm‐NMR has more recently been strengthened by the development of irm‐ 13 C 1D‐NMR, which accesses the carbon skeleton of the molecule, providing additional isotopic information to that obtained by natural abundance deuterium NMR (NAD NMR). All of the desired information, however, is not always accessible by the exploitation of these techniques alone.…”