Gilles G. Martin

Improved detection of sugar addition to apple juices and concentrates using internal standard 13C IRMS

Abstract In order to improve the detection of sugar addition in apple juice using isotopic methods, malic acid has been defined as a suitable internal standard for the determination of the carbon 13 content. After a clean-up step, sugars and organic acids were separated from each other by an anion exchange process, and pure malic acid was isolated by preparative reversed-phase liquid chromatography (LC). This method has been applied to the stable isotope analysis of apple juice samples of different origins and years. A correlation between the carbon isotope ratios of sugars and malic acid has been observed, and cutoff points concerning the difference of δ 13 C values between those metabolites have been defined. In the case of the addition of sugar from C4 plants (such as corn and cane), it has been demonstrated that the detection limit can be as low as 5% whereas it is often higher than 10% while using the conventional carbon 13 method on the whole juice.

Authentication of natural flavours using SNIF-NMR® new developments on mustard oil and safron

Abstract In several industrialised countries, worldwide, “natural” food enjoys a growing success. Following this trend Flavour manufactures strive to provide natural flavours and essential oils to their customers in the food and beverages industry. Unfortunately, it has frequently occurred that chemically produced (nature-identical) molecules have been used (often unknowingly) without declaration as cheaper substitutes for natural flavours. A wide range of methods have therefore been developed to check the natural origin of many molecules constituting flavours. Among these techniques, Isotopic Methods (13C, 2H, 14C) occupy a prime position. Unfortunately, it has been reported that the most commonly used methods (14C counting and 13C SIRA analyses) can be easily countered by adulterators by addition of isotopically enriched compounds. The SNIF-NMR® method which provides isotopic ratios for each molecular position within a molecule has more recently been proposed as an uncounterfeitable fingerprint of natural molecules. Initially applied to ethanol, anethole and vanillin the SNIF-NMR® method has more recently been applied to a wide range of other natural molecules. This presentation will present sensitivity improvements of the SNIF-NMR® method for important molecules as well as new developments on safron and mustard oil.