Recent applications of stable isotope ratio analysis in the study of wine and wine products

Traceability can verify some sustainability claims about commodities and products, such as the geographical origin of raw materials, helping to fight counterfeits and to ensure the respect for people and environment in the supply chains. In the last decays, to allow an effective traceability, several analytical techniques have been proposed, including the stable isotopes analysis of the major bio elements (SIRA) and the quantification of minor tracers. Based on the measurement of the ratio between the heaviest and the lightest isotope of an element (such as carbon or oxygen), SIRA has proved to be an effective technique for the traceability and the authentication of wine [1-3] and wine products [4,5]. Recently, new methods based on this technique have been developed. A liquid chromatographer coupled with an isotope ratio mass spectrometer (LC-co-IRMS), measuring the carbon isotopic ratio (δ13C) of the major sugars of Italian musts, made it possible to detect fraudulent addition of exogenous glucose and fructose deriving from C4 plants and to characterise the product based on its geographical origin [6]. Furthermore, a recent study based on the use of a continuous-flow isotope ratio mass spectrometer (CF-IRMS) GasBench II (Thermo Fisher Sci, Bremen, Germany) allowed to improve the analysis of the oxygen isotopic ratio (δ18O) of wine, must, vinegar and balsamic vinegar by optimising analytical conditions such as temperature and run duration. The improvement of the working condition results in a more efficient analytical procedure, helping in the reduction of analysis time and waste. Finally, new tracers like polyalcohols (e.g., myo-inositol and scyllo-inositol) or minor sugars (e.g., lactose) characteristic of grape must, have been recently used to detect the fraudulent addition of sugar syrups to concentrated musts. To this purpose, 450 authentic Italian grape musts of different varieties and coming from different Italian regions have been considered [7].