Stable Isotope Fractionation in Fruit Juice Concentrates: Application to the Authentication of Grape and Orange Products

The thermokinetic fractionation coefficients of ²H and ¹⁸O in water of orange and grape juices were determined in experiments modeling the low-temperature evaporation processes carried out by agroindustries to concentrate fruit juices. These results can be used to refine the isotopic methods developed to control the adulteration of orange juices by sucrose and the concentration of musts to enrich wines. From the determination of the Brix value and the δ²H and δ¹⁸O isotope ratios of the remaining water of an orange concentrate, it is possible to infer the initial values of δ²H and δ¹⁸O in the pure juice. Knowledge of these parameters enables the detection level of sugar addition in the concentrate to be lowered. Conversely, by modeling the isotope fractionation processes that take place during must concentration, it is possible to use the δ²H and δ¹⁸O isotope ratios of wine water to improve the detection of wine enrichment by both sucrose addition and must concentration.