THE USE OF ISOTOPE RATIOS IN COMMERCIAL FRUIT JUICES AUTHENTICATION

In this study, commercial fruit juices present on Romanian market were investigated, by mean of stable isotopes, in order to check their correct labeling. In order to detect the sugar addition, to investigated fruit juices, δ 13 C values of: whole juice, pulp and sugars were determined. Beside these, δ 18 O and δ 2 H values of fruit juices water were measured in order to differentiate directly press juices from juices obtained from concentrates by re-dilution. The interpretation of these results is based on the fact that authentic juices have elevated δ 18 O and δ 2 H content of water as compared to water from re-diluted products, which were made using tap water which is relatively, depleted in heavy oxygen and hydrogen isotopes.