MULTI ELEMENT STABLE ISOTOPE ANALYSES FOR FRUIT JUICE GEOGRAPHICAL ORIGIN ANDPRODUCTION CONTROL

摘要

Premium products of fruit juice with defined origin and quality attain higher prices, but this is a temptation for unscrupulous producers or traders to sell cheaper or standard products as premium ones. Classical methods for quality control have beensupplemented successfully in the past 20 years by isotope ratio determinations, preferably of the elements hydrogen, carbon and oxygen, standing mainly for characterization of local climate and precipitation. In recent times this potential has been enlarged by the integration of the isotope ratio analyses on sulphur and nitrogen as indicators for geographical origin and for the applied farming or production methods, respectively, on a sample. In the present contribution this is demonstrated exemplarilyfor orange juices from various origins. Multi element isotope ratio analyses, mainly on pulp, are practized throughout. Already two-dimensional displays of the samples 13C and 345 values permitted their assignment to the geographical origin, the integration of the 15N values to assign them to conventional and organic farming, respectively Adulteration of natural red orange juice (not from concentrate) samples with orange cells could be identified by the comparison of the 34S and the N values of pulp andcells.