Isotopic and Elemental Analysis of Apple and Orange Juice by Isotope Ratio Mass Spectrometry (IRMS) and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS)

Twenty-five samples, consisting of 15 commercial juices and 10 directly pressed orange and apple juice samples were analyzed by isotope ratio mass spectrometry (IRMS) and inductively coupled plasma - mass spectrometry (ICP-MS). The isotopic results showed that most of the commercial fruit juices were made from concentrate by re-dilution with water and five of investigated juices contain C4 sugars from corn or cane sugar. The differences between the concentrations of macronutrients in the juice samples indicate that the mineral fertilization, soil characteristics, and the addition of preservatives or adulterants, influence the quality and nutritional values of the product. In order to extract the most meaningful information and to highlight the influence upon the analytical results obtained from the IRMS and ICP-MS measurements, linear discriminant analysis (LDA) was used. delta C-13, Ni, Cr, Ca, Sr, Fe, K, Mg and Na were shown to be the best markers for the differentiation of orange from apple juice. Also, the best predictors for the discrimination of commercial from directly pressed juice were delta O-18, K and Na.