Multi-element (H, C, N, O) stable isotope characterization of blueberries

For more than 20 years, the stable isotope ratios of bio-elements (hydrogen, carbon, nitrogen, oxygen) have been applied to food authenticity control for several commodities (fruit juices, honey, wine, spirits and flavorings). The objective of this study was to determine the capability of the isotopic analysis to characterize the geographical origin of soft fruits. About 40 samples of highbush blueberries (Vaccinium corymbosum L.) produced in the northern Italian region of Trentino and at two sites in Romania and Poland were collected and analyzed. The samples were measured for 18O/16O ratios of juice, and the 13C/12C and 15N/14N of pulp using Isotopic Ratio Mass Spectrometry (IRMS). For some samples, the 13C/12C of sugar and acid fractions using IRMS, and the D/H of fermented alcohol using site specific natural isotopic fractionation – nuclear magnetic resonance (SNIF-NMR) were also determined. Highbush blueberry showed typical stable isotopic ratios when compared with other soft fruits, particularly regarding the difference between the delta;13C values of acids. The berries from Trentino showed significantly higher delta;13C values of pulp as compared to the berries from Poland and Romania and significantly lower delta15N values than the Romanian product.