Isoscapes of carbon and oxygen stable isotope compositions in tracing authenticity and geographical origin of Italian extra-virgin olive oils

The authentication and verification of the geographical origin of food commodities are important topics in the food sector. This study shows the spatial variability in δ13C and δ18O of 387 samples of Italian extra-virgin olive oil (EVOO) collected from 2009 to 2011. EVOOs' δ13C and δ18O values were related to GIS (Geographic Information System) layers of source water δ18O and climate data (mean monthly temperature and precipitation, altitude, xerothermic index) to evaluate the impact of the most significant large-scale drivers for the isotopic composition of Italian EVOOs. A geospatial model of δ18O and δ13C was developed for the authentication and verification of the geographical origin of EVOOs. The geospatial model identified EVOOs from four distinct areas: north, south-central Tyrrhenian, central Adriatic and islands, highlighting the zonation of the expected isotopic signatures. This geospatial approach can be used to define a protocol for analyzing the isotopic composition of EVOOs in order to certify their origin and prevent food fraud. Limits and perspectives of the model are discussed.