Sr isotope composition of Golden Delicious apples in Northern Italy reflects the soil 87Sr/86Sr ratio of the cultivation area

Abstract

Background Apples have a leading role in the Italian fruit sector and high‐quality apples, including the Golden Delicious variety, are cultivated mainly in the Northern mountain districts. With this study, Golden Delicious apples from PDO (Protected Designation of Origin) and PGI (Protected Geographical Indication) cultivation districts were characterized according to their Sr isotope composition and compared to apples from other Northern Italian districts. Results Apples collected in two consecutive years (2017 and 2018) confirmed the low annual variability of the ⁸⁷Sr/⁸⁶Sr ratio. The isotope ratio of apples was highly correlated to that of the soil extracts of the respective orchards. Statistical differences were highlighted between cultivation districts. However, since similar geological features characterized some areas, their ratios overlapped and a complete separation of the districts was not possible. Conclusion The ⁸⁷Sr/⁸⁶Sr ratio is an excellent marker for studies of food traceability, as it retains the information about the place of origin. However, its strength is limited comparing products from cultivation areas sharing similar geological features. In the perspective of geographical traceability, a multi‐chemical characterization can overcome the limits of single‐parameter approach.