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. In the present 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 with 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 with that of the soil extracts of the respective orchards. Statistical differences were highlighted between cultivation districts. However, because 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 because it retains the information about the place of origin. However, its strength is limited when comparing products from cultivation areas sharing similar geological features. In the perspective of geographical traceability, a multichemical characterization can overcome the limits of single‐parameter approach. © 2020 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Multi‐chemical analysis combined with chemometrics to characterize PDO and PGI Italian apples

“…Site description and sampling procedure are reported in detail in a previous paper. 32 Briefly, apples (cv. Golden Delicious, rootstock M9) were collected from orchards within the protected areas for the cultivation of ‘Mela Val di Non PDO’ (six orchards), ‘Mela Alto Adige PGI’ (17 orchards from three main cultivation districts, namely Bressanone, Val d'Adige, Val Venosta), ‘Mela di Valtellina PGI’ (three orchards), in addition to other cultivation areas located in northern Italy where apples with no geographical indication (GI) are produced (13 orchards) (Fig.…”

“…Apple sample preparation and analysis to determine the Sr isotope ratio was comprehensively described in a previous paper. 32 Briefly, all the digested samples went through a Sr/matrix separation to isolate the Sr fraction and remove the elements that potentially interfere with the Sr isotope ratio analysis, specifically Ca and Rb. Then, the 87 Sr/ 86 Sr was measured with a double‐focusing multicollector inductively coupled plasma mass spectrometer (Neptune Plus™, Thermo Scientific, Bremen, Germany) in dry‐plasma conditions (CETAC Aridus apparatus as aerosol drying unit and Jet sample cone + Ni ‘H’ skimmer cone).…”

“…Details about instrument configuration, operating conditions, data corrections and about the performance of the analysis are reported in previous studies. 32 , 39 …”

“… 26 , 27 , 28 Its high potential as soil‐derived traceability marker to distinguish different types of horticultural products according to their origin has been demonstrated in several studies. 29 , 30 , 31 , 32 …”

Identifying Counterfeit Cigarettes Using Environmental Pollen Analysis: An Improved Procedure*

“…Elemental isotope analysis combined with chemometrics data treatment using strategies such as principal component analysis (PCA) is a widely accepted method for verification of the geographical origin of a sample of interest. It has been used for tracing the origin of high-value meat (5) produce (6,7), rice (8), dairy product (9), wine (10), olive oil (11) etc. Stable isotopes were employed for forensic science studies with applications to both natural and manufactured products.…”