Tracing Strawberry Authenticity Using Isotope and Multielement Analysis

With increasing food demand, ensuring authenticity and traceability is crucial. Advanced analytical methods now reliably verify food origin, production, and composition. For strawberries, which are commonly consumed fresh and processed, techniques like stable isotope ratio analysis (EA-IRMS) and multielement analysis (ICP-MS) provide valuable tools to assess authenticity and geographic origin.

This study aimed to evaluate the potential of isotope and elemental profiling for differentiating strawberry varieties and geographic origins. A total of 40 fresh strawberry samples were analysed: from continental Croatia (Zagreb County), southern Croatia (Opuzen), unspecified domestic sources, and one from Italy. EA-IRMS was applied to determine ¹³C/¹²C and ¹⁵N/¹⁴N isotope ratios, while ICP-MS was used to quantify 21 elements (B, Na, Mg, Al, K, Ca, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, Cd, Ba, and Pb).

The results indicate that δ¹³C values were influenced by both variety and region. The Clery variety dominated in both continental (–25.4‰ to –26.6‰) and southern Croatia (–25.0‰ to –26.7‰), while less common varieties (Joly, Asia) showed similar values. Unidentified varieties ranged from –24.2‰ to –26.0‰. The Italian Aprica variety showed a value of –26.6‰. The δ¹⁵N values ranged from 2.15‰ to 9.82‰, reflecting different fertilisation regimes, with near-zero values suggesting organic cultivation.

Elemental profiles varied regionally: calcium levels differed across samples; strawberries from southern Croatia showed significantly higher magnesium content; and sodium concentrations were elevated in samples from southern Croatia, other continental areas, and Italy compared to Zagreb County.

These findings represent an initial step toward developing a reference database to support the verification of strawberry origin and strengthen food authenticity and traceability frameworks.

Acknowledgement: This work was carried out within the project "Food Safety and Quality Center" (KK.01.1.1.02.0004). The project is co-financed by the European Union from the European Regional Development Fund.