Strontium isotopes as geological fingerprints in potatoes cultivated on ocean-island basalts

Food fraud related to the geographical origin of high-value agricultural products represents a persistent challenge in regions where local production coexists with large volumes of imported material. In the Canary Islands, potatoes constitute a culturally and economically important crop, with locally grown and traditional cultivars commanding substantially higher market prices than imported varieties, creating clear incentives for mislabelling. 

Strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) represent a metal isotope system that directly links agricultural products to the geological and biogeochemical characteristics of their cultivation environment through soil–plant transfer processes. Applications to plant-based products grown under contrasting agronomic and water-management conditions demonstrate that geological substrates exert primary control on strontium isotopic signatures. Potatoes cultivated on Tenerife display tightly constrained ⁸⁷Sr/⁸⁶Sr ratios between ~0.7046 and ~0.7054, consistent with uptake from low-radiogenic ocean-island basalts characteristic of the island. 

These isotopic values are well separated from those typically associated with continental European agricultural regions and remain coherent across different potato cultivars, despite variability in strontium concentrations (≈410–710 ppb/g). Even within a single basaltic island, small but reproducible variations in ⁸⁷Sr/⁸⁶Sr are observed, reflecting local geological heterogeneity and soil development. 

The results highlight the suitability of strontium isotopes as a geology-driven fingerprint within terrestrial biogeoscience systems and demonstrate their potential for verifying the Canarian origin of potatoes. This approach provides a robust foundation for applied provenance studies and authenticity control in volcanic island agro-ecosystems.