Stable Isotopes as a Predictor for Organic or Conventional Classification of Berries and Vegetables

Abstract As organic agriculture spreads globally, promising enhanced food quality and soil health, the challenge lies in verifying the authenticity of organic practices, notably in developing countries with limited oversight. This study offers a solution by examining the elemental composition of carbon (C) and nitrogen (N), particularly their stable isotopes (δ¹³C and δ¹⁵N), in seven crops grown under organic or conventional methods across various countries. Our findings reveal that, while total C and N content showed no significant differences across production methods or regions, the N stable isotope (δ¹⁵N) levels were markedly distinct between organic and conventional crops. This difference allows us to propose a δ¹⁵N threshold to reliably distinguish between organic and conventional raspberries and strawberries, with a very low error rate. These thresholds, backed by an extensive dataset (n=791), hold promise as effective tools for confirming organic authenticity, providing a new standard for future validation of organic farming practices.