Compound-specific δ 13 C and δ 15 N analyses of fatty acids and amino acids for discrimination of organic, pesticide-free, and conventional rice (Oryza sativa L.).

Herein, we improve the procedure for organic rice authentication using compound-specific δ ¹³ C and δ ¹⁵ N analyses of fatty acids and amino acids, addressing the increasing demand for accurate methods to confirm organic authenticity. Organic rice (OR) and pesticide-free rice (PFR) featured higher values of δ ¹⁵ N _bulk than conventional rice (CR), whereas the corresponding differences between OR and PFR were insignificant. Additionally, OR, PFR, and CR could be discriminated based on some δ ¹³ C _amino-acid and δ ¹⁵ N _amino-acid values. δ ¹³ C _bulk was correlated with most δ ¹³ C _fatty-acid (r ≥ 0.596) values, and δ ¹⁵ N _bulk was strongly correlated with most δ ¹⁵ N _amino-acid (r ≥ 0.834) values. The first component in the orthogonal projection to latent structure-discriminant analysis model allowed for a clear separation between OR and PFR, and good predictability (Q ² Y = 0.506). Thus, the present study improves the reliability of organic authentication when bulk stable isotope ratio analysis alone is insufficient for the accurate discrimination of OR, PFR, and CR.
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