Bulk and Compound-Specific Stable Isotope Analysis for the Authentication of Walnuts () Origins.

Walnuts are grown in various countries, and as product origin information is becoming more important to consumers, new techniques to differentiate walnut geographical authenticity are needed. We conducted bulk stable isotope analysis (BSIA) and compound-specific stable isotope analysis (CSIA) on walnuts grown in seven countries. The BSIA consisted of δC, δN, and δS, and CSIA covered δH, δC, δC, δN, and δH.