Geographical origin authentication of onions using stable isotope ratio and compositions of C, H, O, N, and S

Both stable isotope ratio and content of carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and sulfur (S) were employed to evaluate the possibility of geographical origin discrimination for onions grown in different regions in Korea. Significantly different elemental compositions were found in H, N, and S compositions, which might be related to different agricultural practices. The stable isotope ratio of C, H, O, N, and S was significantly different among classified regional groups. A linear discriminant analysis relatively well discriminated onions produced from different regional groups based on stable isotope and elemental composition data. Better discrimination of geographical origin of onions was achieved by combining groups located at similar latitude. Inclusion of the ratio of elemental compositions such as H/C and C/N improved the discriminative power for determining geographical origin of onions. Further distinct geographical differentiation of onion origin can be achieved by additional multi-elemental analysis.