Analytical Sciences

Abstract − Analytical Sciences, 32(7), 781 (2016).

Tracing the Geographical Origin of Onions by Strontium Isotope Ratio and Strontium Content
Hisaaki HIRAOKA,* Sakie MORITA,* Atsunobu IZAWA,* Keisuke AOYAMA,* Ki-Cheol SHIN,** and Takanori NAKANO**
*Food and Agricultural Materials Inspection Center Kobe Regional Center, 1-3-7 Minatojima-minami-machi, Chuo, Kobe, Hyogo 650-0047, Japan
**Research Institute for Humanity and Nature, 457-4 Motoyama, Kamigamo, Kita, Kyoto, Kyoto 603-8047, Japan
The strontium (Sr) isotope ratio (87Sr/86Sr) and Sr content were used to trace the geographical origin of onions from Japan and other countries, including China, the United States of America, New Zealand, Australia, and Thailand. The mean 87Sr/86Sr ratio and Sr content (dry weight basis) for onions from Japan were 0.70751 and 4.6 mg kg−1, respectively, and the values for onions from the other countries were 0.71199 and 12.4 mg kg−1, respectively. Linear discriminant analysis was performed to classify onions produced in Japan from those produced in the other countries based on the Sr data. The discriminant equation derived from linear discriminant analysis was evaluated by 10-fold cross validation. As a result, the origins of 92% of onions were correctly classified between Japan and the other countries.