Abstract
We determined stable carbon, nitrogen, and oxygen isotopic compositions (δ13C, δ15N and δ18O) of blanched and salted wakame (Undaria pinnatifida) from major cultivation areas in Japan (Naruto and Sanriku), China and South Korea to evaluate whether the isotopic compositions could be used to identify the geographical origin of blanched and salted wakame. A total of 209 samples from three different plant parts (top, middle, and bottom) were analyzed for carbon and nitrogen isotopic compositions. In addition, 77 samples (top, middle, and bottom) were analyzed for oxygen isotopic composition. The variations in the isotopic compositions ranging from 0.2 to 2.0‰ for carbon and 0.1 to 1.4 ‰ for nitrogen are found between different parts of a single wakame plant, which is small enough to discriminate Naruto wakame (−16.6±0.9‰, mean±1σ for carbon and 10.7±1.1‰ for nitrogen) from the wakame of other regions (−17.1±1.9 ‰ for carbon and 1.7±2.8‰ for nitrogen). Indeed, linear discriminant analysis revealed that 98.4 % of Naruko wakame can be distinguished from the other regions. However, no marked differences in the oxygen isotopic composition was observed between wakame from Naruto (19.3±0.8‰, mean±1σ), Sanriku (18.3±0.6‰), China (19.1±0.9‰), and South Korea (20.4±0.5‰). We conclude that the carbon and nitrogen isotopic compositions are potentially useful for discriminating between wakame from Naruko and wakame from other areas.
