The effect of processing on the trace element composition of wakame (Undaria pinnatifida): Implications for geographical origin analysis

Abstract

We evaluatedthe effect of processing (i.e., boiling, salting, and washing) on the trace element composition of wakame (Undaria pinnatifida), to accurately assess the geographical origin of wakame products on the market. The trace element composition (Mg, P, Ca, V, Mn, Fe, Zn, As, Rb, Se, Cd, and Ba) was significantly alteredby processing, likely due to (1) elimination and/or dilution of the elements during processing, (2) contamination from salts, and (3) decrease of wakame content per unit weight by salting. However, the Ba content of wakame was relatively resistant to the elimination and contamination effects during processing, and the effect of dissolution couldbe correctedby a simple calibration. These results suggest that Ba content can be employedas a reliable factor to distinguish the geographical origin of wakame, even after processing. Indeed, the Ba content in wakame and wakame products from China (25.6±5.7ppm) is much greater than that from other sources (i.e., Sanriku: 8.6±1.9 ppm, Naruto: 10.9±2.3 ppm, and South Korea: 14.2±4.6ppm), allowing for the discrimination of sources (i.e., China and others) of wakame and wakame products by 90.0% and95.9%, respectively.