Analysis of the mineral composition of taro for determination of geographic origin

The mineral composition of taro ( Colocasia esculenta (L.) Schott) was analyzed to develop a method to distinguish taro produced in Japan and China. The concentrations of 15 elements (Al, Ca, Cl, Mg, Mn, Br, Co, Cr, Cs, Fe, K, Na, Rb, Sc, Zn) were assayed using instrumental neutron activation analysis. The concentrations of NO(3)(-), SO(4)(2-), H(2)PO(4)(-), Cl(-), malate, and oxalate were measured by ion chromatography. The mean concentrations of H(2)PO(4)(-), Co, Cr, and Na significantly differed (P < 0.01) between taro grown in Japan and that grown in China. Discriminant analysis was performed to identify the most efficient combination of elements and compounds to discriminate the taro geographic origin. The highest percentage of correct classification was achieved with a two-variable model including H(2)PO(4)(-) and Co (100% for Japanese, 93.75% for Chinese). Principal component analysis and cluster analysis using all of the assayed elements and compounds were also conducted to determine which elements significantly accounted for the variation of the taro mineral composition. We report on the potential of H(2)PO(4)(-) and Co concentrations to differentiate taro grown in China and Japan and discuss the sources of variability in the taro mineral composition of our samples.