Detection of Falsely Labeled Taro in Japan by Elemental Analysis: Improvement of Discrimination Ability Using a Sampling Plan

Abstract

Thirteen elements (Na, Mg, P, Ca, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Cd and Ba) in the compositions of 230 taro samples (118 Japanese fresh, 35 Japanese frozen, 36 Chinese fresh and 41 Chinese frozen) were determined by ICP-AES and ICP-MS. Linear discriminant analysis and a support vector machine were used on the compositions. A discriminant model to detect Chinese taro from those of Japan was constructed with Mg, Ni, Zn, Rb and Cd. Receiver operating characteristics and sampling plans were examined to improve discrimination ability. The sensitivity for Chinese fresh and frozen taro was estimated to be 79.4% and 73.2%, with false positive rates of 1.7% and 2.5% for Japanese fresh and frozen taro, respectively.