Geographical origin of polished rice based on multiple element and stable isotope analyses

We determined carbon and nitrogen contents (C and N contents) and stable carbon, nitrogen, and oxygen isotopic compositions (delta C-13, delta N-15, and delta O-18) of polished rice in order to develop a simple method to discriminate its geographical origin. As a first attempt, we examined a single cultivar, Koshihikari rice, from 14 different cultivation areas including Australia (n = 1), Japan (n = 12), and USA (n = 1). For all rice samples, C and N contents and the isotopic compositions are consistent with those of general plant materials, being 37.2-40.0% (C content), 0.8-1.4% (N content), -27.1 to -25.4% (delta C-13), +0.4 to +9.0% (delta N-15), and +18.8 to +22.9% (delta O-18). However, its cultivated area is clearly distinguished by a pentagonal radar plot based on the elemental and isotopic compositions. Thus, the comparison of C and N contents and delta C-13, delta N-15, and delta O-18 values would potentially be useful for rapid and routine discrimination of geographical origin of the polished rice. (C) 2008 Elsevier Ltd. All rights reserved.