Elemental and isotopic profiling of Thai jasmine rice (Khao Dawk Mali 105) for discrimination of geographical origins in Thung Kula Rong Hai area, Thailand

Discrimination of Thai jasmine rice (Khao Dawk Mali 105) according to their geographical origins was studied to prevent mislabeling and adulteration problems of rice. Thai jasmine rice was collected in paddy fields in Thung Kula Rong Hai area, in the northeast of Thailand. The studied elements were determined by comparative method with the certified reference materials (NIST 1568a). Elemental compositions (As, Mg, Cl, Al, Br, Mn, K, Rb and Zn) in Thai jasmine rice were analyzed by instrumental neutron activation analysis (INAA) whereas stable isotopes (δ13C, δ15N, and δ18O) were analyzed by elemental analyzer isotope ratio mass spectrometry (EA-IRMS). The twelve key variables were used as chemical indicators to discriminate the geographical origins of Thai jasmine rice in Thung Kula Rong Hai area. Radar plot and multivariate statistical analysis were performed. Classification of rice origins (5 provinces) was achieved with 100% correct classification of their original groups and 75.5% cross-validation.