Application of carbon and hydrogen stable isotope analyses to detect exogenous citric acid in Japanese apricot liqueur

Japanese apricot liqueur manufacturers are required to control the quality and authenticity of their liqueur products. Citric acid made from corn is the main acidulant used in commercial liqueurs. In this study, we conducted spiking experiments and carbon and hydrogen stable isotope analyses to detect exogenous citric acid used as an acidulant in Japanese apricot liqueurs. Our results showed that the delta C-13 values detected exogenous citric acid originating from C-4 plants but not from C-3 plants. The delta H-2 values of citric acid decreased as the amount of citric acid added increased, whether the citric acid originated from C-3 or C-4 plants. Commercial liqueurs with declared added acidulant provided higher delta C-13 values and lower delta H-2 values than did authentic liqueurs and commercial liqueurs with no declared added acidulant. Carbon and hydrogen stable isotope analyses are suitable as routine methods for detecting exogenous citric acid in Japanese apricot liqueur. (C) 2017 Elsevier Ltd. All rights reserved.