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Original Articles

Targeted and non-targeted detection of lemon juice adulteration by LC-MS and chemometrics

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Pages 560-573 | Received 23 Oct 2015, Accepted 30 Dec 2015, Published online: 17 Feb 2016
 

ABSTRACT

Economically motivated adulteration (EMA) of lemon juice was detected by LC-MS and principal component analysis (PCA). Twenty-two batches of freshly squeezed lemon juice were adulterated by adding an aqueous solution containing 5% citric acid and 6% sucrose to pure lemon juice to obtain 30%, 60% and 100% lemon juice samples. Their total titratable acidities, °Brix and pH values were measured, and then all the lemon juice samples were subject to LC-MS analysis. Concentrations of hesperidin and eriocitrin, major phenolic components of lemon juice, were quantified. The PCA score plots for LC-MS datasets were used to preview the classification of pure and adulterated lemon juice samples. Results showed a large inherent variability in the chemical properties among 22 batches of 100% lemon juice samples. Measurement or quantitation of one or several chemical properties (targeted detection) was not effective in detecting lemon juice adulteration. However, by using the LC-MS datasets, including both chromatographic and mass spectrometric information, 100% lemon juice samples were successfully differentiated from adulterated samples containing 30% lemon juice in the PCA score plot. LC-MS coupled with chemometric analysis can be a complement to existing methods for detecting juice adulteration.

Acknowledgements

The authors would like to thank Dr Artemio Z. Tulio, Jr and Zhaobin Wang for performing the total titratable acidity, °Brix and pH measurements; Jing Bai and Xuelin Zhang from the Illinois Institute of Technology for preparing lemon juice samples; Dr Kevin Kubachka from the USFDA Forensic Chemistry Center for providing IRMS knowledge; and Dr Ralf Tautenhahn from Thermo Fisher Scientific, Inc. for technical support.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data for this article can be accessed here.

Additional information

Funding

This project was supported in part by an appointment to the Research Participation Program at the Center for Food Safety & Applied Nutrition administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the US DOE and the USFDA.

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