Rapid Test for Traceability Assessment in Lemon Juice by High‑Performance Liquid Chromatography Fluorescence

Fruit juices, especially lemon juice, are the most targeted food goods for adulteration and fraud in Iran. The aim of this study was to investigate the profile and concentration of free primary amino acids as a marker for adulteration in lemon juice.

Amino acids were determined with high‑performance liquid chromatography fluorescence. The limit of detection and limit of quantification were in the range of 0.008–0.01 ng/ml and 0.03 ng/ml, respectively.

The method is suitable for distinguishing authentic juices from drinking products that may contain little or no fruit juice. In our study, total amino acid concentration in natural lemon was 13.15 mmol/l and in other brands was in the range of 1.81–14.84 mmol/l. Further, the concentration of aspartic acid, glutamic acid, asparagine, and serine was more than other amino acids. The findings showed that only brands 1 and 2 were considered similar to natural lemon juice.

The present study demonstrated that the concentration of the first four amino acids can use as a marker to determine lemon juice adulteration.