Determination of Adulteration of Lime Juices in Tabriz Based on Measurement of Phenolic Compounds by Spectrometry and Chromatography

Background & objectives: Citrus lemon and lime juice, which contain high levels of vitamin C and natural antioxidant in the form of polyphenols, have a special place in the food basket of Iranian households. Flavonoids are among the polyphenolic compounds and Eriocitrin, Naringin and Hesperidin are among the most important flavonoids. Investigating the amount and type of polyphenols and flavonoids in this food is one of the tools to discover the authenticity of this juice. Methods: In this research, 65 samples of lime juice (42 samples of packed lime juice and 23 samples of bulk lime juice) were purchased from Tabriz and total amount of phenolic compounds were determined using spectrophotometry. Also, the quantities of Eriocitrin, Naringin and Hesperidin were analyzed using liquid chromatography method in order to investigate possible counterfeiting. Results: The average amount of total polyphenolic compounds of packed and bulk juices were 275 and 303 mg/l, respectively and totally, 9 samples (13.8%) did not conform to the Institute of Standards of Iran rules and were considered as not consumable. Regarding flavonoids, the results showed that the average amount ​​of Eriocitrin, Naringin and Hesperidin were 17.32, 28.31 and 80.44, respectively. Accordingly, 33 samples (50.78%) were not consistent with the Institute of Standards of Iran rules. In the present study, the reason for the non-standardization of most lemon juice samples (78.8%) was presence of the Naringin flavonoids. Conclusion: In determining flavonoid compounds in comparison with the method of measuring total phenolic compounds, 24 more samples of lime juice (36% of samples) were found not to be standard, so due to the increasing adulteration that occurs in the various food industries, it is imperative that food health monitoring institutions use new and effective methods for food authentication to ensure community health.