Bilberry adulteration: identification and chemical profiling of anthocyanins by different analytical methods

Extracts of the bilberry fruit have protective effects against retinopathy and vascular complications; therefore, they are important ingredients in food supplements. Recently, there have been several reported cases of adulteration. Thus, to characterize the anthocyanin profile, and the relative percentages of these pigments, this study analyzed bilberry fruits from different countries by liquid chromatography coupled to a diode array detector and a mass spectrometer detector. A total of 15 anthocyanins were identified, and a fingerprint profile was used for the quality control of the target material. Fourteen bilberry extracts and 12 finished products labeled as bilberry from different marketing manufacturers were analyzed. Approximately 50% of these extracts differed significantly from the reference bilberry, suggesting possible adulteration. Approximately 60% of the extracts and 33% of the food supplements presented a lower anthocyanin content than declared. The adulterations were observed mainly with extracts of mulberry and chokeberry.