Development of a SCAR marker for the identification of Olea europaea L.: A newly detected adulterant in commercial Mediterranean oregano

► A new contaminant of commercial oregano has been detected by means of pharmacognostic analysis. ► The contaminant has been identified as crushed leaves of Olea europaea L. ► A new method based on SCAR-PCR molecular markers has been developed. ► The new contaminant can be detected in amounts as low as 1% in multiple commercial batches.