Waxy fraction containing long-chain aliphatic aldehydes in virgin olive oils

► Aldehydes with even carbon-atom from C22 to C30 are present in olive oils. ► Concentrations of total long-chain aliphatic aldehydes in olive oils are below 116 mg kg−1. ► Hexacosanal (C26-al) is the most abundant aldehyde in olive oils. ► Long-chain aliphatic aldehydes is a good traceability markers for olive oils.