Characterization of volatile compounds and biological activities of olive and oleaster oils from different Algerian altitudinal localities

This study investigates the chemical composition and bioactivities of olive oils obtained from three cultivars: Chemlal (CH), Azeradj (AZ), and Aberkane (BK), as well as oleaster oil (Azebouj (ZB)), originating from two altitudinal locations: high (1) and low (2). Bitterness index, chlorophyll content, total phenolic content (TPC), ortho-diphenols, antioxidant activity, antimicrobial activity, and volatile organic compounds were determined. The results revealed that regardless of altitude, the oleaster oils (ZB1 and ZB2) showed the highest bitterness index and TPC (593.36 and 492.58 mg GAE/kg, respectively), compared to the cultivated olive oils. The chlorophyll concentration varied significantly, with BK1 having the highest concentration (12.82 ppm), contrary to that of AZ2 (2.53 ppm). Antioxidant activity indicated that CH2 oil exhibited the highest reducing power (597.27 mg AAE/kg) and hydrogen peroxide scavenging activity (94.29%), while ZB1 showed the highest DPPH radical scavenging (51.72%). BK1 oil was most effective in the β-carotene bleaching assay (60.07%). Antimicrobial tests showed that CH2 and BK1 oils were effective against Candida albicans and Staphylococcus aureus, respectively. SPME–GC/MS analysis revealed significant variations in the volatile profile of the studied oils. Except for BK2 oil, which showed the highest aldehyde content (1300.8 μg/kg), CH1 oil exhibited the most distinct volatile profile and had the greatest amount of major classes: total alcohols (7570.6 μg/kg), esters (2294.1 μg/kg) and terpenes (734.3 μg/kg). These findings indicate that both cultivar and altitude significantly impact the oil's phenolics and volatile compounds, providing valuable insights for the olive oil industry as a food ingredient and potential health applications regarding their antifungal and antibacterial activities.