Electronic nose: a tool to verify the PDO declaration of Portuguese olive oils

The volatile and olfactory profiles of three Portuguese olive oils with protected designations of origin (PDO) were studied: “Azeite do Alentejo Interior”, “Azeites da Beira Interior”, and “Azeite de Trás-os-Montes”. Seven classes of volatiles were identified, with aldehydes, followed by hydrocarbons and alcohols, the most prevalent (5.63, 2.92, and 2.79 mg/kg olive oil, respectively). The “Azeites da Beira Interior” oils exhibited the highest amount of volatiles (18.2 ± 4.6 mg/kg olive oil) compared to the oils from the other two PDOs. Ten positive olfactory sensations were detected, and a significant effect of the PDO on the intensities of fruity, apple, cabbage, tomato, dry and fresh herbs was observed. Specifically, “Azeite do Alentejo Interior” PDO oils were characterized as fruity-ripe, while “Azeite de Trás-os-Montes” PDO oils were labelled as fruity-green. Conversely, “Azeites da Beira Interior” PDO oils encompassed both fruity-ripe and fruity-green oils. Unique volatile and olfactory fingerprints were established for each PDO, allowing the linear discrimination of the oils according to the PDO, with a predictive sensitivity of 98.0 ± 4.2