Hass avocado (Persea americana Mill.) oil enriched in phenolic compounds and tocopherols by expeller-pressing the unpeeled microwave dried fruit.

This study investigated how the quality of avocado oil is affected by the fruit ripening stage and peeling, and the drying process used. Expeller pressed avocado oils were obtained from unripe or ripe pitted avocados after drying peeled or unpeeled pulps by convection oven, microwave or freeze-drying. Oils from the unpeeled microwave dried pulp (from unripe or ripe avocados) showed the highest induction period (54.2-83.6 h) and antioxidant capacity (4.07-5.26 mmol TE/kg), and high amounts (mg/100 g) of α-tocopherol (11.6-21.0), ß-carotene (0.49-0.65) and chlorophyll (44.3-54.0), and unsaponifiable matter (2.48-2.99 g/100 g). Pulp drying process and avocado (un)peeling were the major contributors to the induction period (R2 = 0.61; p = 0.0139) and antioxidant capacity (R2 = 0.62; p = 0.011), and the oils from microwave dried unpeeled pulp were those that presented the best performance. The phenolic composition of these oils improved with ripening and keeping the peel during the pressing process.