Two tons of olives Cv Carboncella were harvested and processed within 24 h in two industrial scale olive mills (Pieralisi, Italy), equipped with “two-phases” (P2) and “three-phases” (P3) centrifugation systems. The malaxing chambers of both olive mills were sealed, connected with a nitrogen tank and equipped with a sensor for the O2 level monitoring. In each olive mill, olives were malaxed (35 min at 27 °C) in four rounds (200 kg of olives each). In each olive mill, the first round of malaxation (R1) was performed without modifying the atmosphere, whereas for the remaining rounds nitrogen was flushed in the chamber, modulating the amount of O2 as follows: R2: Oxygen 12.73 to 4.64 kPa from the beginning to the end of malaxation; R3: from 10.46 to 2.27 kPa; R4: from 9.87 to 0.69 kPa. In P2 neither water nor any technological co-adjuvants were added to the olive paste during the malaxation, whereas in P3 75 L water/100 kg olive paste were added into the malaxing chamber.
Samples of the obtained oils were stored in dark glass bottles and placed in a closet in a cool room at constant temperature of 17 ± 3 °C. The first round of chemical and sensory analyses was performed one month later (t0), and then repeated at four (t1), seven (t2), ten (t3), and thirteen (t4) months of storage.