To be precise, extra virgin olive oils are processed in 4 main, different ways.
Traditional milling (millstones, press, and jute mats), 3-phase continuous cycle, 2-phase continuous cycle, and Sinolea: when applied to the same batch of olives, these methods yield oils with vastly different sensory profiles and properties (both positive and negative). Hardly any consumers ask about this, and very few back labels highlight it, but the 2-phase continuous cycle and Sinolea are the two best technologies. Expect a higher price for oil produced using the Sinolea method, as the yield is lower.
To sum up, try and look for your preferred Extra Virgin Olive Oil with a high polyphenol content, low peroxide levels, a free acidity index not exceeding 0.5, and one that was processed within 24 hours of harvesting.
Last but not least, should you cook warming up Extra Virgin Olive Oil (fried vegetables, sauces etc) do not hesitate and go for a 2-phase continuous cycle milling. Polyphenol level -the highest possible' will act as a buffer to protect the Oil against oxidation.
On the other hand, should you dress your food with room temperature Extra Virgin Olive Oil, take into consideration that the cultivar and the Polyphenol level will reflect into a higher evidence of both bitterness and pungentness! But this is only a matter of pairing the food with its matching oil and ...not to forget, your personal taste! In this case, the 3-phase continuous cycle method is absolutely fine.
— Ettore Bellucci