Some facts about your question:
- Polyphenol presence in olive oil is due mostly to the high presence of hydroxytyrosol and oleuropein. These compounds are also the ones that give the Early Harvested Oils (Harvested mid-October to end-January) their bitter pungent taste. Their higher concentrations in the beginning of fruit maturation (while olives are still green) is the reason for such an oil's bitter taste when compared to one produced with more mature olives (olives having turned dark eggplant purple). The most bitter ones are the oils of the year in hand, since with time that same oil will sweeten and change coloration to a green-yellow shade.
- Oils which have not been filtered but decanted will have a higher content of polyphenols as well. Filtering diminishes qualitative attributes of the oil.
- Controlled temperature during the olive pressing process is a factor as well being that high temperatures diminish its qualitative attributes as well
- And finally, the type of olive cultivated plays a major role. I will only inform you on the Greek varieties which I know best, and the highest polyphenol content is found in the Koron?iki, Mastoid?s (Athinoli?-Tsoun?ti), Mirtoli?, Agouromanakoli?, and Dafneli?.
These are the main factors you should be looking for when searching for such types of oil. The freshest harvests are usually not taken out in the market yet because the oil's taste is so strong that consumers assume that the oil has gone bad. Here in Greece, such traditional oils (Not Commercial Blends) are kept in storage for one whole year to decant and sweeten, and only consumed as of the following harvest (the smaller harvest).
I hope this was helpful,
Ioannis Grimpilas - Production and Sales Team Coordinator
Georgiou Androutsou 16, Athens - 11741, Greecegourmet@pertorqueo.com http://www.pertorqueo.com