Olives are high in polyphenols. These substances are water soluble so are mostly found in the waste water after olive processing. The levels are so high that they represent one of the biggest problems in disposing of olive waste.
The phenols have anti-fungal and anti-bacterial activities so can disturb normal wetland or treatment pond ecology. The oil retains a small amount of the polyphenols. The altitude of the olive grove and the ripeness of the fruit help determine the exact type of polyphenols. Some of these acids are destroyed during olive ripening while other ones increase. Overall there is no difference in the quantity of phenols between green semi-black and ripe olives.
Oil made from green olives will give a lower yield but seems to have the most favorable type of polyphenols as the shelf life is considerably longer. Oil from green olives is frequently mixed with oil from mature olives to extend its shelf life. Some of the polyphenols such as hydroxytyrosol have been found in higher concentrations in good quality oils while tyrosol and some other phenolic acids are found in poor quality oils. The difference between virgin and extra virgin is the acid content and organoleptic properties such as taste, so undoubtedly extra virgin has different polyphenols than virgin but as before the total amount of polyphenols are probably the same. Producers are just now looking into creating health products based on the olive water.