Ripening, Oleuropein, and Curing

Olives turn from green to black as they ripen. Depending on when they are harvested, the oleuropein content in them will differ. Green olives tend to have more polyphenols than black olives, which are allowed to ripen for a longer period of time. Because of this green olives have a higher concentration of oleuropein than black olives. According to The Olive Source "The polyphenol concentration increases with fruit growth until the olives begin to turn purple and then begins to decrease." Therefore it is logical to conclude that it would take a longer time to cure olives with a higher concentration of oleuropein (green), than those with a lower one (black). This may of course change according to the varietal of the olive as well.

Sources: http://www.oliveoilsource.com/page/chemical-characteristics