Another reason for the instability of an oil made from unripe olives could
be the presence of degradative enzymes such as lipoxygenases and polyphenol
oxidases. We know that some of these enzymes are present in olives - they
have been detected even in olive oil. I don't know how active they are in
unripe olives.
We also cannot rule out bacterial activity, particularly if the water
content of an oil is fairly high. Incidentally, what is the water content
of extra virgin olive oil? Is it a problem?

Alfred Poulos
Megisti Oils
www.megistioils.com