I've read Gut by Guilia Enders. It says that extra virgin olive oil cleans your heart vessels and has other beneficial effects. The oil binds free radicals in your body. But the oil doesn't wait to bind radicals, so if it's exposed to air it will bind the free radicals in the air, making the oil less effective.
Her advice is to close the bottle, and to keep the oil cool, in the fridge. When I do this, the oil solidifies, making it unusable. Waiting until it warms up takes too long. My kitchen is not cool in the summer. Temperatures can go up to 25ºC and higher.
So how can I keep oil cool in a warm kitchen or not too cold in a fridge?
Best Answer
As @GdD said in his comment - you can't, unless you have a way to cool it to a defined temperature such as a cooling water-bath. Olive oil is perfectly fine at higher temperatures than 25 - this would be on the cool side for a Greek (as big users and preparers of olive oil) summer, especially before the presence of air-conditioning:
From here.
As to slowing down oxidation from the free-radicals, yes, keeping it in the fridge will work to some extent as in the crystalline phase the oils will be less susceptible to oxidation. Indeed I found one study that looked at oxidation and storage of olive oils at different temperatures and with different packaging types, who found that the shelf-life of the oils was best in green glass (GG) and at 6 Celsius - see quote below (EVOO is Extra virgin olive oil, TT is tinplate tin).
Incidentally they found that storage under any conditions for more than a month meant that the oils no longer met the legal requirements for extra virgin oil. This would imply that your best bet for keeping oil is indeed to store it in the fridge and in a green glass bottle, and use it rapidly.
However, as you noted, storage in the fridge results in the oil becoming solid, so you either have to live with some solid oil and re-warm it each time you want to use it, or come to some compromise such as just storing it in the dark but not cold.