Before writing this article I wasn’t too worried about storing olive oil at my house because it simply doesn’t last very long. I knock back about 1 bottle a month as I use it in pretty much everything I prepare.

I don’t skimp when it comes to purchasing olive oil either. As a general rule I buy extra virgin for preparing dressings or any time I finish a dish with oil. For high-heat cooking I use the milder “extra light” oils. Olive oil can be very expensive so it is good information to know how to properly store it.

Oxidation
The biggest thing you have to worry about with oils is oxidation. Oxidation refers to the decomposition of fats, oils and other lipids due to the formation of free radicals. This process is responsible for producing unpleasant odors and flavors. Oxidation may also destroy any nutrients found in the oil and in the right conditions the destruction of vitamins can occur very quickly. [1]

Heat, oxygen, and light are the primary enemies of cooking oils because they stimulate the development of free radicals that lead to oxidation. Oxidation is going to happen either way, but you can greatly decrease the process by storing your fats and oils in a cool, dark place.

Storage
Since heat and light accelerate the rate of reaction of fats with oxygen here are a couple of pointers for storing your oil.

1. If possible, store oils at 57 degrees Fahrenheit. Since, like most people, I don’t have a wine cellar this can be a tall order. As a general rule, if you have a steady room temperature of about 70 degrees Fahrenheit you should be fine, but anything regularly warmer than that should be refrigerated. Remember, refrigerated oil will solidify and turn cloudy. Just set the oil out prior to using it so that it returns to its normal form. [2]
2. To prevent light from activating free radicals, store your olive oil in opaque bottles. Or keep it stored out of direct sunlight. I make a point of buying oils that come packaged in opaque bottles just in case it sat in the sun during the shipping process.

After researching this article I need to think twice about how I’m storing my own olive oil. If you don’t go through your oils quickly it is probably best to keep it stored in the refrigerator and discard it if it is old. Olive oil can make or break the dish so make sure you have the best you can buy and store it accordingly.

Reference:

1. http://en.wikipedia.org/wiki/Rancidification
2. http://recipes.howstuffworks.com/how-olive-oil-works3.htm