If you like to keep a bottle of olive oil on your kitchen countertop, there is an easy step you can take to avoid having it go bad. When it comes to preserving olive oil, there is one major enemy: light. The more light the olive oil faces, the more free radicals are generated, which leads to oxidation and rancidity of the oil. To avoid this, choose a glass bottle that has a blue or green tint to it, which will act as a natural UV light barrier. You can also use a metal container, but choose a non-reactive metal like stainless steel, not iron or copper, which will react poorly with the oil.