The ideal temperature for storing extra virgin olive oil is between 14 and 18 degrees, but when winter comes the oil may well be exposed to colder conditions. It is even possible that the oil will freeze and solidify. This is a completely natural process.
As the oil freezes, a growing number of small white spheres will start to appear in it. If the bottle continues to be kept at very low temperatures, the oil will solidify completely.
You may well think that olive oil cannot freeze. However, like all other lipids, extra virgin olive oil is made up of fatty acids, and with a fall in temperature, these will freeze and make it go solid.
As the temperature drops, the fats in the olive oil go through two stages. Between 8 and 10 degree, crystallisation occurs, and small white spheres begin to form on the surface. Between 4 and 5 degrees, the oil solidifies.
This process may occur in winter if the weather changes during transport, or if the oil is stored in an unheated warehouse. But the solidification process is completely reversible. When the bottle is kept at room temperature, the oil will resume its normal consistency and will be ready for use in the kitchen.
After it has thawed out, you may notice a deposit in the bottom of the bottle. In this event, it is good idea to filter or decant the oil to avoid an acceleration of the ageing process.