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Oils that remain a clear color in the refrigerator are unsaturated.
Unsaturated fats are those with double bonds in their fatty acid chain. These are known as being "healthier" than the saturated fats, which don't have any double bonds. Unsaturated fats, when put into the refrigerator are harder to become solid and change color than saturated fats because the double bonds make the structure to have less intermolecular interactions by steric hindrance and thus a lower melting point.
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