Phase change or not: oil in the refrigerator

[Spinnor]

Cooked some french fries last night using oil saved in the refrigerator. The oil appears to have undergone a phase change, after some time in the refrigerator instead of being a yellowish transparent liquid it was a semi-solid soft whitish non-transparent stuff when I took it out of the refrigerator to use it to cook. This morning it was still a yellowish transparent liquid. When the oil changes from a transparent liquid to a semi-solid soft whitish non-transparent stuff that technically a phase change? Over time honey also seems to undergo a similar "phase change".

Thanks.

 

[DrClaude]

Yes, oil will become solid as it goes below a certain temperature. It is the usual phase transition from liquid to solid.

What happens with honey is quite different. It is much more a mixture, and what is observed is the crystallisation of the sugar separating out of the mixture.

 

[JT Smith]

Most cooking oils are mixtures of lipids so often there isn't a sharp transition from liquid to solid. As the temperature is lowered parts of the mixture will freeze first, producing a cloudy, viscous liquid/solid mixture. Below a certain temperature it will be completely frozen.