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UEMcGill t1_j7foa0e wrote

"Boiling" for water is when the vapor pressure of the liquid, equals the ambient air pressure. Water at any pressure has a vapor component, it just happens to be a lower pressure typically than ambient pressure. That's why you can leave a glass of water out, and eventually it will evaporate.

Oil's have a vapor pressure also, it just happens to be much higher than water. We boil oil all the time, as this is typically how it is refined and processed, even vegetable oils. However some oils decompose, before they get to their boiling point.

Frying as others have said is when you boil water out of food, using hot oil.

If you put water under a high enough vacuum, even at room temperature the vapor pressure will equal the ambient temperature and it will boil. In cities like Denver you have to adjust baking and cooking because water actually boils lower than the typical 212F/100C

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TheLostHippos t1_j7fqkig wrote

They definitely do not boil the oil to refine it as the smoke point is so much lower it wouldn't make any sense. They heat the oil to like 180f and add an alkaline substance. There are some steaming processes later on but they stay about 100f (400-450f steam temp) below the actual boiling point of the oil and this process deodorizes the oil.

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UEMcGill t1_j7g56yu wrote

Hexane extraction using fractjonal distillation was a common method for vegetable oil production. So yes in part the oil will be boiled. It's not what a pot on your stove would look like, and takes into account vapor pressures differences, but it boiled would be an accurate description.

Signed, a Chemical Engineer.

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