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Q & A: oil in pasta water

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Most recent answer: 01/30/2020
Q:
How does cooking oil disperse in boiling water? I ask because recipes for pasta sometimes say that adding a few drops of oil to the water will keep the pasta from sticking together. I haven't noticed much difference and it looks like the oil stays in blobs near the surface.
- Jack Pommer (age 59)
Boulder, CO, US
A:

I have the same impression as you. Sometimes if you scoop the pasta up or pour it through a colander, though, the oil gets on the pasta. I don't think that enough dissolves in the water to make much difference. The enthalpy of solution of oleic acid in water is about 122kJ/mol, which means that even at 100°C very little will dissolve. (That enthalpy is approximately the amount of energy required to take an oil molecule out of the oil and put it in the water. Thermal energy even at 373K=100°C is far less than that.)

Mike W.


(published on 01/30/2020)

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