So, I am kind of physics dumb. I have found the equation for water evaporation from a pool and I have been attempting to make work and make sense for creating a spreadsheet that will help me predict the amount of water evaporation from milk while cooking it in order to create a reduction.

My question has 2 parts in that sense: How do i figure out the rate of evaporation of water for milk (I really need help breaking this down)?


How can I put it into a spread sheet where I can easily edit it as the variables change?

Right now, my variables are as follows: constant temperature for milk of 71°C, controlled room temperature of 70°F, and a pot of 30cm diameter.

As of right now, the humidity is very different from day to day (does higher humidity mean less evaporation?) and I have no way of calculating velocity of my kitchen air, however I am thinking of adding a fan in order to increase evaporation rate.

Is that enough information to have someone help me answer my question? I would really appreciate a break down of the math so that I can put it into a spread sheet for future use.

Thanks, Aric

  • $\begingroup$ really, it's quite impossible to compute this evaporation from scratch. But you can measure the weight of the pot and deduce a solution for you exact experimental / production context. $\endgroup$ – user46925 Aug 23 '15 at 10:31

The problem you face is this: water is a homogeneous collection of one type of molecule. Milk is a heterogeneous collection of hundreds of different molecules, some of them quite large. Now, any given molecule, if in a homogeneous assembly, has a measurable partial pressure, which defines (roughly) the evaporation rate. However, once you mix molecules, even as simply as, say water and $NaCl$ , there are interaction effects which change the evaporation rate for each specie.

Milk itself varies in composition from cow to cow (not much, but it will vary), not to mention depending on the processing applied before it reaches a store. This means that you can, via experiment as igael suggested, get a rough measure of the evaporation rate, but you will also discover that the water evaporates faster than fat globules, so you'll be left with a residue. So, how do you define "milk evaporating" ?

  • $\begingroup$ In that sense, I am simply trying to evaporate the water from the milk. So, could I not just use the formula for water evaporation as a rough guideline? Milk is approximately 89% water... Yes I can do a rough estimate, which I do each time I cook it, but I would like to have a formula where I can plug in different temperatures and other variables to see how they affect the outcome. $\endgroup$ – Aric Aug 25 '15 at 2:13

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