As the question states, when boiling/steaming kale, do the omega 3 oils get boiled out? I imagine the answer is yes similar to how oil gets boiled out from chicken or meat in a soup.
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2 Answers
The omega-3 fatty acids will not be boiled out.
The omega-3 fatty acid content of kale and spinach is mainly made up of ALA (alpha-linolenic acid). This can be seen on nutritional profiles for these vegetable, e.g. on http://nutritiondata.self.com/. It is the case for most popular plant food that the omega-3 content is mostly made up of ALA.
The temperature when steaming or boiling will be around 100 degrees Celsius, which is the boiling temperature of water. The boiling point of ALA is around 230 degrees Celsius [1] , and so the ALA will not boil out if you steam or boil vegetables in water.
You might, however, be more interested in whether to fatty acids change in some other way due to the temperature. The primary concern would be the oxidation of the fatty acids. I did found one study [2], referenced from the Wikipedia page about ALA, which states that ALA remains stable during cooking.
Note that if you are using a pressure cooker, the temperature may get higher; up to ~120 degrees Celsius. The ALA will still not boil out, but I am not sure how this will affect oxidation.
To summarize, if you are boiling or steaming kale/spinach, you can be quite confident that the omega-3 fatty acids will still be there after you finish cooking.
References:
[1] Pubchem. 2017. linolenic acid | C18H30O2 - PubChem. [ONLINE] Available at: https://pubchem.ncbi.nlm.nih.gov/compound/linolenic_acid#section=Physical-Description. [Accessed 28 January 2017].
[2] Manthey, F.A., Lee, R.E. and Hall, C.A., 2002. Processing and cooking effects on lipid content and stability of α-linolenic acid in spaghetti containing ground flaxseed. Journal of agricultural and food chemistry, 50(6), pp.1668-1671.
Let's use the term evaporate rather than boil.
Clothes dry on the line at less than the boiling point of water.
The mix of the vapor will depend on the vapor pressure at 100 °C (212 °F).
I cannot find a vapor pressure chart for omega 3. Given the boiling temperature is 231 °C it is clearly less volatile than water. The vapor will be primarily water but the omega 3 content will not be zero.
Table salt with a boiling point of 1465 °C - that would be virtually zero at 100 °C.
