Melted butter

[majormark]

I noticed that if I leave butter in a room where the temperature exceeds 30°C, it melts partially.

I haven't noticed any problems after eating it like that a few times, but it has a different taste. I almost feel like I'm eating oil.

Anyone have more experience with this?

[alphagruis]

Butter is roughly an emulsion of water in fat. Milk is the reverse.

http://www.foodsci.uoguelph.ca/dairyedu/butter.html

This means butter is made of fat with a small amount about 15% of a water based liquid dispersed in it in the form of tiny globules. (For fundamental reasons of physics fat and water cannot mix more intimately at molecular level in metastable form.)

Upon heating it at temperature about 30°C or so the fatty acids with lowest melting point begin to melt and phase separation takes place with fatty acids with higher melting points still in solid form.

The fatty acids triglycerides melting first upon heating are precisely those with polyunsaturated and monounsaturated chains such as oleic acid. This gives the liquid part an oily taste similar to some plant seed oils.

In terms of flavor of liquid part you loose much of the tiny amount of protein, salt, sugar etc of the original emulsion that gives unmelted butter its taste.