Sunday, July 18, 2010
Question: Melting points of butters?
What a fantastic question!
Here's a link on this topic at Springerlink (which means you really can't read it all without paying for it, so I'll summarize it). The article states that the melting point of oils and butters containing a mixture of fatty acids have unpredictable melting points but the presence of oleic acid in the butters reduces the melting point of a butter containing palmitic and stearic acid.
If you take something like shea butter that contains about 45% stearic acid (at 69˚C) and include about half oleic acid (13˚C), the melting point will be lower than the stearic acid alone (although we can't predict what that melting point might be). Cocoa butter with 1/3 oleic acid, 1/3 stearic acid, and 1/3 palmitic acid (62.9˚C) will have a higher melting point (38˚C) than the 45%-45% shea butter.
The melting points of our fatty acids increase with the increase in their molecular weights and saturation, so palmitic and stearic acid have higher melting points than oleic and linoleic acid (-5˚C). A combination of unsaturated, lower molecular weight fatty acids and saturated, higher molecular weight fatty acids will produce a butter with an unpredictable melting point - one with a higher melting point than the unsaturated fatty acids but lower than the saturated fatty acids.
Thanks again for the great question!