Wednesday, April 11, 2012
Using thickeners in our products
The various emollients we use contain fatty acids, and those fatty acids have different solidification temperatures. Let's say we use something like shea butter with cetyl alcohol in our product. Shea butter contains a number of different fatty acids with different melting points - stearic acid stays solid until about 69.6˚C, palmitic acid at 62.9˚C, oleic acid at 13˚C, and linoleic acid at -5˚C. This means that stearic acid is still going to be liquidy at 70˚C, our heat and hold temperature, but it'll start to solidify when we're still mixing our ingredients. The palmitic acid will start to solidify around 63˚C. The cetyl alcohol will be melty until about 49˚C, and so on. So when our product is in the heat and hold phase, it's not going to be the true thickness of the end product.
Think about coconut oil, which might be listed as being coconut oil 76, which means it melts at 76˚C. In the summer, this stuff turns liquid in my workshop! If you find the product coconut oil 92, it means that the fatty acid profile has been altered to include more fatty acids that have a higher melting point.
And note, when you choose another thickener, there will be differences in when that fatty alcohol or fatty acid solidifies. Cetearyl and cetyl alcohol melt around 49˚C, cetyl esters anywhere from 43˚C to 47˚C, and stearic acid around 69˚C. Big differences, eh? And it's noted that cetyl esters can take up to two days to come to the final thickness.
Why does my butter go grainy?