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Sugar in the presence of heat
Hi - I’m hoping someone can help me understand what’s going on. I make what is termed emulsified sugar scrubs utilizing coconut oil, sunflower oil, shea butter, stearic acid for a little density, and Polysorbate 20, which helps the product to rinses clean when the client uses it in the shower.
To make the scrub, I basically heat the oil mixture and add the sugar. I notice that when I add the sugar when the oils are warm, the scrub is very soft and requires a higher percentage of ingredients to get the firmness I’m looking for. When I add the sugar, at let’s say, 150 degrees, I get a semi-firm scrub using a lower percentage of ingredients.
The only thing I can figure out is that something happens to the sugar when it comes in contact with hotter oils which results in a firmer product. I hope I’ve explained this sufficiently.
Can anyone chime in?
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3 Replies
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It’s not the sugar reacting in any way.
When the sugar is added to hot oil, the coconut oil, shea butter, and stearic acid are melted. As the mixture cools, those solid ingredients start to crystallize. The sugar crystals are already present, so the wax matrix that slowly forms as your batch cools is connected to them, and you get a firm product.
But, if you allow the mixture to cool before you add the sugar crystals, the wax matrix forms without them. Once the wax matrix is formed, it doesn’t re-form unless you heat it back up again past it’s melt point. What’s worse, you’re actually breaking the matrix structure down by mixing it after it cools, in order to get the sugar in. This will give you the lower viscosity that you’re seeing.
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An obvious “thickening effect” now that I think about it
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Great explanation! Thank you so much Bobzchemist. This was really puzzling. Now I’ll read up on crystallization for a deeper understanding. Your contributions to this forum are invaluable!
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