Does it really have a considerable advantage on preservation to heat and hold both phases for 20 minutes? It would kill "some non-endospore forming bacteria".
But if your water and raw ingredient quality is good, have Good Manufacturing Practices, adequate broad spectrum preservatives and take the hurdle approach, is that really worth the time and energy?
Comments
In some emulsifiers (nonionics come to mind), the product was held at heat and mixed AFTER the oil and water phases were combined. It was felt to decrease the size of the micelles, leading to a more stable emulsion. It is a valid technique in some cases.
Thanks a lot for your answers!
I totally agree with you. In a time where we are supposed to save energy instead of waste it, I think it's useless and also time consuming.
I got confused because it is still advised on the new Making Skincare site for microbial reasons.
So the original purpose was post-emulsification heating for emulsion stability for some emulsifiers like non-ionics. Makes a lot more sense.
Erratum (in first post): instead of 'both phases', I meant the water phase only.