Does anyone else LOVE the smell of meringue powder? Mmmmmm. I'd rather smell my buttercream than eat it.....that came out strange.
Anyways, I was wondering...what exactly does meringue powder do for my icing? Does it help it to crust over? (That's my best guess...)
I think it stabilizes the icing, particularly in hot or humid weather. I know that my icing tends to slide off the cake in hot weather if I don't use the meringue powder.
It is (if I remember correctly) the powdered sugar that causes the crusting. I know that a milk/powdered sugar glaze crusts really quickly.
Meringue powder does two things: (1) it stabilizes the icing, so it will hold up better in hot/humid weather, and (2) though the icing can crust without it, adding MP will make the icing crust faster and firmer, so it's great to add when you are using mats or presses to imprint patterns into buttercream, or want to make dried BC flowers.
So, I don't add MP all the time, but in hot/humid weather, for any outdoor reception, or when imprinting designs I do, about 2 T MP per 2 lb powdered sugar (a little more when making flowers). Oh, I also always add it to cream cheese buttercream when used on a wedding cake since it tends be softer and more apt to slide off the cake.
Ooooh! I'll remember that. Next time I run out of it, I won't freak out and run to the store.