I made a frozen buttercream transfer on top of a cake and then covered the entire cake with the same buttercream. The recipe is half butter and half shortening. Do I have to keep this in the fridge?

The recipe that I use has both shortening and butter in it, and the pro that I know that uses it says that it doesn't need to be refrigerated. Did you use heavy cream in the recipe? That needs to be refrigerated.

If your fridge is cold enough, your buttercream can keep for months till you finish it. Please keep in a good tupperware container.

No I didn't put cream or milk in it. thanks.

Why American b/c's with small amounts of milk/cream and loads of powdered sugar don't require refrigeration:


Here's the science.

Water activity & microbial growth:
(Prolonging Bakery Product Life.)

http://tinyurl.com/6fbkcz

WJ Scott in 1953 first established that it was water activity, not water content that correlated with bacterial growth:

http://tinyurl.com/bmsato

Formulating for increased shelf life:
(Decreasing water activity results in hostile environment for bacteria.)

http://tinyurl.com/csu2b9

Shelf stable cream cheese icing:

http://www.cakecentral.com/cake-decorating-ftopict-582561-.html

HTH