Using isomalt decorations on a cake can be a good way to incorporate glass-like elements, but it comes with some risks, including whether it’s a good idea to refrigerate isomalt at all.
In general, isomalt that’s on a cake can be refrigerated as long as the humidity is controlled when the cake is removed from the refrigerator.
Condensation that forms on a cake that’s taken from the fridge and placed in a humid or warmer room can soften the isomalt, and compromise the integrity of the cake design.
It can also cause the isomalt to become cloudy.
I did a cake with a lot of isomalt on it recently, and it made me tremendously nervous all week for a few reasons.
First, when you have a lot of isomalt on a cake you generally need to have fondant on it, which is going to form condensation when you take it out of the fridge.
And this one definitely needed to be refrigerated because of the fillings in it.
Condensation isn’t good for sugar, and they always say not to refrigerate isomalt.
The warnings range from “it will get sticky” to “it will dissolve immediately upon contact with the refrigerator air.”
So I had to think about when to decorate the cake with the isomalt as far as how long it could be out of the fridge and still stable enough for delivery. (I refrigerate everything before delivery so that they’re good and sturdy when they’re being moved around.)
Since I had appointments that day I wouldn’t be able to do it right before delivery, either.
As I thought about it all week, though, I was thinking that home refrigerators aren’t as humid as commercial fridges, so I thought that maybe it wouldn’t be as much of an issue if I did refrigerate the isomalt pieces.
To test this theory, I took two pieces and stuck them in the fridge overnight, which would be much longer than I’d need to have the decorated cake in the fridge.
The next morning they were perfectly fine.
Nothing had happened at all, and they hadn’t dissolved or changed shape.
I have to admit that I was slightly irked since I’d spent so much time worrying that they’d just crumble from being refrigerated.
So to punish the isomalt for not dissolving or melting, I put the two pieces in a bowl on my front porch while it was raining.
I figured that if it would hold up with that amount of water hanging around it would survive three hours in the fridge.
Sure enough, after an hour or so it was still fine.
I will also admit that I was pretty irritated that I’d spent all week worrying about the isomalt vs. humidity issue when it help up just fine.
But the delivery went fine and that’s all that matters…I guess.
So if you have to do this kind of thing, do a trial run to see how much abuse the isomalt, gumpaste, fondant, etc will take before you drive yourself crazy.
You might not have anything to worry about.