I made a chocolate cake that was soaked in an alcohol simple syrup filled with mousse. I also gave the cake a crumb coat with the mousse. I then covered it with fondant. Tis is not the first time but my cake started to leak liquid and the fondant started to thin out and get droopy...anyone know why?? This is not the first time.... I'm not sure if it is the mousse or the simple syrup...I'm not over soaking it and I'm not refridgerating it either...of course I put the left overs in the fridge...anyone..please help!
It probably is too much moisture seeping out of the cake and coming into contact with the fondant. It melts the fondant from the backside and creates a sugar syrup that leaks out and erodes the fondant in spots where it's thinner.
If this is a typical sponge cake, you just can't soak it with liquid and expect it to hold that liquid indefinitely. The more soaked it is, the less time you have before it creates problems.
A simple syrup is usually applied with a pastry brush LIGHTLY, dabbing gently over the cut surface of the cake. It's not used to "soak".
I think it's the mousse. If it's made with heavy whipping cream, the cream will break down and get watery. This happens to me all the time when I make a trifle with heavy whipping cream and I don't stabilize it with anything. I think you are ok with the simple syrup as long as you use it sparingly and don't go crazy with it. A lot of people use simple syrups and cover in fondant with no issues. Use buttercream instead of mousse on the outside and you should be ok.
Fortunately have not had problems with a whipped filling...I just make sure my dam is good and thick around the cake to hold it in. And I put a thin layer of BC over the top so the filling won't soak into the cake as much.
I don't use simple syrup...sometimes a light coating of Kaluah on chocolate cake...but very light...not soaking.
Can you make your simple syrup thicker - boil it longer?
The moisture in you mousse melted the fondant. I promise. You can do the same thing next time and either A) coat with buttercream instead or B) place a layer of buttercream over the mousse to keep them separate.