I did a search and spent ages reading through all the threads I could find, but there's SO much conflicting information on Meringue Buttercreams re food safety on here, that now I have less idea than when I started. Anyway, what I really would LOVE to know is:

How long would you leave a cake with Italian Meringue buttercream at room temperature? (Assuming the IMBC was made with real egg whites).

...anyone?

I only use pasteurized egg whites so I'm not sure I'll be of much help to you, but I have left mine out for several hours (say 6 or so) without issue. I would never leave it out overnight though.

The bottom line with meringue-based buttercreams is that they do not contain the sugar content to make them shelf-stable (in my opinion). I have read conflicting posts as well, but when dealing with egg products, it's better to err on the side of caution.

I always tell people to refrigerate unused portions and to let the cake come to room temp before serving.

Thanks for your comment tsal!

Such a shame that we can't use raw egg without a second thought like our mothers used to! I guess it is better to err on the side of caution...although sometimes I do wonder if we're really erring on the side of paranoia!!

Id still be interested to hear what others do with their IMBC.

I just buy the pasteurized egg whites.

I believe it's 24-48 hours. I prefer 24 hours. 2 weeks in the fridge. The egg whites are cooked with the simple syrup so there isn't as big of an issue with 'raw' eggs.

Decorated with or as a filling? In Australia I would have thought that your biggest issue would be with melting! However, I almost only use SMBC filling in my wedding cakes, and they can be out at room temp for 3 days before serving (I don't refridgerate any cake I make). I have never had an issue.