I've only ever made French meringue prior to this, and I've only ever used whole, separated eggs.
In this case, I used egg whites out of a carton (probably should note they were only a few weeks shy of their expiration date). I know fresher whites whip up better, but I definitely got these to soft/slightly stiff peaks when I whipped the whites on their own. However, when I added the sugar syrup the meringue turned liquidy pretty quickly. I kept it whipping for a bit but the texture remained pretty liquidy (I did use some cream of tartar to help stabilize, but to no avail, apparently).
I'm wondering which, if any, of the following is the likely culprit:
- is there any general detriment to using the whites from the carton?
- was it simply the lack of freshness? (I would be surprised if it was either just because the whites did whip up pretty nicely before I added the sugar)
- could the syrup have been too hot or in some other way caused the whites to break down?
- could I have overwhipped the whites before adding the sugar? the peaks didn't seem to be too stiff before that point, but I suppose it's possible
- something else?