No, it’s not a vision of one of the Catholic faithful, like the famous Virgin Mary grilled cheese sandwich, it’s a common problem that cake bakers like reader Nancy A. suffer from:
Dear Joe, is there anything you know that can be done about weeping cake batter? I swear it happens to me every time I make a cake, no matter how closely I follow the directions, and I follow them TO THE LETTER!! But something is going wrong and I’m hoping you know.
Indeed I do know what the problem is when a cake batter curdles and/or weeps: the dairy ingredients were too cold. Too often, cake recipes leave out that critical procedural detail. But what is a cake batter but an emulsion — a mixture, true, of flour and sugar, but also of tiny, suspended fat blobs, prevented from congealing by tiny bits of…stuff? For indeed that’s what emulsifiers are: miscellaneous molecular whatsits (frequently proteins of some description) that surround fat drops and keep them from clumping up.
In a cake batter those emulsifiers come primarily from the egg yolks, low-density lipoproteins (LDL’s) and high-density lipoproteins (HDL’s) that surround the fat molecules in the yolk, keeping the yolk itself emulsified. Turn them loose in a cake batter and they do pretty much the same thing — but only if they’re warm. Cold, they lose their flexibility and have a hard time keeping their fat droplets surrounded. The fat seizes the opportunity to join into masses — so does the nearby water — and you get a mixture full of clumps and liquid pools. Bake this and the result is short, dense layers with a very grainy texture.
So then, the answer to this is to bring the eggs and dairy up to room temperature, yes? Wrong. You want your eggs and dairy warmer than room temperature to make your emulsifiers maximally effective. 85 degrees Fahrenheit is about perfect. How to do that? Well, I’ll show you…