Angel food cake
A fat-free egg-white foam cake that depends on an ungreased tin to climb, and is cooled upside down because its own weight would otherwise collapse it.
Also called angel cake (UK) — In Britain the name also refers to a layered pastel sponge, which is a different cake., angel food (US)
Angel food cake is an egg-white foam with sugar and a small amount of flour, and no fat at all. Every rule attached to it follows from those two facts.
NO FAT MEANS THE FOAM IS FRAGILE AND ESSENTIAL. Fat destabilises an egg-white foam by interfering with the protein film around each bubble, which is why a trace of yolk or a greasy bowl prevents the whites whipping properly. There is no butter, no oil and no chemical leavener to compensate: the air whipped into the whites is the entire leavening.
THE TIN IS UNGREASED ON PURPOSE. The batter climbs by gripping the sides of the tin as it expands; a greased tin gives it nothing to hold and the cake rises less and slumps. This is the opposite of the instruction for nearly every other cake on this site, and it is the most commonly ignored one.
IT IS COOLED UPSIDE DOWN for the same structural reason. A hot fat-free foam cake has very little strength while its starch and protein finish setting, and left the right way up it compresses under its own weight. Inverting it puts the structure in tension until it has set.
CREAM OF TARTAR IS FUNCTIONAL. A little acid lowers the pH of the whites, which stabilises the foam and makes it more tolerant of over-whipping. It is not a flavouring and leaving it out makes the foam less forgiving.
What it should be like
- Crumb texture
- Very open, white and cottony; visibly a set foam
- Structure
- Extremely light and fragile until fully cooled
- Tenderness
- Chewy rather than short — there is no fat to shorten it
Where it comes from
Professional consensus
Agreed by professional bakers and baking-science texts, with an accepted mechanism, though not isolated by controlled experiment.
An American cake associated with the period when cheap refined sugar, fine flour and reliable tinned bakeware became available together, which is what makes a fat-free foam cake practical at all.
More in baking history and culture.
Why it shrinks, sticks or collapses
Shrinking away from the tin as it cools is usually a cake that was cooled the right way up, or turned out too early. Both let the structure compress before it has set.
Sticking is the intended behaviour and only becomes a problem at the end: the cake is released with a knife rather than by greasing the tin in advance, because greasing it costs the rise the cake exists for.
A cake that never rose has almost always lost its foam. Any fat at all — yolk in the whites, residue in the bowl, a plastic bowl that has held butter — will do it, and so will folding the flour in with a heavy hand after the foam was correctly built.
Related
Part of
A fat-free egg-white foam, which is the family’s aeration mechanism taken to its extreme.
Things that go wrong
The cake is dense and did not rise
A foam that was never built, or was knocked out, leaves nothing else to raise this cake.
A fat-free foam cooled the wrong way up compresses under its own weight.
Meringue is weeping, chewy or will not whip
The batter IS an egg-white foam, so the meringue model’s causes — fat in the whites, sugar that never dissolved — are this cake’s causes.
A tall tube tin bakes unevenly if the oven does.
What this product needs done
Aeration
An egg-white foam and nothing else. There is no fat and no chemical leavener to fall back on.
Structure building
Egg-white protein setting, supported by a small quantity of starch.
pH modification
A little acid stabilises the foam and makes it tolerant of over-whipping.
Characteristic ingredients
The cake is a set egg-white foam.
Stabilises the foam and must dissolve into it.
Acid that stabilises the whites and makes them tolerant of over-whipping.
A small quantity of weak flour, for as little structure as will do.
Techniques involved
An egg-white foam, and there is nothing else.
The flour goes in without knocking the foam down.