Sponge and Chiffon Cakes.
A chiffon cake has no butter to cream and often little baking powder. Its height is the air beaten into egg whites — and lost, stroke by stroke, in careless folding.
Sponge cakes are leavened by egg foams. A genoise whips whole eggs and sugar, warmed to about 40 °C so the sugar dissolves and the foam grows, until the batter falls from the whisk in a ribbon; flour is folded in, sometimes a little melted butter. A separated sponge or a chiffon cake makes a yolk batter — yolks, sugar, liquid and, for chiffon, oil, which keeps it moist and soft even cold — and a meringue of whites and sugar (X.6), then folds the two together. In the oven the air cells expand as they heat and water turns to steam (XVII.9), and the egg and flour set around them.
Every stage either keeps air or loses it. Underwhipped whites hold too little; overwhipped whites turn dry and grainy and break into lumps when folded (X.6). Folding — cutting down through the middle with a spatula and lifting the batter over itself while turning the bowl — combines meringue and batter with the fewest strokes; stirring knocks out the air. Fat (a trace of yolk in the whites, or butter added carelessly) collapses foams. And chiffon, set in an ungreased tube pan, is cooled upside down so its delicate structure hangs rather than sinks. The workshop whips and folds.
Below: the stiffness and air (overrun) of egg whites whipped with sugar for the minutes you choose (course foam model, X.6), and a teaching estimate of the air left in the batter after the folding strokes you choose.
- Whip egg foams for cakes.
- Fold without losing air.
- Make chiffon and genoise.
- Prevent collapse.
Whip to glossy peaks, fold in few strokes
On the teaching estimate, 30 folding strokes keep about 0.74 of the air and 80 strokes only 0.45. So the meringue is folded in stages: a third stirred in vigorously to lighten the batter, the rest folded gently in two additions, stopping as soon as no streaks of white remain. Whites are whipped to firm, glossy peaks that bend slightly at the tip — not dry and grainy, which fold badly — with the sugar added gradually once they are foamy, and a little acid (cream of tartar or lemon) to stabilise them (X.6).
Chiffon (戚风): whisk 5 yolks with 30 g sugar, 60 g oil and 80 g milk or water, then 90 g cake flour; whip 5 whites with a pinch of cream of tartar and 60 g sugar to firm peaks; fold in three stages; pour into an ungreased tube pan, tap once, bake at about 160 °C for 45–55 minutes until it springs back; invert at once and cool completely before unmoulding. Genoise: warm 4 eggs and 120 g sugar over a water bath to 40 °C, whip to a thick ribbon (8–10 minutes), fold in 120 g sifted flour, then 30 g warm melted butter, bake at 180 °C. Both are baked as soon as they are mixed, before the foam drains.
Fold a chiffon batter: count your strokes, and compare with a second batch stirred instead of folded. Measure the height of each cake.
Terms
- Genoise
- A sponge of warmed, whipped whole eggs and sugar.
- Chiffon
- An oil-and-yolk batter folded with meringue.
- Folding
- Combining a foam and batter with gentle lifting strokes.
- Ribbon stage
- Whipped eggs thick enough to fall in a ribbon.
Sources
- A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
- H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.