Choux pastry and steam
Choux has no yeast and no baking powder. You cook flour into a paste with water and butter, beat in eggs, then bake hot. The water turns to steam and inflates the shell while the eggs and starch set.
Cook the paste, cool it, add eggs
Stirring the flour paste over heat gelatinizes the starch so it can hold lots of liquid, and it drives off some water so the paste can take more egg. Cool it a bit first, or the eggs start to cook.
Test yourself
Questions from the interactive lesson, with the answer and the why.
What makes a choux puff expand in the oven?
Steam from the water in the paste. Water turns to steam in the hot oven and inflates the stretchy paste.
True or false: Choux pastry needs baking powder to puff, because it has no other leavener.
False. Steam does the lifting. Choux needs no chemical leavener.
What went wrong? You beat eggs into the paste right off the burner. The mix turns streaky and lumpy, and the shells bake up flat.
The paste was hot enough to start cooking the eggs. Cooked egg bits cannot stretch or blend, so the shell loses lift.
Fill the blank: A choux puff inflates because the water in the paste turns to ___.
A choux puff inflates because the water in the paste turns to steam. Hot oven heat turns the paste's water into steam that expands the shell.
Choux puffs rose beautifully, then sagged soon after leaving the oven. What is the likely cause?
The walls had not dried and set before the puffs came out. Wet, soft walls can't hold their shape once the steam inside cools.