Pie and Tart Crusts.
Two crusts from the same recipe: one flaky and tender, one tough and shrunk down the sides of the tin. The difference was two tablespoons of water and a warm kitchen.
Pastry is flour, fat and a little water, about 3 : 2 : 1 by weight (XXIII.10). How the fat is mixed in decides the type. For flaky pie crust, cold butter or lard is cut into the flour until the pieces are the size of peas or flattened flakes, then just enough ice water is added to hold the dough together. In the oven the fat pieces melt, the water in them (butter is about 16 % water, IX.5) turns to steam and lifts the dough into layers: flaky. For shortcrust (pâte brisée, and sweeter pâte sucrée and sablée for tarts), the fat is rubbed in finely so it coats the flour and the crust is tender and crumbly rather than layered.
Two things ruin both. Too much water, or too much working once water is in, develops gluten: the crust is tough, and as the stretched gluten relaxes in the oven it shrinks down the sides of the tin. Warm fat smears into the flour instead of staying in pieces: the crust is greasy and mealy, not flaky. So pastry is made cold, quickly, with water added a spoonful at a time, and rested in the fridge for at least 30 minutes before rolling and again before baking, which relaxes the gluten and firms the fat. The workshop makes a crust.
Below: teaching indices for a pie crust from the water (as a percentage of flour), the minutes of working after the water goes in, and the butter's temperature: toughness from gluten, and flakiness from fat that stays solid in pieces (course butter melting curve, IX.2).
- Make flaky and short crusts.
- Keep fat cold and in pieces.
- Add the least water and work.
- Rest and blind-bake to stop shrinking.
Cold, quick, little water, then rest
On the teaching indices, 25 % water worked for a minute gives a toughness of 0.27; 40 % water worked three minutes gives 1.38 — a crust that will shrink. Butter at 6 °C is still about 0.66 solid and stays in pieces; at 18 °C only 0.21, and smears. A food processor pulsed briefly, frozen grated butter, ice water and a cool kitchen all help; lard and shortening, which stay plastic over a wider range, are more forgiving than butter but less flavourful.
Method for a flaky crust (one 23 cm pie): 200 g flour and a pinch of salt; 130 g cold butter cut in until pea-sized; 50–60 g ice water sprinkled in a spoonful at a time, tossing, until a squeezed handful holds; press into a disc without kneading, wrap, chill 30 minutes; roll from the centre outwards, turning, to 3 mm; lift into the tin without stretching; chill again 30 minutes. Blind-bake for a wet filling: line with paper and weights, bake at 200 °C for 20 minutes, remove weights and bake 5–10 minutes more until dry. Brush the base with egg white to seal it against soggy fillings.
Make two small crusts from one recipe: one with 25 % ice water and brief mixing, one with 40 % water kneaded for three minutes. Blind-bake both and compare shrinkage and texture.
Terms
- Flaky crust
- Pastry with fat in pieces that steam into layers.
- Shortcrust
- Pastry with fat rubbed in finely: tender and crumbly.
- Blind baking
- Baking an empty crust weighted, before the filling.
- Shrinkage
- A crust pulling back as stretched gluten relaxes.
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.