The Science Behind Pastry: Sweet Shortcrust Pastry and Peach & Almond Filling

Flour, butter, water and eggs. These ingredients, mixed in different ways and in different proportions, can produce a myriad of baked goods – bread, doughnuts, scones, eclairs, tart shells, pie shells or croissants… the list goes on and on. Have you ever wondered how the same ingredients produce goods of such diverse texture and shape? The secret lies largely in a protein substance called gluten.

Gluten is formed when proteins (from the flour) cling together and form strands. These strands are what makes dough elastic, and helps it keep it’s shape. Thankfully, gluten formation doesn’t happen by magic – we know it is caused by adding liquid to the proteins or by working them through kneading or stirring. All dough needs at least some gluten, although some more than others.

Bread requires a very elastic dough with a lot of gluten (hence all the kneading). When making pastry however (as we’ll be doing), the gluten content must be limited in order to keep our produce light and airy. Pastry gets its texture not only from gluten strands, but also from steam that forms when the butter melts and the liquids in the dough evaporates. Unfortunately this means that pastry dough is a lot harder to roll out and shape, because it is less elastic and more likely to break or crumble. But don’t despair, if we follow the steps carefully we will end up with delicious pastry.

Let’s make some sweet shortcrust pastry and see if we can apply all of this.

Sweet Shortcrust Pastry

We’ll need the following ingredients:
175g plain flour
100g butter (it must be cold, not at room temperature)
25g icing sugar
1 large egg yolk
1 tbsp ice cold water

We will also need:
a food processor
a rolling pin
a 23cm tart tin
baking beans

1. Use a food processor to mix the flour, icing sugar and butter (very briefly) until it resembles bread crumbs (this coats the butter in flour, keeping the liquid inside and preventing gluten formation).

2. Add the water and egg yolk, and process just until the mixture sticks together in a ball. Watch the food processor carefully – you don’t want to over-mix.

3. Remove the dough from the food processor and knead only two or three times until it forms a smooth ball. Too much kneading will form tough gluten strands, and our pastry will be rubbery. If the pastry is too warm and soft, chill it in the fridge for 15 minutes. Don’t add more flour, this will also result in gluten strands.
4. Grease your tart tin. Cut a piece of parchment paper bigger than the tart tin, and dust it with flour. Carefully roll out your dough on the parchment paper in a circle, until it is a few centimeters bigger than the tart tin. Again work gently, to prevent the dough from toughening.
5. When you are done, you can flip the parchment paper and gently transfer the rolled out dough to the tart tin. Carefully press the pastry into the tart tin, letting the excess hang lightly over the rim. Prick the base with a fork (to let out air so that the base doesn’t ‘balloon’ when baking).
6. Chill the pastry-lined tin in the fridge for 30 minutes. This is an important step that will solidify the butter, controlling the gluten and steam formation during baking. Preheat your oven to 200°C.
7. When the 30 minutes have passed, it is time to blind bake your pastry shell. Blind baking means baking the pastry shell before it has been filled. This makes the pastry crisp and brown and prevents it from becoming soggy later. Line the pastry case with tin foil, and fill it with baking beans (or alternately kidney beans).

8. Bake for 12 minutes, then lift out the foil and baking beans, and trim off the excess pastry from the sides. Bake the shell for another 10-12 minutes, or until it is dry and pale golden. Set it aside to cool while you make your filling.

Peach and Almond Filling

To make the filling you will need:
5 peaches
200ml dessert wine
100g caster sugar
Juice of 1 lemon
175g ground almonds
150g butter, at room temperature
100g caster sugar
3 large eggs, beaten
75g plain flour

1. Preheat the oven to 180°C.
2. Cut the peaches into wedges and poach them in a saucepan with the wine, 100g caster sugar and lemon juice for about 10 minutes.

3. While the peaches are poaching, cream the butter with 100g caster sugar until the mixture is pale. Gradually add the eggs, then fold in the flour and ground almonds.
4. Tip this filling into the tart tin, and level it out with a spatula. Arrange the poached peaches on top, and bake the tart for about 30 minutes or until it is golden brown.
6. Reduce the wine mixture to about 6 tbsp liquid, and brush the warm tart with some of the syrup.

If you’ve followed all the instructions and worked gently enough with your pastry dough, your tart will hold together but still be slightly flaky and full of flavour. Now it’s time to enjoy it will your family or friends. It’s definitely worth all the effort, don’t you think? There’s nothing quite like a freshly baked tart.

Download print-friendly recipe.