In shortcrust pastry, the butter is evenly distributed through the dough is small pieces. The function of
the butter is to separate the starch granules from each other, preventing them from sticking together
and forming a compact mass, which keeps the pastry flaky.
Starch gelatinisation during heating is minimal due to the small quantity of water present, which helps
keep the pastry dry and crisp. The dough is usually left to sit before it is cooked, to aid the distribution
of water so that it can more easily penetrate the starch granules during cooking. The weak network of
coagulated flour proteins that forms during cooking acts to hold the swollen starch granules together,
giving the pastry some sort of structure.
As the cake cools, the butter will solidify, and this helps the starch grains stay stuck together even
though the protein network is weak, by acting as a sort of glue. Cold pastry is therefore less flaky than
hot because the butter has solidified. Tarts are usually removed from their cases when they have been
left to cool, since this means their structure holds together better.
When preparing puff pastry, the butter is added to the dough as a single block and the butter is then
evenly distributed throughout the dough layers by repeatedly folding, rolling and refrigerated. If the
procedure is carefully followed, the resulting pastry will be made up of as many as 240 separate layers
or dough, where each layer is separated from each other by a thin layer of butter. Puff pastry is always
prepared on a marble surface to keep it cold, and the dough is refrigerated as much as possible, to
ensure that the butter is kept as solid as possible.
The constant folding process acts to finely distribute the butter through the structure, and also helps
incorporate air into the pastry, making the resulting dough lighter and more airy. However, the process
of preparing puff pastry will also develop the flour proteins present to form gluten, which would cause