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Exponentially Upping the Flakes in Pastry

By Cook's Illustrated Published January 2012

Puff pastry, croissants, and flaky pastry all rely on a mathematical phenomenon to achieve their many-layered structure. We cracked the code.

Puff pastry, croissants (see related recipe), and the flaky pastry we created for our vegetable tart recipes (see related recipes) all rely on a mathematical phenomenon to achieve their many-layered structure. These so-called laminated pastries, which are made up of alternating layers of dough and fat, are created by repeatedly rolling and folding the dough over itself, typically in thirds (like a business letter). Each set of folds is called a turn, and with each turn the number of layers increases exponentially rather than linearly. Thus, the first turn gives three (31) layers, the next nine (3 x 3, or 32), then 27 (3 x 3 x 3, or 33), then 81, and so on. Just eight turns (in our tests, the highest number possible before the layers got so thin that they melded together) create an astonishing 6,561 layers.

FOLD, ROTATE 90°, ROLL

FIRST TURN

Creates three layers

SECOND TURN

Creates nine layers

THIRD TURN

Creates 27 layers

Done in 281 ms! 61.385 KiB - 7.5% = 56.776 KiB