There are a few key reasons why it is important to dust pastries with flour before applying an egg wash:
Allows the egg wash to adhere properly
Applying an egg wash to unfloured pastry can cause the egg to soak into the dough rather than remaining on the surface. Lightly flouring the pastry first creates a barrier between the wet egg wash and the dough, allowing the egg to adhere to the surface and create an evenly glazed crust. The flour helps the egg wash stick to the dough rather than being absorbed.
Prevents sticking and tearing
If you apply egg wash directly onto dough, the high moisture content can cause the pastry to tear when moving or sticking to work surfaces. A light dusting of flour dries the exterior of the dough slightly so the egg wash can be applied smoothly without tearing or sticking. The flour creates a smooth, non-stick surface.
Allows patterns to show properly
When cutting patterns or shapes into pastry before baking, applying egg wash directly to the unfloured dough can cause the patterns to blur. Lightly flouring first keeps the edges crisp and defined when the egg wash is brushed over the top. This is especially important for delicate or intricate designs.
Creates a textured finish
The flour grains on the outside of the pastry give the baked good a lovely textured finish. When the egg wash is applied on top of the flour, it adheres the grains to the surface, creating a subtle crunchy texture and extra browning. Without flour, the egg wash alone can create a flat, one-dimensional crust.
Prevents over-browning
Using flour underneath egg wash prevents the exteriors of baked goods from browning too quickly in the oven. The flour partially blocks the egg proteins from causing excessive maillard browning. This allows the inside to cook through properly before the outside gets too dark.
Sets the wash
The proteins in the egg wash bond with the starches in the flour, helping it set up properly on the surface of the dough. This gives the egg wash more staying power and prevents it from sliding off heavier doughs or pastries with high moisture content like croissants.
Keeps layers distinct
For laminated and layered pastries like croissants, flouring between foldings prevents the buttery layers from merging together when the egg wash is applied on top. This keeps each layer separate and flaky in the final baked pastry.
Allows toppings to adhere
Any toppings like seeds, nuts, or decorations applied on top of egg wash can slide off or sink into the dough without a flour base layer. The flour gives the toppings something to adhere and stick to.
Provides crunch
The layer of flour underneath the egg forms a delicate crunchy crust as it bakes. This contrast of textures against the soft interior crumb is an enjoyable eating experience. The flour adds an element of crunch that egg wash alone cannot provide.
Balances moisture
Egg washes add a lot of extra moisture to the dough surface. For breads and pastries with higher hydration, this can make the crusts soggy. A light flour coating absorbs some of that excess moisture for a properly balanced exterior crust.
Makes it easier to handle
Flouring doughs and pastries before egg wash makes them less sticky and easier to pick up and maneuver as you prep them for baking. The flour minimizes the wetness and tackiness of the egg washed exterior.
Prevents shrinking and distortion
Wet egg wash can cause delicate doughs to distort or shrink as they bake. The flour layer provides insulation against that moisture, protecting the shape as it bakes for uniformity and better oven spring.
Lengthens shelf life
The double protection of flour and egg wash helps retard staling and extends the shelf life of baked goods. Flour slows down moisture migration and egg proteins delay starch crystallization, keeping pastries fresher longer.
Some examples of baked goods where flouring before egg wash is useful:
- Croissants
- Danishes
- Brioche
- Strudels
- Palmiers
- Tarts
- Scones
- Muffins
- Bread rolls
- Pies
- Galettes
- Cookies
- Choux pastry
- Cinnamon rolls
- Sweet rolls
- Braided breads
How to apply flour and egg wash
When flouring dough prior to egg wash, only a very light dusting is required – too much can leave a chalky taste. Follow these steps:
- Shape, fill or prepare pastries as desired.
- Dust the exterior very lightly with flour, tapping off any excess.
- Gently brush egg wash evenly over the surface.
- Apply any toppings as desired while egg wash is still wet.
- Bake as recipe directs until golden brown.
The flour and egg can be applied with pastry brushes, but paper towels or fingers work too. Let the egg wash dry slightly before baking for best results.
Conclusion
Applying a thin layer of flour before brushing on egg wash is an essential step for many baked goods. The flour provides a barrier layer that allows the egg wash to adhere properly without compromising the dough. This prevents sticking, gives a textured crunch, and protects the pastry shape. While optional for some recipes, flouring first is highly recommended with soft doughs and laminated pastries to maximize results.