To create dark, burnished crusts on their loaves, professional bakers brush milk, egg, or water onto the surface of the risen dough before baking. Each of these washes enhances browning by triggering the Maillard reaction, in which carbohydrates and proteins recombine under heat to produce new flavor compounds (and deeper color). But each does it a different way for a slightly different finish. Milk’s naturally occurring sugars work in conjunction with proteins from the flour. In an egg wash, the egg itself contains proteins necessary for browning. Water, on the other hand, causes some of the starches on the surface of the dough to break down into glucose. Once the water evaporates, the glucose interacts with the flour proteins to create browning.
In the test kitchen, we prefer plainer washes like water and milk for sandwich bread and dinner rolls, and reserve egg washes for richer, egg-based breads like challah and brioche and pie crust. Which wash you choose is up to you, but here’s what to expect in the finish.
| WASH TYPE | BROWNING/FINISH | FAVORITE USES || --- | --- | --- || Water | Decent browning: little shine | Sandwich bread, dinner rolls || Milk | Good browning; moderately shiny, satiny finish; subtle sweetness | Sandwich bread, dinner rolls || Whole egg | Good browning; moderately shiny, satiny finish; subtle egg taste | Challah, brioche, pie crust || Egg white | Very good browning; moderately shiny, satiny finish; mild egg flavor | Challah, brioche, pie crust || Egg yolk | Very good browning; extremely shiny (almost shellacked in appearance): no egg flavor | Challah, brioche, pie crust |
