Egg wash is a mixture of beaten eggs and liquid (usually water or milk) which is brushed onto baked goods like pastries before cooking. It adds shine and color and helps keep the edges together. When you see this term used in a recipe or cooking directions, knowing why and how to use it will help you get the best results.
The golden, shiny glaze on the surface of a pie crust was probably created by brushing it with egg wash before baking. Egg wash helps give a golden brown sheen to soft bread like dinner rolls, danish pastry, cinnamon rolls, brioche, and challah.
Egg wash can also be used as a sort of glue to secure two edges of pastry together, as when making filled pastries, empanadas, or en croute (in crust) recipes. This works because of the protein in the egg coagulates when it's cooked, forming a stiff bond that isn't reversible.
If are sprinkling your pastry or bread with granulated sugar or spices, brushing it with egg wash first will help the granules stick to the surface instead of spilling off.
This nature of egg wash to stick things together has its drawbacks. You need to be careful with egg wash when you're working with puff pastry, because if it drips onto the edges of the pastry, it can glue the layers together, thus preventing the pastry from puffing while it bakes.
Use these ingredients and procedure for an egg wash:
- Crack an egg into a bowl and beat it thoroughly with a fork.
- Add two tablespoons of water and a pinch of salt. Stir until combined.
- Brush the egg wash onto the surface of your item.
You can use less liquid for a darker egg wash, or substitute milk or cream for the water. Alternately, some people use pure egg and don't even bother adding any liquid. This will produce a very dark shine.
Egg wash can be used on other foods besides just pastry. Duchesse potatoes are usually brushed with egg wash before baking.
Safety and Cleanup
You need to wash your pastry brush with cold water immediately after applying an egg wash, as hot water will coagulate the egg wash and the bristles will stick together. After the cold water rinse, you can then wash and sanitize the brush in hot water. This is particularly a problem if your brush is made with natural bristles. A silicone pastry brush is preferable for applying egg wash. It is easier to clean, the bristles can't become glued together, and the silicone bristles don't absorb odors or fats the way natural bristles do. Nor do they shed their bristles the way natural bristle brushes do.
Egg wash is made with raw egg, and as such it carries a risk of transmitting Salmonella bacteria. Baking will kill the bacteria and your item will be safe, but you should never apply egg wash to an item that will not be baked. The dishes and brush used for making and applying egg wash must be thoroughly cleaned before being used for other food preparation tasks.