Albumen powder
dried egg white
Albumen powder is dried egg white. It is produced by spray-drying liquid white, which removes the water while leaving the protein structure intact.
It is used two ways. Reconstituted with water at roughly one part powder to seven or eight parts water, it replaces fresh white. Added dry to fresh whites, it strengthens a meringue: it raises the protein content without adding water, so the foam comes out denser and more stable. That is particularly valued in macaron work and royal icing.
The practical advantages are long storage without refrigeration, accurate dosing, and microbiological safety: commercial albumen is pasteurised, which makes it suitable for preparations that are never cooked.
When reconstituting, add the powder to the water gradually while stirring and let it stand — undissolved albumen leaves grains that whipping will not disperse.