By Harold McGee
Marshmallows were first made in France from the gummy root juice of the marsh mallow (Althaea officinalis), a weedy relative of the hollyhock; the confection was called pâte de Guimauve. The juice was mixed with eggs and sugar and then beaten to a foam. Today, marshmallows are made by combining a viscous protein solution, usually gelatin, with a sugar syrup concentrated to about the caramel stage, and whipping the mixture to incorporate air bubbles. The protein molecules collect in the bubble walls, and this reinforcement, together with the viscosity of the syrup, stabilizes the foam structure. The gelatin accounts for 2–3% of the mixture, and produces a somewhat elastic texture. Marshmallows made with egg whites are lighter and softer.