Improper stirring sponge cake is a fluffy snack made by using the foaming characteristics of protein, filling a large amount of air into the egg liquid and adding flour to bake. It is named because its structure is similar to porous sponge. It is also called foam cake abroad and vegetarian cake at home. In the process of making cakes, the globulin in protein reduces the surface tension and increases the viscosity of protein by high-speed stirring. Because the components with high viscosity contribute to the formation of foam in the early stage, they can be quickly pumped into the air to form foam. Globulin and other protein in protein are slightly denatured due to the mechanical action of stirring. Denatured protein molecules can condense into a layer of skin, forming a very strong film to surround the mixed air. At the same time, due to the surface tension, protein foam shrinks and becomes spherical. In addition, the protein colloid is sticky, and the added flour raw material adheres around the protein foam, which makes the foam very stable and can keep the mixed gas. During the heating process, the gas in the foam expands when heated, which makes the product loose and porous and has certain elasticity and toughness.