The sponge cake is made of low-gluten flour. Because the low-gluten flour has no strength, the cake made of it is particularly soft, bulky and flat. Low-gluten flour is similar to cake flour and pastry flour in daily life, but in addition to low-gluten flour, cake flour also contains wheat starch and emulsifier. Low-gluten flour refers to flour with water content 13.8% and coarse protein below 9.5%, which has the functions of nourishing heart, tonifying kidney, removing heat and quenching thirst.
High-gluten flour, with protein content of 1 1.5% or more, has the strongest gluten. It is used to make bread, jiaozi, pizza, puffs, fried dough sticks, thousand-layer cakes and other snacks that need to rely on strong elasticity and ductility to wrap bubbles and oil layers in order to form a loose structure.