1. baking process: ① baking time and temperature are not enough, not baked. ② baking temperature is too high, resulting in the surface quickly baked, the internal uncooked removed.
2. When mixing the egg yolks: the yolks are not evenly mixed, the fat is not fully emulsified, and there are lumps or particles.
3. During mixing: the egg whites and egg yolks were defoamed during mixing, resulting in a cake that did not rise, and the interior of the baked cake was just soggy and inelastic.
4. Out of the oven: ① did not shake the cake body, so that the center of the heat out. The water vapor can't be dispersed, and it stays in the cake, making the middle wet and sticky.
5. Problems with the recipe itself: too much liquid, too little flour.