Lack of expansion agent: When baking a cake, heat will expand the air inside the cake, thus increasing the size of the cake. However, if the air inside the cake does not have enough expansion agent to maintain this expansion state, the cake will shrink during baking.
Improper time and temperature: The way of microwave heating cakes is different from the traditional oven, so special attention should be paid to the baking time and temperature. If the baking time is too long or the temperature is too high, the cake may be overcooked, resulting in shrinkage.
Lack of structural support: Cake needs enough structural support to keep its shape during baking. If the cake formula lacks some structural supporting materials, such as flour or protein, it will easily shrink.
Uneven heating: Sometimes microwave heating may not be uniform enough, causing some parts of the cake to overheat while others are not cooked, which will also cause the cake to shrink.
To sum up, in order to prevent the cake from shrinking in the microwave oven, attention should be paid to the quantity and type of expansion agent in the formula, the control of heating time and temperature, the addition of structural support materials and the uniformity of heating. It is suggested that baking cakes in the oven will be more stable.