为什么蒸蛋糕会回缩呢？

蒸蛋糕是一道受欢迎的甜品，在制作过程中，蛋糕会膨胀变大，但在蒸煮完成后，很多人发现蛋糕会回缩，变得比蒸前小了许多。这是因为蒸蛋糕的制作过程中发生了一系列的理化变化。

首先，蛋糕中的面粉含有一种叫做谷蛋白的成分。当谷蛋白和水接触时，会吸收水分并形成黏稠状物质。在蒸煮过程中，高温会使谷蛋白中的淀粉分子开始变得黏稠，形成一种网状结构。这个结构能够在蒸发的蒸汽压力下支撑着蛋糕的体积。

然而，蒸煮完成后，蛋糕中的谷蛋白会因为温度的下降而失去黏性，从而导致网状结构的破裂。这时候，蛋糕就会缩回原来的尺寸，并且变得更加紧密。此外，蛋糕中还含有蛋白质，它们也会在高温下发生变性，使蛋糕更加松软。但当温度降低时，蛋白质会恢复原来的状态，导致蛋糕回缩。

除了谷蛋白和蛋白质的影响外，还有其他因素可能导致蒸蛋糕回缩。其中一个重要的因素是蛋糕中的二氧化碳产生与释放。在蒸煮过程中，面粉中的淀粉会被分解成葡萄糖，并被酵母菌转化为二氧化碳和酒精。这些气泡会在蒸发过程中逐渐增大，使蛋糕膨胀。然而，当蒸煮结束时，蛋糕中的二氧化碳会逐渐释放，导致蛋糕回缩。

另外，蒸蛋糕的回缩还可能与蛋糕的材料比例有关。如果蛋糕中的蛋白质过多，会导致蛋糕过于松软，容易回缩。相反，如果蛋白质太少，蛋糕会过于紧密，也容易回缩。因此，在制作蒸蛋糕时，合理的材料比例非常重要。

总而言之，蒸蛋糕回缩是由于面粉中的谷蛋白和蛋白质在高温下发生的理化变化以及二氧化碳的产生与释放所导致的。此外，蛋糕的材料比例也会对蛋糕的回缩产生影响。要制作一款完美的蒸蛋糕，我们需要准确地掌握这些原理，并合理调整制作过程中的各项因素。

Why do steamed cakes shrink?

Steamed cakes are a popular dessert, and during the cooking process, the cake expands and becomes larger. However, many people have noticed that the cake shrinks and becomes much smaller after steaming. This is because a series of physical and chemical changes occur during the making of a steamed cake.

First, the flour used in the cake contains a component called gluten. When gluten comes in contact with water, it absorbs the moisture and forms a sticky substance. During the steaming process, the high temperature causes the starch molecules in gluten to become sticky, forming a web-like structure. This structure can support the volume of the cake under the pressure of evaporating steam.

However, after steaming is complete, the gluten in the cake loses its stickiness due to the decrease in temperature, leading to the rupture of the web-like structure. At this point, the cake shrinks back to its original size and becomes denser. Additionally, the cake also contains proteins that undergo denaturation at high temperatures, making the cake softer. But as the temperature decreases, the proteins return to their original state, causing the cake to shrink.

In addition to the effects of gluten and proteins, there are other factors that may contribute to the shrinking of a steamed cake. One important factor is the generation and release of carbon dioxide in the cake. During the steaming process, the starch in the flour is broken down into glucose, which is then converted into carbon dioxide and alcohol by yeast. These bubbles gradually increase in size during evaporation, causing the cake to expand. However, when steaming is finished, the carbon dioxide in the cake gradually releases, resulting in shrinkage.

Furthermore, the shrinkage of a steamed cake may also be related to the proportion of ingredients used. If there is an excessive amount of protein in the cake, it will be too soft and prone to shrinkage. Conversely, if there is too little protein, the cake will be too dense and also prone to shrinkage. Therefore, when making a steamed cake, it is crucial to use the right proportion of ingredients.

In conclusion, the shrinkage of a steamed cake is caused by the physical and chemical changes that occur in the gluten and proteins of the flour at high temperatures, as well as the generation and release of carbon dioxide. Additionally, the proportion of ingredients used in the cake can also affect its shrinkage. To make a perfect steamed cake, it is important to have a good understanding of these principles and make appropriate adjustments to the various factors during the cooking process.