Milk powder and coffee, why they don't dissolve

The reason why milk powder and coffee do not dissolve

Milk powder and coffee are common foods in our daily life, but sometimes we find that after adding them to hot water and stirring, they still cannot be completely dissolved. This arouses people's curiosity. What exactly causes this situation? This article will analyze the reasons why milk powder and coffee cannot be dissolved from a chemical perspective.

Background knowledge: Dissolution of substances

Before we start the analysis, let's first understand the dissolution process of substances. When a solid substance (such as milk powder or coffee) is added to a liquid (such as water), if it can interact with the liquid molecules and form a stable and uniform mixture, it is called soluble in the liquid. Otherwise, it is called insoluble in the liquid.

Reasons why milk powder does not dissolve

First, let's take a look at why sometimes milk powder cannot be completely dissolved after adding hot water. In fact, this is mainly due to the following two reasons:

1. Denaturation of protein: Milk powder contains a lot of protein. When hot water is added, the high temperature will cause the protein to denature. This denaturation will lead to enhanced interactions between protein molecules, thus forming clumps.
2. Lack of emulsifiers: Milk powder usually contains a certain proportion of emulsifiers, which can help fat and water molecules mix better. However, in some cases, the milk powder may not have enough emulsifiers or the emulsifiers have aged and become ineffective.

The reason why coffee does not dissolve

Next, let's take a look at why coffee may not dissolve. Similar to milk powder, coffee also has the following two main reasons:

1. Loss of volatile substances: After roasting, coffee beans produce many volatile substances (such as aroma), which are easily lost over time. If you use coffee powder that has been stored for a long time or is not sealed well, most of the volatile substances may have been lost, making the coffee insoluble.
2. The presence of oils: Coffee contains a certain proportion of oils, which are difficult to interact with water molecules and form a uniform mixture. Therefore, during the brewing process, some oils may float on the water surface without being dissolved.

in conclusion

In summary, the insolubility of milk powder and coffee is mainly due to the characteristics of their ingredients and external conditions. For milk powder, protein denaturation and lack of emulsifiers at high temperatures are the main reasons; while for coffee, the loss of volatile substances and the presence of oils lead to the insolubility. When using these foods in daily life, we can adjust the usage method according to the specific situation or choose more suitable products to avoid the problem of insolubility.