Why Does Latte Foam Disappear Quickly? What is the Foam on Top of Latte Coffee Called? How to Froth Milk for Coffee?

A freshly made latte has an incredibly delicate and smooth surface. However, if we leave it sitting for a while, we can observe the smooth and delicate surface gradually becoming rough and uneven. This phenomenon is called "foam dissipation," which is the process of milk foam continuously breaking down.

Milk foam is a foamy substance formed by injecting air into milk, so its quality is lighter than liquid. Under the influence of external forces such as frothing, shaking, and integrating, most of the foam will blend with the liquid, and at this point, the decomposition speed of these milk foam bubbles will be relatively slow. However, in a static state, the lighter foam will gradually rise to the top, while the heavier liquid will sink, leading to layering.

After layering occurs, due to pressure differences, these tiny bubbles will begin to slowly dissolve and combine into larger bubbles. When the air pressure inside large bubbles exceeds the strength of the proteins that contain the air, the bubbles will burst and break apart. Although the layer of milk foam floating on the latte surface will eventually dissipate, the decomposition speed can vary. For example, lattes made by FrontStreet Coffee can sit for ten minutes before showing obvious foam dissipation, while some other lattes may develop many obvious large bubbles shortly after being made, appearing rougher overall.

The reason for such a significant difference in foam dissipation speed between these two lattes is mainly their different stability levels. The higher the stability of the milk foam, the slower the foam dissipation; the lower the stability, the faster the dissipation. When you notice that a latte begins to lose its foam quickly shortly after being made, it indicates that the foam stability might not be high enough. Among the various factors that determine the quality of a latte, milk foam stability is one of them. Many factors can affect milk foam stability, so today FrontStreet Coffee will share with you what specific reasons influence milk foam stability.

1. Poor Milk Foam Preparation

A relatively common reason is inadequate milk foam preparation (this refers to the steps of frothing and texturing). As FrontStreet Coffee mentioned earlier, milk foam is created by injecting steam into milk, but simply injecting air is far from enough. We also need to texture these frothed large bubbles, cutting them into countless smaller, more stable bubbles. If the texturing step is not done properly, the resulting milk foam quality will be lower, with reduced stability, causing the latte foam to dissipate much more quickly.

There are mainly three reasons that lead to this situation. The first is insufficient texturing time, which occurs when the milk isn't cold enough or the target temperature isn't high enough, thus shortening the texturing time. Without adequate texturing time, the milk foam won't be as velvety, and the foam dissipation speed will naturally be faster.

The second situation is a challenge many beginners encounter: the milk doesn't form a vortex during the texturing process, pushed by the steam.

When milk doesn't form a vortex in the pitcher, the large bubbles generated initially cannot be drawn into the milk for cutting. Similar to the previous reason, the bubbles won't receive sufficient texturing, so the foam dissipation speed will naturally be faster.

The third situation, which even experienced baristas occasionally encounter, is accidentally exposing the steam wand to the surface during texturing, causing brief frothing. Finally, due to insufficient time, these large bubbles cannot be adequately textured, and their presence will accelerate the milk foam dissipation rate.

The above three points are common issues we encounter during the texturing process. If you can see many obvious bubbles in the pitcher after pouring latte art, it's best to pay attention to whether any of these three situations occurred during texturing. If so, it's best to improve them~

Additionally, after frothing milk foam, we tap the pitcher to eliminate large bubbles that weren't properly textured. While this can indeed be effective, when we tap the pitcher too many times, both the decomposition and layering speed of the foam will increase. Therefore, when tapping the pitcher, we should try to moderate the frequency and intensity.

2. Milk Temperature Too High

Next is the issue of milk temperature. As FrontStreet Coffee mentioned earlier, when the frothed milk temperature isn't high enough, the milk foam will have reduced stability due to insufficient texturing time. Additionally, when the milk temperature is too high during frothing, the stability of milk foam will also decrease.

When beginners learn to froth milk foam, the first thing to learn is controlling the milk temperature. The ideal temperature for frothed milk is between 55°C~65°C. The reason for controlling it within this temperature range is not only because this temperature activates the sweetness of milk but also because the milk foam can achieve considerable stability. When the milk temperature is below this range, as FrontStreet Coffee mentioned earlier, there may not be enough texturing time, leading to faster foam dissipation. When the milk temperature is too high, exceeding 70°C, some substances in the milk will be destroyed by the high temperature, significantly reducing foam stability. Not only will the foam dissipate faster, but the taste and sweetness of the coffee/milk will also decrease.

Therefore, when we need to create delicate latte art, it's best to control the milk temperature within the 55°C~65°C range. If not for latte art purposes, any milk temperature below 70°C is acceptable~

3. Material Issues

Besides operational issues, the materials used also determine the speed of milk foam dissipation. For example, when we use very fresh coffee beans, accelerated foam dissipation can occur. This is because fresh coffee beans contain a large amount of carbon dioxide. While this can help us extract richer crema, these oils are inherently unstable and will decompose quickly. When unstable oils combine with stable milk foam, the foam also becomes less stable, thus accelerating the dissipation speed.

This situation is the easiest to solve - simply let the coffee beans rest for about seven days, allowing them to degas and release carbon dioxide. This way, the extracted espresso crema will have higher stability and won't significantly affect the milk foam. The above are the reasons why milk foam dissipates quickly in a freshly made latte. Additionally, factors such as milk selection, foam thickness, and integration uniformity can also have an impact, but their influence is relatively minor, so FrontStreet Coffee won't elaborate on them here~

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Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473