Nav: Home > Coffee >

Solutions to Latte Milk Foam Decomposition Problems and Illustrated Guide to Perfect Latte Milk Frothing

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, Have you ever ordered a takeaway latte and found yourself opening the lid to examine the milk foam? At first, I would habitually open the lid to admire the latte art, but later, I began observing the fineness and stability of the milk foam itself. Sometimes, the foam in the cup isn't puffed up but sunken in; other times, the

Observing Latte Milk Foam

Have you ever tried ordering a takeaway latte and opening the lid to observe the milk foam? Initially, I used to habitually open the lid to look at the latte art, but later I started observing the fineness and stability of the milk foam.

Sometimes, the foam in the cup isn't puffed up but concave; sometimes, the foam appears very hard, and no matter how you shake it, the foam remains motionless. Sometimes, when you first open the lid, the foam is incredibly fine, but within 2 minutes, you can visibly see the foam decomposing. In a quiet environment, you might even hear a "xi~xi~" sound like detergent foam popping. Of course, I haven't been that unlucky—most of the time, the latte I receive is still fine and silky, and after drinking, that layer of fine foam and latte art remains intact at the bottom of the cup.

Analysis of Milk Foam Collapse

In response to these various latte milk foam phenomena, FrontStreet Coffee feels it's necessary to analyze the causes of these situations one by one. First is the concave milk foam, which means the foam has collapsed. This is mainly caused by over-thick milk foam and relatively thin crema. FrontStreet Coffee has mentioned in the previous article about latte art with moka pots that coffee can be blended and create patterns even without crema. However, careful friends might notice that milk foam blended without crema appears lighter in color—coffee crema acts as a stabilizer for the foam. Although it can be fine at first, without crema, it easily decomposes into visible bubbles.

When the bubbles can no longer support the weight, they burst. Then when the foam layer is relatively thick, it will collapse, which is what we see as the surface of a cup of coffee concaving downward.

Hard Foam and Severe Layering Issues

Next is the problem of hard foam and severe layering. Basically, all latte coffee eventually reaches this outcome, but a well-blended latte can slow down this layering state. Over-thick milk foam also causes severe layering in the resulting latte.

You can try this: when you just make a latte, take a sip immediately, and the surface foam will flow along with it. But if you wait about 5 minutes before taking the first sip, you'll only make a small hole in the surface foam and drink the latte coffee beneath the foam. If the foam is too thick or improperly blended, this effect can be achieved in just 2 minutes.

Coffee Surface Decomposition

The main cause is unstable (rough) coffee crema. Crema has the effect of stabilizing milk foam, and when the crema is unstable, it can easily cause the originally stable foam layer to decompose, resulting in a lumpy feeling or dense bubbles on the latte surface.

Causes of Unstable Crema

There are two main possibilities for unstable crema. The first is that the coffee beans are too fresh—that is, the time between roasting and use is less than 7 days. At this time, the carbon dioxide in the coffee beans is still quite abundant, which will make the crema unstable during extraction, easily decomposing into large bubbles. The second is improper extraction.

Another situation is when the coffee crema is fine, the milk foam is fine, and after making the latte, the surface is also very smooth and delicate. But after a short while, large bubbles form all around the rim near the coffee cup wall, while the center remains fine. This is mainly caused by water stains on the coffee cup. If there's water's influence, the foam near the cup edge will become unstable and decompose, while the center remains stable.