What is the reason and solution to the decomposition and defoaming of the latte milk foam that has just been made?

To examine the quality of latte coffee, in addition to taste, fusion uniformity and liquid surface fineness, there is another standard, that is, the stability of milk bubbles.

The decomposition of the milk foam on the latte surface has already happened at the moment when the espresso is extracted and the foam is disposed of. The stability of latte foam is measured by the speed of decomposition and defoaming. Normally, the latte produced on the front street will be placed for about 10 minutes before there is an obvious defoaming phenomenon.

If the latte just made, at first the liquid level is extremely delicate, but after 2 minutes there are obvious "bumps", collapse, decomposition into large bubbles, this is an abnormal phenomenon, we need to find out the reason.

-the grease and milk foam themselves are very rough, although this reason should not be mentioned here, because it is impossible for rough grease or rough milk foam to merge into a delicate liquid surface, but it is still necessary to say that when both oil and milk foam are very rough, the milk foam layer on the surface of latte coffee will decompose easily. The thickness of latte surface foam the thickness of milk foam will also affect the speed of decomposition and defoaming. Generally speaking, the thicker the milk bubble is, the easier it is for the liquid surface to decompose a "pimple". In essence, the milk bubble is formed by protein wrapped in the air, so its mass will be lighter than that of the liquid, under the action of external forces such as dismissing, shaking, fusion and so on. can make most of the foam blend with the liquid, at this time the decomposition speed will be slower. In the static state, the heavy liquid will sink and the light foam will float, which is what we call powder delamination. The fine foam behind the powder layer will slowly dissolve and form large bubbles because of the pressure difference. From our point of view, the delicate surface becomes rough. When the pressure in the bubble is greater than the strength of the protein, the bubble will burst, and the burst bubble will appear a white pimple in the gold circle.

In addition to pay attention to control the thickness of the foam when passing the milk, you also need to pay attention to the cup of coffee. For example, the foam of the same thickness and volume will appear thinner on the wide cup and thicker on the narrow cup. Coffee beans too fresh coffee beans are rich in carbon dioxide, although you can get rich oils during extraction, but these oils themselves are unstable and easy to decompose. Therefore, after making a latte, the unstable oil is fused with milk foam, and it is easy to decompose and defoaming.

Qianjie generally recommends that espresso beans should be used for at least 7 days, so that the stability of the extracted espresso will be greatly improved. Shake the cylinder too often, sometimes at the end of the foam, there will be several obvious large bubbles. In this case, holding the milk jar in hand, gently tapping on the table can break the air bubble and make the surface of the foam delicate and smooth.

And sometimes bubbles are more or more stubborn, you need to knock a few more times to achieve a delicate effect. But the shock cylinder also has a side effect, that is, to speed up the separation of milk foam, the speed of foam decomposition is also accelerated. Therefore, Qianjie suggests that when it is found that there are many large bubbles, you can try to slowly move the milk tank down to form a whirlpool, so that the steam can break up the big bubbles on the surface and solve the big bubbles fundamentally. -uneven fusion of coffee and milk is not uniform, but also prone to the rapid decomposition of milk bubbles. Uneven fusion is generally shown as the color of the foam surface is different, careful observation, at first decompose faster is the dark color place, because these places contain more coffee oil, coffee oil will dissolve faster than milk foam. Therefore, only when the fusion is uniform, the liquid surface is not easy to defoaming quickly.