The skill of making a latte (1)

The popularity of coffee in China over the past few decades is as if you were born to know that it looks good. Pull flowers are no longer a new thing, and you must have seen it even if you haven't drunk it. The amazing thing is that many new things have already been upgraded in China, and there are no stories that have been explored and found to spread. for example, we don't need to know how coffee grows like a shrub and turn into a fruit like a cherry. We don't need to know how to turn this fruit into lovely coffee beans, maybe we don't even need to know how the coffee is made, just go to the supermarket and buy a cup of coffee. It may feel good to jump directly to Uygur, but that feeling is fleeting and there is no dimension of memory. I'm afraid that creatures living in the fifth dimension can't understand the joy of expecting a cup of cappuccino.

Of course, the high-style cafe still has manual flower drawing, watching the beautiful woman or handsome barista draw a wonderful pattern on the coffee with a shake of his hand, and then send you a reserved smile, gently take it over, and return it with a smile, with an instant glamour value of 10. Work efficiency × 100

So let's talk about what coffee pull is. Before that, let's ask: what is a Cappuccino cappuccino?

After 1525, monks of St. Franciscans wore brown robes and a pointed hat, and people called their clothes Cappuccino, and then they found that this coffee looked like this group of people, and gave this coffee the name, which is to add milk foam to espresso.

What's the difference between a cappuccino and a latte or Ole coffee?

In terms of composition, latte and Ole Coffee are Italian names and French names. Cappuccino, like these two, are milk bubbles steamed with coffee and steam, with slightly different air content, and some confuse these names. It doesn't matter. The technical details are described in more detail below.

What about direct coffee with cold milk? It's called American coffee because they're lazy.

But there are more and more cafes, but there are fewer and fewer places with cappuccinos. First, coffee is readily available on all kinds of packaged shelves because of the increasingly convenient and cheap way to get it, but Starbucks, McDonald's and all kinds of coffee shops are equipped with advanced coffee machines, which are machines that can make dense milk bubbles. They also sell cappuccinos, why can't they pull flowers?

Because the failure rate of Lahua is too high.

The reason for the failure is that they have not studied physical chemistry. Physical chemistry is a course called physical chemistry, not physics and chemistry.

In this article, I will briefly describe an important system in physical chemistry, foam: the application of foam in the coffee industry.

Ho-ho, do you feel magnificent?

Do you think you can just eat foodie?! Too young too naive!

Get to the topic: how to make a latte

First of all, what is the layer of flower floating on the surface of the coffee?

Maybe no one will think too much about this problem. But in the eyes of scientists, it is a mixture of two kinds of microfoam (microform), different colors, but you can enter me into you, so you can create patterns. So in order to get such a flower, you must make the two kinds of foam mix together.

Before mixing, we have to prepare these two bubbles, and then the two bubbles have to meet at the right time and in the right place, neither later nor earlier.

So first, we have to have foam from coffee, crema: coffee fat foam.

The picture above is a picture of coffee fat, the black part below is coffee, and the brown red part above is coffee fat, which is obtained from coffee powder which is washed by boiling hot water and finely ground under high pressure. it's because the foam mixture refracts the air. Chinese people generally do not drink espresso very much and think it is too bitter. In fact, it is important to taste espresso. Coffee fat is the soul of espresso flavor and the key to judging the quality of a cup of espresso and baristas.

The picture shows the microstructure of coffee fat foam. The presence of coffee fat is often seen as a sign of the quality of espresso, accounting for more than 10% of the volume of espresso. Coffee fat contains a lot of gas, about half of the total volume. The structure of coffee fat is observed under an optical microscope. It can be seen that it contains bubbles, fat particles (usually less than 10 microns) and some solid particles (fragments of the cell wall of coffee beans, etc.). Quoted from the right [Coffee pull: foam Waltz]

The amount of coffee fat foam is not only related to the coffee beans themselves, but also related to the tamping technology, that is, the action of putting coffee powder into a small container and then pressing it, the tighter the pressure, the easier it is to extract the coffee fat, but if it is too tight, the coffee may not flow out, so it is very skillful.