What message can the oils of espresso convey? Can't the grease used for latte lahu be too thick?

As we all know, Crema is the iconic substance of espresso, and it is its appearance that distinguishes espresso from other coffees. However, the state of fat, like the taste of espresso itself, is constantly changing every day!

Sometimes thick, sometimes thin, sometimes silky and delicate, sometimes mouth-watering, sometimes rough and careless. In many cases, the concentrated oil with an unpleasant appearance is not very delicious, so there is a saying that "you can know whether this cup of concentrated oil is good or not through the oil." So is that really the case?

In fact, the state of oil is the same as the powder pit of hand-brewed coffee, the state of a cup of concentrated oil does not represent the taste of the concentrate itself. To investigate the reason, we might as well take a look at the structure of this layer of grease.

As we all know, grease is actually a less strict name, its real name is Crema (Klima), with the meaning of bubble. In fact, it is a bubble formed by filling the oil (the liquid oil of the coffee bean itself) with carbon dioxide. Most of the bubbles dissipate, and so does this layer of grease. Therefore, it will gradually disappear with the passage of time. When this layer of Crema dissipates, the reflector floating on the surface of the espresso liquid is the real oil (the liquid oil of the coffee bean itself).

Its production principle is very simple, that is, when we are extracting and concentrating, the pressure of the coffee machine as high as 9bar will squeeze the carbon dioxide released by the hot water directly into the oil, then seep out through the holes in the powder bowl and add it to the coffee, forming what we see as golden Crema.

What is high quality oil (Crema)? You know, in fact, this layer of grease has its advantages and disadvantages. In the public consensus, a high-quality oil is rich and delicate, the overall color is standard golden, has a high mobility, and shakes like a creamy sticky silky. Such a serving of oil will not only increase appetite, but also provide a good base for coffee flowers, so that baristas can better make flower patterns. So it is naturally called high-quality concentrated oil.

And if you want to get such a high-quality oil, then the choice of beans is very important. The content of carbon dioxide and oil in beans determines the thickness of concentrated oil. As a result, beans that are baked in medium and deep depth and are in the appreciation period (within two months from the beginning of baking) have become the preferred target. Medium-and deep-baked beans have more oil and carbon dioxide than light-baked beans because they are baked for a long time, and being in the taste period ensures that carbon dioxide is not lost because it has been stored for too long. Of course, if you do not dislike Luodou, then add a small amount of Luodou to this bean, you can get more rich fat!

The above is only the choice of beans, when we have selected beans, but also need to carry out reasonable grinding, stable and appropriate extraction, in order to obtain a high-quality concentrated oil. The more stable the beans are, the more stable the fat will be. As mentioned at the beginning, most of the time, the extracted oils may not be so satisfactory, and their stability will change due to the change of various factors. So Qianjie today will share what kind of problems these unsatisfactory oils are talking about.

Fat is too thick, rough caking, I believe people will extract this kind of oil from time to time: although very full, thick, but the speed of dissipation is super fast. Not only that, it is also very rough and illiquid, and the barista who used it to pull flowers said, "I can't push it! I can't push it at all!"

The reason for this kind of grease is very simple! Because the coffee beans are too fresh, not long after they have been roasted, the body is full of carbon dioxide. As the saying goes, they are young and energetic, so when the exuberant carbon dioxide is pressed out, the oil of coffee beans cannot be completely wrapped, so they will break through the oil and form the phenomenon of defoaming first and then caking. Too much carbon dioxide will hinder hot water extraction of flavor substances in coffee. Therefore, Qianjie suggests that it is best to put this fresh coffee bean on hold and raise him for a few days before extraction. This not only makes the oil more stable, but also makes it easier to extract delicious espresso.

Concentrated too thin, not even (medium and deep baked beans) from the subtitle, we can see that this situation is completely opposite to the above. The reason for this situation is mainly composed of two aspects. The first is what we mentioned above, the freshness of coffee beans.

When the coffee bean is too fresh, the carbon dioxide content will be high, but over time, it will slowly dissipate, and then the extraction will gradually stabilize. However, if time passes too much and exceeds the best taste period (two months after the start of baking), there will be little carbon dioxide left in the beans. Without carbon dioxide, the fat is naturally impossible to be thick. In this case, due to the absence of the hindrance of carbon dioxide, the extraction efficiency is greatly improved, and it is easy to produce extraction odor without paying attention. Therefore, Qianjie recommends buying beans as small as possible, multiple times. In this way, the taste period of coffee beans can be controlled within the time they can finish, or through sealed storage, the best taste period of coffee beans can be delayed.

Then there is the second situation: grinding problem! The Italian coffee machine is very demanding for the grinding of coffee powder. If you do not reach the required grinding thickness, not only can not extract oil, but also because the particles are too thick to form an effective barrier to water, so that the flow rate is too fast to extract the coffee you want. Therefore, the right particle size is very important, whether you are pursuing oil or taste. -END-

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