How good or how little coffee grease is? What is the reason why there is no fat in concentration? What does Crema mean?

Crema, this golden foam not only serves as a unique symbol of pressurized coffee, but sometimes it can also help us find out where the problem lies.

Many friends often encounter the situation that there is no oil in the extracted espresso. It is well known that the main components of Crema are carbon dioxide and the lipids of coffee beans. If the extraction concentrate uses shallow roasted coffee beans that are not so rich in carbon dioxide, then it is normal that the oil is not rich enough. If we use deep-roasted coffee beans with a lot of carbon dioxide, but there is no oil, then Qianjie believes that it is likely to be caused by the following two reasons!

First, the grinding is too rough! If there is no oil in the concentrated extract, and the coffee liquid flows very fast during the extraction process, then in this case we can basically conclude that it is caused by excessive grinding. Due to the coarse particle size of coffee powder, the gap between the powder and the powder increases, even if the filling is compacted, it can still let the hot water pass easily.

Because of the low resistance and the fast penetration rate of the coffee liquid, the coffee machine naturally will not exert too much pressure for extraction. Stress is the main factor contributing to the production of Crema, when there is a lack of pressure, coffee naturally will not have a lot of oil. This situation is the most common, because many friends will always apply the same degree of grinding during extraction and concentration, using it from beginning to end, without changing the degree of grinding. The state of coffee beans is constantly changing every moment of the day, and these changes will affect the flow rate during extraction and concentration. For example, it took 32 seconds to extract 40ml espresso with 20g powder the day before, but only 20 seconds to extract 40ml coffee liquid with the same amount of powder the next day.

Then many friends will be more clever, adding powder when the flow rate is fast, and reducing powder when the flow rate is slow. This is a good choice, but the capacity of the powder bowl is limited after all, when the state of coffee beans changes greatly, even if you add powder, it is difficult to increase the resistance of pressed powder, and the coffee machine will not provide pressure without resistance. in the end, it won't be able to form rich oil. So, in a situation like this, we need to fine-tune grinding! In the past, the morning adjustment of Qianjie Street was first adjusted according to the formula. The formula was to use 20g powder and take 28032 seconds to extract 40ml coffee liquid. If the time was below this range, grinding adjustment would be carried out. For example, if it takes only 20 seconds for 20g powder to extract 40ml coffee liquid, then you need to fine-tune the grinding by 2x 3 squares, and then fine-tune it by taste (the fine-tuning object can be either liquid weight or powder quantity).

Second, coffee beans are not fresh enough. As mentioned in the front street, carbon dioxide is the main component of oil. When coffee beans are not rich in carbon dioxide, it is naturally difficult to form rich oils. So generally speaking, the oil extracted from shallow roasted coffee beans can not compare with deep roasted coffee beans. In addition, the freshness of coffee beans will also affect the richness of oil. The fresher the coffee beans are, the more carbon dioxide is stored in the body and the more fat is extracted. As the coffee beans stay longer, the amount of carbon dioxide in the body decreases, and the extracted oil becomes thinner compared to the fresh stage.

In general, coffee beans can extract rich oil within two months of baking (as long as the beans are deeply baked and stored properly). After two months, the thickness of the extracted oil will decline at a rate visible to the naked eye. So we can know that the freshness of coffee beans not only affects the flavor of coffee, but also affects the richness of oil.

Last

Finally, Qianjie would like to mention that the oil of espresso is mainly a group of bubbles filled with carbon dioxide, although it is misnamed "grease", but it is not essentially the kind of oil we know in our daily life. At the same time, the more oil, the better. Under proper extraction, the richness of oil is mainly determined by the variety of coffee beans and the carbon dioxide content of coffee beans. These two factors are not the key factors to determine the quality of coffee, so oil should not be used as the standard to measure the quality of espresso.

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