In the production of drip coffee, controlling the extraction of coffee is the most important and at the same time the most difficult. There are many factors associated with extraction, including grinding degree, powder-to-water ratio, water temperature, etc. Only proper extraction can lead to a good cup of coffee.
The three-stage theory of drip filtering can help you understand the extraction process, and using it can help you make a good cup of coffee. I interviewed Patrik Stridsberg, co-founder of 3TEMP, and Will Corby, a coffee professional in London, from whom I learned a lot about extraction. Read on and see what I've learned.
1. Steaming
Steaming (bloom) is the first step in hand brewing coffee. Pour a small amount of water into the ground coffee, just soak the ground coffee, and wait about 30 seconds. The reason for this is the exhaustion of gases (mainly carbon dioxide) from the coffee powder.
During the roasting process, a large amount of carbon dioxide is produced in the coffee beans. After roasting, the carbon dioxide in the coffee beans is slowly released. After contact with hot water, carbon dioxide is quickly released, resulting in the flower-like exhaust phenomenon seen during steaming (so the English steaming is called bloom (flowering)).
There are two main effects of steaming. First of all, carbon dioxide can give coffee a bad sour taste. The elimination of carbon dioxide is beneficial in ensuring the taste of coffee. Secondly, when the coffee is vented, the force of the gas will also push the water away, avoiding the extraction at this stage, resulting in the problem of uneven extraction.
2. Extraction
In the next stage, you can start to control the taste of the coffee. Different flavors are extracted at different stages: first sour, then sweet, and finally bitter. (It's worth noting that not all acids are fruity, ideally acids.) For example, caffeylquinic acid produces an astringent, bitter taste. When we talk about acids in this article, we refer to chemicals that produce an acidic taste. ）
Since the chemicals extracted at different stages are different, you can control the taste of the coffee by controlling the extraction process. The best way is to control the water temperature and the brew time.
In general, the ideal boiling water temperature is 91°C~96°C (196°F~205°F). The temperature of the brewed water can be determined according to factors such as the roasting, flavor, freshness and grinding degree of the coffee beans.
Patrik told me that another important issue to consider at this stage is "pulsing." Refers to the number of times the water flow is injected in sections during water injection. In the process of hand brewing coffee, in order to ensure the consistency of each brew, many people recommend reducing the number of water injections in segments, which reduces the variables that the barista has to control.
Patrik, however, thinks "pulsing" is important. In fact, Patrik programmed it as a controllable variable into the brewing program of the Hipster coffee machine, because he believed that it would improve the consistency and efficiency of the extraction. Patrik explains that fewer, larger streams of water shorten the extraction time, while more frequent, smaller streams of water increase the extraction time and keep the ground coffee noodles in balance. The optimal number of segments depends on the characteristics of the coffee beans and their abrasion.
3. End phase
Patrik told me that the "end phase" refers to the last 40% of the brewing process, and you need to control it carefully. The last chemicals extracted are those that cause bitterness and other unpleasant tastes. If you accidentally over-extract, then this cup of coffee is tragic.
Patrik recommends paying attention to the time of brewing and the temperature of the water. If the water temperature is low, there will be less extraction, and if the water temperature is high, the extraction will be more. So pay attention to the water temperature and time, help to get a cup of coffee with a balanced sweet and sour.
If you use a hand punch, you don't have to worry about this problem because the water cools down naturally during the injection process.
However, if you are using a drip coffee machine, you need to consider the temperature of the brew when programming. Patrik explains that the default settings for the Hipster coffee machine are: the steaming temperature is 97°C (206.5°F), the extraction temperature is 94°C (201°F), and the temperature at the end stage is 89°C (192°F), which is 5°C lower than the extraction stage.
Although he suggested adjusting the parameter settings to different beans, he told me that this cooling mode is best for extracting good flavors such as sweet and fruity flavors.
Whether you're brewing at home or preparing for guests at a café, it's important to understand all aspects of the brewing process. Changes in water temperature are one of several key factors that need to be controlled.
Understanding the three stages of drip coffee making can help us control the temperature and make the delicious coffee we want.
