Why do you use different temperatures for hand-brewed coffee? Introduction to the technical characteristics of variable temperature cooking method

A few days ago, the world-class coffee brewing competition ended successfully, and Qianjie found that many contestants used variable temperature brewing methods on the field. At this time, some people may wonder, obviously the same coffee bean with the same method, only change the water temperature, coffee flavor will have such a change? Today, Qianjie will take you to have a little fun and change the temperature to cook.

Brewing plan: 15g coffee powder, powder-water ratio: 1:15, three-stage water injection, each section is 30ml, 120ml, 90ml respectively. First of all, the first pot is a conventional constant temperature three-stage type, which is used as a basic comparison. The next two pots of temperature adjustment

The temperature of the first pot changed, and Qianjie wanted to highlight the fruit tone of the coffee, so it increased the water temperature by 2 degrees to maintain its extraction rate in the front and middle section. And in the last stage, the lower water temperature is used to weaken its extraction rate, avoid the extraction of bad substances, and form a step variable temperature extraction.

As the temperature of the second pot changes, Qianjie hopes to get a soft cup of coffee, so it has to lower the water temperature in the stewing stage and reduce the acidity released during stewing, while the second stage is used as the key extraction part. So use high temperature in the front street during the second stage of cooking, and then return to low temperature at the end to match soaking, just like the variable temperature ① to prevent the extraction of bad substances.

The high temperature is higher than the conventional extraction, we increase 2 degrees Celsius in the case of conventional cooking using 92 degrees Celsius, and the low temperature is 85 degrees Celsius (tested in the front street, shallow and medium-roasted coffee beans in the use of water temperature below 85 degrees Celsius will cause insufficient extraction).

Start the experiment.

Preparation for brewing: several hand pots, several thermometers (omitted with thermostat), coffee beans, V60 filter cups, and the less important coffee meter (TDS) are used to verify the extraction rate of variable temperature brewing.

Beans are used for cooking: beans use light-baked Panamanian Alida's tin card because it has rich floral and fruit notes, which is helpful to the flavor identification of this experiment. Grinding is medium and fine grinding, that is, the pass rate of China's No. 20 screen is 80%. (the front street uses the store's bean grinder EK43s with a grinding scale of 10)

The experiment begins.

The purpose of this experiment is to compare what kind of coffee a bean brews at different temperatures, so the front street does not show too much detail about the brewing process. )

Measurement result

After brewing, the concentration of each group of coffee was measured in the front street in order to determine whether the three groups of coffee were extracted reasonably, but the measurement results of the three groups were not insufficient, and the gap was not large. (concentration TDS (%) × Coffee liquid weight (g) / Coffee Powder weight (g) = extraction rate (%)) Let's compare it with the flavor test.

Flavor taste

First of all, let's talk about the flavor of conventional constant temperature cooking: elegant white flower aroma, bright citrus acid, as well as honey texture and tea finish, balanced and smooth!

The variable temperature ① with high temperature in the front and cooling in the back has a richer tropical fruit flavor than the constant temperature group, and the flower smell is slightly weaker. At medium and low temperature, the tropical fruit has a honey texture and evolves into a fuller fruit juice.

Steamed and low temperature at the end of the variable temperature ② reduces the acidity, the flower fragrance is slightly higher than the conventional constant temperature, the honey peach is slightly sweet, soft citrus, the finish rhyme is very clean tea, the whole is like an elegant cup of English flower and fruit tea.

There should be clever friends who have found that the concentration of the first pot is lower than that of the second pot, although it is made at a constant temperature. What is the principle of this?

First of all, as the reference of constant temperature cooking, it actually has a variable temperature process, and the temperature we mentioned above is the measured temperature at the beginning of cooking. With the passage of time, the hot water in the pot gradually lost its temperature. taking the water temperature of 92 degrees Celsius as an example, the water temperature of 92 degrees Celsius during steaming to the instant of water injection in the third stage, it has dropped to about 89 degrees Celsius (1 minute 20 seconds).

The second is that the water temperature is very important for the extraction, and the water temperature of each stage will affect the corresponding extraction. For example, it reduces the water temperature in the stewing stage, which significantly reduces the acidity of the whole cup of coffee, while the decrease in the temperature at the end directly slows down the extraction speed and limits the release of some macromolecular substances, such as bitter substances.

By understanding this framework, people can better control the brewing and get the delicious cup of coffee they want.

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Front Street Cafe

No. 10 Baoqian street, Yandun road, Dongshankou, Yuexiu district, Guangzhou, Guangdong province