Introduction to Coffee extraction: what are the detailed requirements for making espresso?

Espresso, the "soul" of the Italian coffee system, can be extracted in just twenty or thirty seconds, but before pressing the brewing switch to officially start extraction, once some small details of the operation are not in place, it may cause your coffee to taste bad.

Today, let the front street give you an inventory, making espresso you may not have noticed 7 small details.

1. Before falling powder, the powder bowl is not dried.

After the extraction is complete, discard the powder cake, rinse the powder bowl with water to remove the residual coffee stains (/grounds), and dry the powder bowl before extracting the next handful. This should be a default action for all baristas.

However, some friends are more anxious, do not dry the water stains in the powder bowl to pick up coffee powder, then contact the powder bowl powder first, will be wet in advance and stick into a ball, and then spread powder pressure powder on these "powder ball" impact is very small. Therefore, it is not difficult to understand why the concentrate flow rate fluctuates and the final Espresso taste is very unstable when extracting under such conditions.

2. The ground coffee powder is seriously agglomerated.

Because the powder used in espresso coffee is "as fine as flour," it is easy for coffee powder to clump during grinding. At the same time, some too dry weather will also cause the original no lumps, become very obvious.

Although nothing can be seen after filling, this lump powder has a tighter structure, which makes it difficult for hot water to penetrate, and finds a way to escape with less resistance. Finally, a channel is produced, and when it is serious, it is accompanied by the phenomenon of liquid column injection, which affects the coffee flavor. When you find that your ground coffee powder has very obvious lumps, you may wish to use a cloth powder or fine needles to gently break up these lumps.

3. If there is no cloth powder, directly fill the powder cake

Simply put, powder distribution is to evenly distribute the coffee powder layer in the powder bowl, so that the hot water "fairly" penetrates each coffee particle, so that their extraction state is as consistent as possible.

However, some friends receive (fall) powder, there is no "leveling" powder layer on the powder hammer to fill pressure, from the surface of the powder cake will have a little bit of inconspicuous depression. At the time of extraction, hot water at 9bar concentrates on this "pit," leading to perforation and associated ejection of the liquid column. In addition, if there is residual water on the powder hammer, it will also take away some coffee powder and make the powder table uneven. Therefore, Qianjie recommends that the fluffy coffee powder tends to be flat as much as possible after receiving the powder, and then fill it, or use a powder dispenser (/powder dispenser) to assist in powder distribution.

4. The filling force of the powder cake is uneven.

In addition to uneven powder distribution, improper compaction of the cake can also affect the flavor of the final concentrate. Some coffee friends just contact Italian concentrated production, filling action is not skilled, will repeatedly back and forth pressure powder. Although the final powder layer looks very flat, the actual density distribution of coffee particles in the interior has been "unrecognizable," and extraction is more likely to produce channel effects.

Therefore, when pressing powder with powder hammer, try to do it in one go. If it is really difficult to complete, Qianjie suggests to review the filling action again.

5. Accidental bumping when buckling the handle

There have been encounters in the front street, new colleagues just contact the store coffee machine is not familiar with it, will be in front of the brewing head a little groping, bump, can find the correct angle button handle. This may greatly increase the probability that the cake, which is originally tightly adhered and compacted with the powder bowl, will separate and "break up" and eventually lead to the "perforation" channel effect. This situation is not only very common in home homemade, but also common in some novice baristas with large movements. (Ps: Front Street will give such new colleagues some time to adapt before participating in daily production.)

6, the brewing head did not put a little water

Every time you remove the handle to throw the powder cake, press the brew switch to drain the water, which may be a subconscious action of the bar barista. This is because after extraction, there will inevitably be some coffee grounds and coffee stains left on the water separation network. If you don't wash it off in time, it will have been dried and stuck on it by the time of the next handful. Finally, it will be extracted together, so the concentrated taste can be imagined.

There is also a case that the interval between this extraction and the last time is long, the temperature of the powder water network on the brewing head is too high, and there is a probability that the surface coffee powder will be burnt when the handle is directly buckled, which may lead to burnt bitterness in the concentration.

Therefore, in order to avoid the negative taste of coffee caused by the above situation, Qianjie recommends that everyone form the habit of putting some water before extraction.

7. Press the brewing switch at intervals after buckling the handle.

Some basin friends press the powder button on the handle, found that they are not ready to zero the electronic scale, and then busy for a while, and then wait until the extraction button is activated, the extracted coffee is likely to have a bitter taste. (Qianjie often waits ten seconds for focus when taking photos, and the final concentration has a bit of a burnt smell.)

Because the temperature of the brewing head is very high, after the handle is buckled, if the extraction is not started in time, the powder cake will be baked at high temperature and will have a burnt smell. Therefore, remember to do all the preparation work (electronic scale, shot cup, etc.) before buckling the handle, and immediately open the extraction once fastened, so as not to let the coffee over-extract waste.

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Front Street Cafe

No.10 Baoanqian Street, Yandun Road, Dongshankou, Yuexiu District, Guangzhou City, Guangdong Province