Hand brewing coffee Tetsu Kasuya invented four or six flushing method, the role of off-water flushing method?

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The 2016 World Brewers Cup champion, Tetsu Kasuya

The four or six rush method invented by him was used in the competition. Here is a brief introduction.

V60 ceramic filter cup, coffee powder 20g, rough grinding, water temperature 92 degrees, total water injection 300g

The total amount of water injection is divided into 40% and 60%, so it is called four or six punching method.

The first 40% of water injection determines the balance between sour and sweet, and the last 60% water injection determines the strength of coffee (strength).

The first 40% of the water, a total of 120g, will be injected twice.

If the first injection is less, it will be sweet, and if the first injection is more, it will be sour.

In the competition, he injected 50g for the first time and 70g for the second time.

The last 60% of the water, totaling 180 g, was injected in three times, each divided into 60 g.

The purpose of grading is to determine the intensity of coffee, too strong can reduce the number of times, for example, reduced to two times, 90g each time

After each injection, let the water flow completely to the next pot before the next injection.

It is observed from the film that each water injection takes about 5 seconds and a pause of 40 seconds.

So the last water injection is about 3 minutes from the first water injection.

I have no doubt that the cut-off method will increase the concentration of coffee.

What I have a question is why the first injection of water will be more sour and less sweet.

Although he is saying that the first two water injections will affect the balance of sour and sweet, it seems that the focus is on the first water injection.

It also reminds me of a passage I saw before.

"the taste of hand-brewed coffee was determined the first time it was injected with water."

I forgot where I saw it. I thought it was incredible at that time. It was bullshit. Laugh.

In order to learn and verify the four or six punch method, I went to medium baked beans with sour and sweet flavor descriptions, rather than shallow baked beans that emphasized sour taste.

The bean grinder is Baratza Forte BG, the hand flushing pot is the big moon rabbit seal, and the filter cup is V6002 ceramic filter cup.

The filter paper uses white filter paper, which claims to be in the same factory as KONO filter paper, and the paper grain is indeed the same.

After trying half a pound of beans, the experimental results are exactly what Kasuya said.

So the question is, what factors led to this result?

When the concentration is detected by ATAGO, it is found that the concentration of the first water injection is slightly lower, which leads to a slightly lower extraction rate.

Although the difference is very small, the concentration difference is only 0.0x%, even in the error of the instrument.

However, after many measurements, the concentration of the first water injection is slightly lower, resulting in a slightly lower extraction rate of about 1%.

This phenomenon is reproducible and should be credible.

I don't know if there are any acids in coffee beans that can be extracted most easily, while other substances are relatively difficult to extract.

I think it's possible for the following reasons.

The first water injection, the so-called steaming, is designed to drain the air from the coffee powder.

What are you doing with the air? Avoid air preventing coffee powder from coming into contact with water to facilitate subsequent extraction

So for the first time, if there is more water, the more water will flow into the kettle.

It means that the more water there is, the less the coffee is extracted, and then it flows into the next pot.

This is why the concentration and extraction rate are slightly lower.

If the acid is easily extracted,

In that case, during the pause after the first water injection, the coffee powder is steamed and discharged from the air, and the subsequent water injection will extract all the acid.

The total amount of water injection and time are fixed.

So the substance other than acid was not fully extracted during the first water injection.

Later, although the extraction was complete, the total amount of these substances was reduced because the amount of these substances was less than the one that flowed into the next pot during the first injection.

I feel that the amount of water injected for the first time will be sour, not because there is more acid, but because other substances are less, so it highlights the acid.

By the same token, when the amount of water injected for the first time is less, the amount of other substances extracted becomes more, and it will feel sweeter.

I have found another phenomenon, which may also support this claim.

I use the Mahlkonig Guatemala bean grinder, the same beans, visual the same thickness.

With the same amount of water injected for the first time, the amount of water flowing into the next pot will be more than that of Forte BG grinding.

(in the end, the total amount of water flowing into the next pot will be more than Forte BG grinds.)

I guess this is because Guatemala has less fine powder, so it keeps less water.

Since there is a lot of water flowing into the next pot, which is equivalent to more water injected for the first time, the coffee brewed out by the same method is also sour.

This may also explain why Guatemala can easily play the acid of shallow baked beans.

Some people think that the amount of steaming water must be controlled to the extent that it should not be dripped, and that it should not flow into the pot too much. It is reasonable to think about it.

It's just that you should act according to the bean system, depending on how you want to behave that bean.

In addition to hand flushing, espresso seems to have the same phenomenon.

Shallow baked beans are often very sour when making SOE, and some even feel a little unbearable.

If the pre-brew function of SLAYER is used and the pressure is increased very slowly, the extracted SOE will not be so sour and the sweetness will be doubled.

The extraction rate will also be increased by 1% to 2%.

Maybe it's the same thing.