Some things about Coffee extraction Summary of incomplete extraction of roasted coffee beans

first

Coffee won't all melt when thrown into the water. The maximum extraction rate of roasted coffee beans is 30% (substances that can be dissolved in water divided by the total weight of coffee). This looks like crap.

Meaning:

1. Whether it's French pressure, Philharmonic pressure, all kinds of pressure, or espresso. The range of the best extraction rate is 18% Mui 21%. Insufficient extraction (less than 18%) means that the flavor of coffee is not fully dissolved in water, and excessive extraction (more than 21%) means that the miscellaneous flavor of coffee is integrated into the water.

Baristas rack their brains to make the perfect cup of coffee, all based on this.

two。 It is surprising that all our instant coffee can be dissolved in water. It shows that instant coffee has been extracted and reduced to powder in some chemical way. Exactly how to do it is outside the scope of discussion here.

(to put it simply. Instant solution is a powder formed by spraying the prepared coffee liquid in high temperature air.

Second

Coffee is actually part of the fruit. Since it is necessary to bake coffee, in a sense (not absolutely), coffee has changed from fruit to dried fruit.

Meaning:

1. The plum we sometimes drink, the citrus is actually its predecessor, combined with the flavor of the fruit in the local environment; the almond and walnut flavor we drink is partially carbonized after baking. We drink cocoa (a bitter taste) and syrup (a combination of bitterness and sweetness) is a deeply baked, carbonized taste.

two。 For one thing, we understand why coffee is popular for roasting. Like steak, the outside is charred and tender inside, there is cocoa and dried fruit flavor brought by carbonization on the outside, and the inside still retains the sweet and sour fruit. This brings a richer taste.

3. Many people tirelessly pursue a certain flavor of the theory of taste. But it ignores the rules of flavor wheel arrangement.

From bottom to top, it is actually a gradual distribution of carbonization degree.

The bottom is smoked and scorched, and the top is floral.

4. Most importantly, coffee is not just bitter. At least that's not the case with good coffee.

Third

The grinder is the process of turning coffee beans into powder, which is another piece of nonsense, but

1. The finer the grinding, the more coffee is exposed to the air surface and the faster the volatilization time is. Espresso requires the finest powder, once ground into powder, most of the flavor will be lost in 2 minutes.

two。 Why wouldn't I recommend a hand grinder to make espresso. Because it takes far more than 2 minutes to shake 20g powder by hand.

3. If the powder particles are inconsistent, the same hot water passes through small particles, too much extraction (more surface of exposed water), and not enough extraction after large particles (less surface of exposed water)

4. The filter bowl of the pressure kettle is very thick, so it is required to grind large particles. Therefore, the requirement of the grinder is high, because if the size is different, there will not only be the third problem, small particles will wear a filter, such as coffee turbidity.

Fourth

No matter what kind of drink, the taste that is suitable for the public is often balanced. In coffee, it mainly reflects the ups and downs.

Meaning.

1. Bitterness and bitterness can be felt by normal people. If you calm down, you can feel these three smells.

two。 The sour taste is more sensitive on both sides of the tongue coating, the sweet taste is at the tip of the tongue, and the bitter taste is at the root of the tongue. Due to the shadow of bad coffee in the past. Many friends try black coffee for the first time, just want to taste it, as soon as they drink it sour, it is easy to give up.

Coffee actually requires a big sip to quickly cover the taste buds.

3. Normal people with unbalanced taste can judge coffee with a little guidance (this has been confirmed many times in my personal experience).

4. Some people say that if you drink 1000 cups of coffee, you will know how to taste it. In fact, a good cup of coffee with the right guidance is enough.

For this picture, a lot of assumptions and calculations can be made. In fact, it is not new knowledge, we know how to adjust the grinder, the amount of powder to control the balance, but also know the relationship between coffee freshness and extraction.

But the difference is that we hope to integrate a new framework between these existing knowledge and the North American knowledge system. It's not really new knowledge, just sort it out and share it with you. Because it has a certain guiding significance for the Philharmonic pressure, Italian style and the hand punching that I mentioned earlier.

A key point mentioned above is the extraction rate. In real life, I find that even many baristas confuse concentration with extraction rate.

First of all, the concentration represents the amount of soluble matter (TDS) in your cup of coffee, so:

TDS%= TDS/Coffee Weight (CW)

It is very simple and clear that the concentration represents the total weight of a cup of coffee soluble matter. So the higher the concentration, the stronger your coffee.

Generally speaking, the reason why we drink espresso is very strong, because its concentration is about 8% Mur11%, while filtered coffee is very light, because its concentration is about 1.15-1.4%.

(depending on whether it is an American SCAA or an European SCAE standard, which will be discussed later.)

Concentration, what is the percentage of soluble matter in coffee?

What about the extraction rate?

Do you remember what I said above? Coffee beans cannot be 100% integrated into water, and soluble matter in coffee accounts for a percentage of coffee powder that was previously extracted.

Besides, to put it more popularly, how much substance in coffee has been incorporated into coffee? Therefore, the extraction rate is that there is a very important concept of TDS/DOSE (gram weight of powder). The reasonable extraction rate will be between 18% and 22%. If we extract too much, we will drink bitterly and have a mixed smell.

If it is less than 18%, the coffee we often drink will be sour. It must be mentioned that whether it is espresso or filtered coffee, the extraction rate is in this category.

Extraction rate, how much of the coffee has been extracted?

If you are exposed to these for the first time, you will feel a little dizzy. Let's start with a topic hypothesis:

The amount of powder is 20g, hand-washed with 350ml (g) water, and about 300g of hand-brewed coffee is obtained. We detected it with a concentration meter, and we got a concentration of 1.2%.

We know it is.

TDS% = TDS / Coffee Weight

You already know it's 1.2%.

Next, we can know how many grams of soluble matter are in it, that is, 300g of coffee with a concentration of 1.2%.

Then the soluble substances are:

300 million 1.2% 3.6g

Then we know that this is obtained from 20g of powder, so

The extraction rate is

TDS/Dose = 3.6max 20 = 18%

Therefore, we also know the extraction rate. 18%. This should be a good index of extraction rate.

As long as the coffee is fresh and evenly extracted, it should have a good taste.

(of course, in the end, you have to drink and judge the taste.)

What's more, we know the relationship between concentration and extraction rate.

(here, you can understand why the concentration of European boutique coffee is 1.2% as the reasonable minimum for hand brewing, because it is exactly 18%.)

Next, let's go back to this picture to make their relationship clearer.

Let's first look at the horizontal axis of the picture, which is, in fact, what I call the extraction rate.

As mentioned earlier, the best extraction rate of coffee is 18-22%.

If you look at the vertical axis, it is the concentration, if it is hand-brewed coffee, and it is the European boutique coffee standard, it is 1.2-1.4%.

Then it will be clear when we see this picture, because that gray area belongs to the scope of making filtered coffee more reasonably. (friends of baristas who make espresso, according to this picture, you should know where the area of espresso is)

These are compulsory courses to learn in the early stage, to adjust the amount of powder, grinding degree, or extraction time according to the taste.

Of course, in the hand-brewed coffee, it is the velocity of the water, the temperature of the water and so on.

If you change the amount of powder or water, yours

Concentration (TDS/Coffee weight, which varies depending on the amount of coffee powder)

Extraction rate (the amount of TDS/DOSE powder has changed, but so has the dissolved matter)

How can you tell how much this factor has changed is a variable?

This can be based on experience, but what if the store is open?

Here's Intelligentsia, and Michael, their operating system.

If anyone who has studied math knows that if you divide the vertical axis by the horizontal axis, you will get a diagonal line.

So what will it be in this picture?

We know that the vertical axis is the concentration ratio.

That is, the horizontal axis of TDS/Coffee weight is the extraction rate.

That is, TDS/Dose division:

(TDS/Coffee Weight) / (TDS/ Dose)

We ask TDS out and we get Dose / Coffee Weight.

So this line represents the ratio of coffee powder to coffee gram weight.

Also known as Coffee Brewing Ration (in Italian concentration, that is, EBF)

Going back to the example just now, the coffee powder weighs 20g and the coffee weighs 300g.

So the angle of this slash is that for every 15g shift, the concentration will increase by 1g in proportion, that is, 1:15.

And this diagonal line will run through the gray area just now, that is, the best reasonable extraction range.

What is the meaning of it?

If we fix the water temperature 94 °, the weight of 350g coffee powder is 20g, in fact, we only need to adjust one parameter, the thickness of the grinding degree, we can make the concentration point of the extraction slide along this oblique line and enter the category we need.

If, we get coffee concentration of only 1.1%.

We can know that the TDS is 300g * 1.1%, that is, the extraction rate of 3.3 g is 3.3 + 20 = 16%.

It is obvious that the concentration is low and the extraction is insufficient. The taste you drink should be sour.

This means that you only need to fine-tune the grinding degree to improve the extraction efficiency per unit time. Conversely, if you get a concentration of 1.5%.

We can know that the TDS is 300g * 1.5%.

That is, the extraction rate of 4.5g is 4.5pm 20 = 22%.

Here, you should drink coffee with obvious flavor (a lot of experiments have been done, basically), because the extraction is too much.

Then all you have to do is adjust one variable to thicken the degree of grinding.

See here, we can see its significance, we do not through the past, ask everyone to pay attention to various variables, but the powder and beverage weight ratio fixed, then you can just adjust the grinding degree to find the best flavor point.

Of course, this is not an omnipotent formula, and it has its limitations:

1. Fixing the gram weight of powder and drink means that you can adjust the grinding degree in only two directions.

two。 Whether by hand or consciously, it is assumed that the frame is extracted uniformly.

If the extraction is uneven, the concentration value is of no reference significance.

But in any case, it is of great significance to the operation of a store.

Because an experienced baker and barista only needs to tell the operating unit how many grams of powder and how many coffee drinks can be debugged.

The rest is left to the store to adjust the degree of grinding.

Even, if it is espresso, tell how many grams of espresso, about how many seconds of extraction time, coffee quality control is quite accurate.

Of course, many people will say, what if I don't have a densitometer?

So it looks like a mathematical formula, and we have to go back to the origin. We should at least judge from the taste what kind of taste is excessive extraction and which taste is insufficient extraction.

At the very least, baristas themselves should be based on their own senses, right?

"it's a matter of thinking for people who make espresso. In theory, if you find that the flow rate slows down during extraction, it will be excessive extraction. You can either thicken the grinding degree or reduce the amount of powder. But if the extraction rate is TDS/DOSE, if you reduce the denominator, isn't the extraction rate even more excessive? "

In the case of espresso, the degree of grinding is very sensitive to espresso, and the larger the grinder, the larger the cutter head, the more obvious. Therefore, the grinding scale of espresso is stepless adjustment is also the reason.

Back to the table, suppose you adjust fine and the gouache ratio is the same, then the extraction point will slide to the upper right, which means that you will taste in a bitter direction and go in a higher concentration direction.

(here I would like to emphasize that there is no difference between bitter and sour, only whether it is balanced or not.)

Source:

The blog of coffee man Lu Xiansen