The knowledge of coffee extraction in boutique coffee.

Let's start with this picture. I have posted in my photo album, a teacher of Korean coffee champion, a Q grader, a contact person in charge of world events, a world champion, together with me, look very different.

Let's start with this picture. I have posted in my photo album, a teacher of Korean coffee champion, a Q grader, a contact person in charge of world events, a world champion, together with me, look very different. In fact, Michael Philips takes the trouble to explain to others the relationship between extraction rate and regulation. In this photo, I don't seem to care. I pose. In fact, during the past few days with him, I don't want to emphasize how approachable he is, nor do I want to possess the suspicion of being close to his thigh, but he gives me a few knowledge points, which is the same as me in the coffee capital, and I am quite impressed by the collision I have learned in Melbourne.

At the end of the event, apart from taking a quick look at the wonderful videos of several contestants in Brista, what made me even more addicted was this picture.

I was in a daze for about three hours on this picture and made a lot of assumptions and calculations. In fact, it is not new knowledge. I know how to control the balance by adjusting the grinder, and I also know the relationship between the freshness of coffee and extraction. But the difference is that I hope to integrate a new framework between this existing knowledge and the North American knowledge system.

Really is not any new knowledge, just through their own section of collation and share with you. Because it has a certain guiding significance for what I said earlier about Philharmonic pressure, French pressure, Italian style and later hand punching.

In my diary (http://www.douban.com/note/207243440/), I mentioned a key point, that 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% Murray 11%.

Filtered coffee feels 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?

Remember what I said in that diary? 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

TDS/DOSE (gram weight of powder)

There is a very important concept that 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?

[in theory, if you find that the flow rate slows down during extraction, it will be a sign of excessive extraction. You can either thicken the grinding degree or reduce the amount of powder. But if the extraction rate is TDS/DOSE and you reduce the denominator, isn't the extraction rate even more excessive? Let's answer this question in the coffee group.]

I know that if I touch these for the first time, I will feel a little dizzy. Let's start with a topic.

Suppose:

The amount of powder is 20g.

Hand flushing with 350ml (g) water

And get about 300g of hand-brewed coffee

We detected it with a concentration meter, and we got a concentration of 1.2%.

We know it's TDS% = TDS / Coffee Weight. You already know it's 1.2%.

Next, we can know how many grams of soluble matter are in it.

It is 300g coffee with a concentration of 1.2%, then the soluble matter is:

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 lower limit 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 I said 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. ;)]

-- take a break from class.

These are also required courses for me to learn in the early days. I will 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.

Michael, ask me, if you change the amount of powder or water, your concentration (TDS/Coffee weight, the concentration will change due to the amount of coffee powder), the extraction rate (the amount of TDS/DOSE powder has changed, but the dissolved matter has also changed), how can you judge that how much of this factor has changed? I know, it 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.

The longitudinal axis is the concentration ratio, namely TDS/Coffee weight.

The horizontal axis is the extraction rate, or TDS/Dose.

Divide:

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

We asked TDS out, and we got it.

Dose / Coffee Weight

So this line represents the ratio of coffee powder to coffee gram weight. That's 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. Then the angle of this slash is that if you do not shift 15 g, the concentration will rise by 1 g, 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're fixed,

The water temperature is 94 °.

The amount of water is 350g

The powder of coffee weighs 20g

In fact, as long as we adjust one parameter, the thickness of the degree of grinding, we can make the concentration point of the extraction slide along this oblique line and enter the scope we need.

If, we get coffee concentration of only 1.1%. We can know

TDS is 300g * 1.1%, that is 3.3g

The extraction rate is 3.3 stroke 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

TDS is 300g * 1.5% or 4.5g

The extraction rate is 4.5 stroke 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. (I actually tried to improve this method according to my own way of learning. I'll talk about it next time.)

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 have to at least judge from the taste what kind of taste is excessive extraction and what kind of taste is insufficient extraction. At the very least, baristas themselves should be based on their own senses, right?

Finish

Postscript: although this article thinks it is of great significance, it is not really its own invention. Just a few years of their own learning process plus a lot of elders on demand advice. What is most touching is what Michael often said at the end. We all understand these reasons. Isn't it a pleasure for everyone to have a good operation?