Powder quantity control

To my knowledge, I have seen amazing flowers in China, countless players who are interested in machinery, and many fans who have a few treasures about coffee producing areas.

However, when I see many people in the extraction of Italian concentrated, do not distribute powder, do not control powder, or even taste judgment, I do not understand.

If the extraction is not proper, no matter how beautiful the flower will only make the coffee spoil, if you can't control the amount of powder, the production, the quality control can't be controlled, and the quality control can't be controlled, the so-called flavor description, spy on the so-called coffee bean species is actually impossible to talk about.

From the sensory point of view, you need to know the balance of sour and bitter, and to achieve the balance of sour and bitter, and even extract enough sweetness, on the one hand, you have to know how to adjust the grinding degree, and on the other hand, you have to know how to adjust the powder amount accordingly.

(Actually, there's another one, extraction time, but that's not today's topic)

With regard to the adjustment of grinding, any study of coffee basics (whether hand brewed or Italian) is a compulsory course.

However, the problem came, we did not talk much about the amount of powder control, or only compared to the mechanical standard of 14g double, or powder warehouse full,"crack" twice, smooth.

In fact, the adjustment of powder quantity is as important as the degree of grinding, and today I will spend a lot of time describing the importance of powder quantity control.

In the past we knew:

1. Strength determines how strong the coffee is. It is soluble matter that determines concentration.

(It is worth mentioning that non-soluble substances can also improve coffee body, I fully agree, but this time I only focus on soluble substances as the main reason)

And its calculation can be measured by concentration light refractometer:

TDS%= TDS/Coffee Weight

that is, that percentage of soluble matt is the gram weight of soluble matter divide by the total weight of coffee

2. And this soluble fraction is the amount of powder that comes from coffee.

So, we can get the extraction yield from this, that is,

EY= TDS/DOSE

That is, the gram weight of the dissolved matter divided by the amount of powder used, we know how much percentage is extracted.

In most cases, whether espresso or hand-brewed coffee, the reasonable extraction rate is 18-21%.

Now let's start with the amount of flour as the core and see how the amount of flour affects coffee flavor.

Before that, we used the high-end Mazzer Robur electronic control grinder as an example. If the powder is not distributed, the minimum powder amount and the maximum powder amount can have a difference of about 2.3g. We simply take this as an example, 2.3g, it seems that only "10%" of the powder amount difference, we will have how to make differences.

Here, we make another assumption, that is, according to the traditional production method, to reach 60ml double espresso that is to stop extraction.

At the same time, for the convenience of calculation, it is assumed that the gram weight of 60Ml coffee is the same.

(This is a limitation, just for ease of understanding)

Here, we assume parameters

Powder 1: 17.7g

Powder 2:19g

Extract 60ml of coffee

Weight: 38g

And the coffee is fresher and more standard medium roast.

Also, we did not have any problems pressing the powder and the extraction was uniform.

We can get the following parameters, as shown in the figure:

chart

This graph tells us that the green area represents the reasonable extraction range.

For example, for 19g of powder 1, when we have a concentration of 9%, the corresponding extraction rate is 18%. (38*0.09/19) and at the same concentration, 17.7g powder, the extraction rate will be higher, i.e. 19.3%.

The reason is obvious, coffee weight is the same, the same concentration is extracted with 19g powder, the other is 17.7 g, obviously, 17.7 g powder utilization rate is high.

But in this picture, we can clearly see that if 17.7g of powder is used and 38g of coffee weight is guaranteed, the concentration cannot exceed 10.25%, even if the espresso required concentration can reach 11%. Perhaps it takes time for you to digest the data, but I can give you a few summaries and revelations:

Summary of Powder Control Consistency

1. In the case that other parameters of each extraction are consistent, your powder amount cannot be guaranteed to be consistent every time and reach 10% error. If you make a high powder amount, you will obviously extract less than the powder amount.

2. If you don't extract enough, it's likely to make the coffee a lot more sour.

Summary of fine adjustment of powder control

3. If we are adjusting the machine, we will judge whether the sour and bitter balance (of course, I assume you are a serious barista). We do not necessarily have to adjust the grinding degree first, because each time you adjust the grinding degree, you need to empty the original powder.

4. As you can see from the graph, assuming that changing the amount of powder makes the EBF line (17.7 g--->19g) steeper (the angle becomes larger), then, at the same concentration, you can reduce the extraction rate, which may make the coffee more sour and less bitter.

(Note that this is a possibility, and there are many other factors that determine the perception of sourness.) But from the extraction rate point of view is a common way, at the same time, I want to emphasize that it is not sour or bitter which is better, but to achieve a balance between sour and bitter and control the amount of powder)

As shown in the figure, the increased amount of powder makes the coffee that was originally over-extracted become a normal extract.

Revelation:

There is also a very important revelation here, generally the same kind of coffee beans, the deeper the roasting degree, the higher the corresponding mellow degree of the same extraction parameters.

Conversely, in today's era of light baking, light baking espresso can reflect rich floral, citrus and other fruit flavors. But the sour-bitter balance, as well as the full body, is a great challenge. The extraction efficiency of light roasted coffee beans is lower than that of dark roasted coffee beans.

That is, the same amount of powder, the same extraction time, the concentration of light baking tends to be low. A low concentration can make a light roast coffee full as a hard mark.

From this picture we can see that if only 17.7g of powder is used, if it reaches 11%, it already means excessive extraction. Therefore, this more or less can explain that if the filter bowl is small and the powder content is not much, it is not recommended to try light roasted coffee beans.

This also explains why Axil, a Melbourne light baking powerhouse, uses a 22g VST filter bowl to make a double espresso! A 22g bowl could actually add 25g of powder! As a barista, first of all, we should naturally know how to taste and judge, and then adjust the balance of sour, bitter and sweet tasted by ourselves, as well as the mellow degree.

And the amount of powder, at least in this chapter, can be seen as an important tool. Of course, I used a 10% margin of error today to express this question.

In fact, an error of 0.5 g is enough to change the flow rate, and if you can control your powder to an error of less than 0.3 g, you may:

1. to give consistency to every cup of coffee.

2. Learn to fine-tune its flavor accordingly.

3. By combining powder adjustment with understanding the impact of grind and extraction time on coffee flavor, you can give coffee more control. Below, I'm going to take the development of fine coffee making in Australia as an axis and talk about how they control the amount of powder.

Scottie invented the scraper four years ago, and this invention also led to later research on powder control.

From what little I know about him, I still consider him one of the most influential baristas in Australia. It is not easy to become the world champion of flower pulling, but it is even more valuable to go from the world champion of flower pulling to the third place in the world of Bristol.

And on top of that, his understanding and sharing of coffee making has kept Australia relatively ahead of the curve on a systematic basis for a relatively long time, which is all the more precious.

And today, I'm talking about the scraper he invented in 2006.

Yes, from the picture. Scraping blades are a group, the radians are different. Today it doesn't seem to be innovative in any way. But if we think about the relationship between powder quantity and extraction, in fact, he gives us a very systematic way to make it, even with some conceptual innovation.

Around the beginning of the 21st century, espresso coffee was made according to dr illy's golden theory. 9 atmospheres, 7g powder, 30ml extracted in 25 seconds to 30 seconds.

Therefore, when the amount of 7g powder is fixed and 30ml is extracted, it should be said that extraction is more reasonable. According to the conventional orthodox practice, coffee ground into powder, put into powder bin standby. Wait for the guest to order coffee, the powder bin handle clap once, a split groove is about 7g, if it is double, clap twice.

Then, it was directly pressed into powder and extracted. I think that those who learned the basics of making coffee in the early days should be familiar with this process. And this method, can not be wrong, and from the perspective of popularity, there is no concept of boutique coffee in the early stage, or very practical.

However, we overlooked a very important factor in the production, the relationship between coffee freshness and carbon dioxide.

Carbon dioxide is a love-hate thing for coffee. Its greatest benefit is that it prevents coffee oxidation, but at the same time, too much carbon dioxide makes coffee over-expand and hinders the extraction process. So we often have a concept called the waking bean period. That is, coffee that has just come out of the roaster, if it is used to make espresso, it will sit for about 3-4 days before starting to make.

Because if it's fresh out of the oven, too much carbon dioxide causes the coffee cake to swell, so you can't put too much powder, and too little powder causes us to over-extract (remember the formula, extraction rate, extracted substances divided by powder), and there should be no spicy taste.

In this graph, we can see the rate at which carbon dioxide evaporates from coffee beans as they are ground. (The horizontal axis is hours, the vertical axis is CO2 volatilization) It is obvious that once ground, CO2 volatilization is almost instantaneous.

Basically, in five minutes, you lose 50 percent of your carbon dioxide.

In the form of coffee beans, it takes three weeks to lose 50%.

And that's why, in coffee classes, in coffee shops, there's a concept called "fresh grind," which is only part of the story, and this picture gives us a bigger insight:

Even though it is a coffee bean, with the evolution of time, carbon dioxide is constantly emitted, and their freshness is not the same, so the powder control of coffee is a dynamic.

That is, after the waking period, when coffee is full of flavor and carbon dioxide, we may not need too much powder to achieve the flavor we need.

After about two weeks, the CO2 emission was so high that we needed more powder to compensate and avoid over-extraction.

Therefore, as a barista, like the grinder setting, it is not necessary to remember how much g coffee powder is, but more importantly, according to the time difference, make corresponding adjustments.

The conclusion is that in the process of dynamically adjusting powder quantity, relative powder control is more meaningful than remembering gram number. What is the meaning of this?

If I extract 30ml of espresso in 25 seconds today, it feels not mellow enough, even bitter. A possible indication of this is that the solubles are not very much (low concentration), but they are over-extracted (high extraction yield).

We may increase the amount of powder slightly to increase its body, and increase the amount of powder, so that more powder can be extracted and thus reduce the extraction rate.

So I only need about 0.5g of powder? It's not how much powder I used, it's how I can increase it slightly.

Speaking of which, Scottie's scrapings explain it.

Different arcs, meaning different amounts of powder can be scraped off. A flat blade scrapes more powder than a curved blade. And that's exactly what I'm talking about, the concept of relative powder control.

And you can notice that the arcs are different.

Although the structure of the powder scraper is very simple, and today's coffee world, there are other ways to replace it. But the concept behind it still has its value.

We didn't throw out Dr. illy's concept, but we added a freshness variable, and with an adjustable parameter, we could fine-tune the amount of flour.

More importantly, the amount of powder has also become one of the skills that today's baristas need to know and master. And that controls the two things I said earlier:

1: Maintain consistency of powder control every time.

2: Judge according to the taste, so as to make controllable adjustments.

I sincerely hope that everyone can spend some thought on powder control.

Trust me, this is going to be a big improvement on coffee making. Around 2008, Scottie himself stopped using his own scraper.

Because scraping blades also have undeniable shortcomings. As I said earlier, fresh coffee often doesn't require much powder.

Therefore, we use the most prominent curved blade to control powder. The problem is that whether it is in WBC or in normal operations, this means that we will have to make a trade-off between quality and waste. This is because the powder we scrape off will be judged as a waste in the competition. It must be more than 1g. In operation, you have to keep improving, and you will not put it into the powder bin.

A good barista does not lie in his skill, or even in his senses, but in how to serve the products of nature to mankind, and to improve and learn for this purpose.