Some things about coffee bean grinder Common questions and parts answers of Italian Coffee Grinder

The importance of grinder

First of all, I think it is necessary to explain the importance of the grinder. In a sense, the grinder plays a bigger role in the espresso machine than the coffee machine itself has always liked:

What exactly is the coffee machine for?

As mentioned earlier, the three main functions are extracting coffee, milking, and heating water.

But today, since we are talking about grinders, I intend to talk only about this part related to extraction. The function of the coffee extraction machine is obvious. At a high temperature of about 90 degrees, nine air pressures take about 30 seconds to extract coffee. Objective to embody the unique style of espresso as much as possible through the extraction of 30 seconds.

Here are a few parameters, usually, you can't change, or you don't change at will. (of course, some coffee machines can adjust all the parameters of LaMarzocco's Strada, Slayer at any time:

* Water temperature is mainly reflected in the level of temperature and the change of temperature.

* barometric pressure can participate.

* flow rate per unit time, different brands of coffee brewing head flow rate is different. In a practical sense, the coffee machine has 1.5 parameters that we can change.

* extraction time most machines can manually control the extraction time

* Water temperature stability sets the water temperature stability by half, because it only depends on putting an appropriate amount of water before extracting coffee to prevent the initial water from overheating. Only one and a half parameters can be accomplished by adjusting the coffee machine, so what are the remaining parameters that baristas can do?

In fact, there are many, many, the control of the amount of powder, the thickness of coffee powder, the power and angle of pressing powder, especially the power of pressing powder. I have mentioned that it is negligible compared with 9 atmospheric pressure, as long as the powder is pressed tightly each time.

So the two crucial parameters, the control of the amount of powder and the thickness of coffee powder, combined with the above-mentioned controllable parameters, are basically the vast majority of baristas' work. These two parameters are closely related to the grinder. This is why many baristas prefer a cheap coffee maker, but the requirement of the grinder is very high. There are many kinds of grinders on the market. From manual to electronically controlled tapered blades. But for espresso, the grinder is the most demanding. That's why.

First talk about two basic concepts, insufficient extraction, that is, the flow of water through the coffee powder is too fast, or the temperature is too low to fully extract the flavor of coffee. Excessive extraction, on the contrary, coffee water stays in coffee powder for too long, or the water temperature per unit time is too high, resulting in coffee flavor or other flavor over-extraction. Continue to look at the uniform thickness of grinder A powder. First of all, espresso is done at 9 atmospheres. Therefore, the pressure of water is very high, and the gap between coffee powder must be very small. Otherwise, the unimpeded flow of water under high pressure between very coarse powder particles will result in insufficient extraction.

Secondly, because of the high temperature and high pressure extraction, any flavor will be magnified. If you use a non-Italian grinder to grind, the size of the powder is very different, which will cause excessive extraction of some coffee powder (small particles) and insufficient extraction of some coffee powder (large particles), so the resulting flavor is easy to produce miscellaneous smell. But is it always good to have a consistent coffee powder? This issue was hotly discussed about a few years ago. Because at that time, apart from the difference in rotational speed between cone blades and blades (which will be mentioned later), many people began to wonder why the coffee tastes different between the two. In blind measurement, in the blind measurement of similar cutter head size (robur and royal), the conical knife robur will be better than the flat knife royal?

Robur and its conical knife

Royal and its flat knife

What is even more surprising is that the particle uniformity produced by the cone knife is far worse than that of the flat knife!

To explain this problem, you can compare it with the example of steak. Unlike Chinese food, fried steak is layered, often well-done on the outside, half-done on the inside, and even bloody. But the advantage is that the taste is rich (complex), which can be superimposed layer by layer.

Similarly, coffee, like red wine as an acquired taste food, can not only be achieved through the variety of beans, mixed beans or baking (temperature curve, happy Vs slow heat, light baking Vs deep baking), but also through the grinder to produce a certain degree of uneven to reflect its rich taste. Of course, there must be a range of such differences, because excessive differences will give rise to the problems of both over-extraction and under-extraction. In this category, I have seen the data show that the particle size is about 20% and 30%.

The problems of grinding speed and heat energy range from raw beans to baking to grinding into powder and making coffee. The closer to the finished product, the more "fragile" the coffee is. As long as the raw beans are properly stored, there will be no problem with them for a few months. Roasted coffee beans had better be finished within 3 weeks. If it is extracted under low pressure, one week is the best life cycle. If it is made of coffee, it will lose 50% of its fragrance in less than two minutes. The grinding process of the grinder will produce a lot of heat. Ground coffee is easy to oxidize and volatilize when exposed to air. (that's why coffee beans are ground.)

Therefore, the heat generated by the speed of the grinder has a considerable impact on coffee. In other words, the slower the speed of coffee, the less heat will be generated and the rate of oxidation of coffee will eventually decrease, but there is a paradox: "if the speed is slow, then the speed of flour will be slower." If the coffee shop is busy, don't you have to use a high-speed grinder? " Yes, but another way to achieve high output and low speed is to use a large diameter blade. Due to torque, grinding can be completed quickly even if the rotational speed is very low. For example, mazzer's current flagship product robur,73mm knife head can basically produce 20g powder in about 4 seconds, while the rotational speed as low as 450RPM (it takes about 20-30 seconds for Mazzer supper jolly 1500RPM to complete 20g powder production) has mentioned that the speed of the grinder has two effects on coffee, one is the speed of the powder itself, and the heat generated.

In fact, there is also a question about operation. Although the coffee powder is fast and can serve the public in a timely manner, I personally do not recommend buying a high-end high-speed grinder if it is not a very busy coffee shop. Because the waste of powder is quite large.

This kind of waste is mainly reflected in several aspects:

1. A good coffee shop, a good barista, if he doesn't make coffee for a period of time, he will clear the powder every time he starts to make coffee, thus removing the coffee powder clogged in the powder channel. Often, the more efficient the grinder is, the more powder will be accumulated, and the more waste will be caused.

two。 Often the faster the grinder pulverizes, the better skills are needed to prevent waste. What I want to emphasize here is that I take whether I can make 200 cups of coffee a day as whether the coffee shop is busy, that is, about 2.5-3kg of coffee beans a day.

At the same time, it should be mentioned that the fast grinder can adjust the powder quantity more accurately, which will be detailed in the next chapter. C manual Vs electric or powder quantity control problem about a few years ago, when the robur electronic control version appeared, many people once cheered, because when the timing was controlled at 0.05s, it seemed that a truly accurate and efficient grinder came out in less than 4 seconds. There has never been a tendency to belittle electronic control. In fact, I personally have a robur e grinder.

However, what I have found is that the over-reliance on electronic control is very serious, both at home and abroad. First of all, let's look at the principle of electronic control. It's simple, by timing. The running time is controlled in the unit of 0.05 seconds, thus the control of powder quantity is completed. Reality: after experiments, the error can be as high as 0.8g when powdered for 5 times at the same time. What kind of concept is this? Only 0.5g of powder is equivalent to a double handle, which can completely change the flow rate and flavor of espresso. In the flavor evaluation, only one more tap on pressed powder, the amount of powder can be about 0.3g more, the fullness of coffee will be significantly improved.

Therefore, the topic here is not that the robur electronic control board is not good, but that the electronic control board does not mean that you can rely too much on the accuracy of electronic control. You still need to fine-tune it through the powder distribution link. Secondly, the electronic control board also has a more troublesome is to adjust the flow. Because when the thickness is adjusted, the speed of powder production in the same unit time is not the same. Therefore, after the thickness is adjusted, the time of powder production should be adjusted accordingly.

I won't talk about this in detail here for the time being. Of course, the electronic control board is not useless. The biggest advantage, I personally think, is to give up the powder bin and reduce the residual powder as much as possible. In addition, due to the abandonment of the powder bin, the coffee powder falls vertically, which avoids the waste of powder to a certain extent. If the electric control board is not a tool that can be over-relied on, then the grinder of the hand control board still has a very competitive advantage even today. Through reasonable operation, the amount of powder can still be accurately controlled. This point will also be discussed in detail in the next chapter. The end grinder has an important impact on both baristas and coffee. The training of many high-end baristas abroad is closely related to the grinder. This chapter can only briefly talk about the parameters of the grinder. But the points mentioned do not emphasize which kind of grinder is the best one. More importantly, how these characteristics of the grinder affect coffee. Of course, these parameters also influence each other.

There are more words described here, which will be boring compared with the evaluation of coffee and flower pulling in the past. But as far as I understand it, it is the most important part of coffee extraction.)

Not as a barista, this is the end of knowledge, in fact, there are many ways to improve the room for coffee. But through the summary of the past few years, this link is a return.

It used to be from senses to data, but here it is to send data back to the senses. Many friends know that if you look at whether the extraction is reasonable, it is mainly aimed at the flow rate of the extraction.

Generally speaking, in 30 seconds, 30ml (including creama) describes the various characteristics of the grinder. But in fact, in the end, it is necessary for the barista to adjust, that is, the two main parameters mentioned earlier, the amount of powder and the degree of grinding. If:

1. If the amount of powder is more, the flow rate will be slow, because the more powder will provide more resistance.

two。 Fine grinding, the flow rate will also be slow, thinking that fine grinding will increase the density, thus reducing the gap and providing more resistance.

Here we can draw a conclusion that the amount of extraction can be controlled by adjusting the amount of powder and grinding degree. But have you considered a very fundamental question here? On the other hand, the degree of grinding and the amount of powder can be combined differently at a flow rate of 30 seconds 30ml. Then, even if the flow rate is correct, the flavor may be different with different settings of grinding degree and powder quantity!

In fact, what I said is almost all the tasks of baristas. That is, in the case of a reasonable flow rate, through fine-tuning to achieve the due flavor.

In this process, in addition to the amount of powder and grinding, we do not put in the water temperature of pressing powder and coffee for the time being, but we need to add another crucial parameter:

That is, the freshness of coffee.

Because the fresher the coffee, the higher the carbon dioxide content, the higher the resistance. Okay, let's sum it up again:

1. The amount of powder, the more powder, the greater the resistance.

two。 Degree of grinding, the finer the grinding, the greater the resistance.

3. Carbon dioxide, the same amount of coffee powder, the fresher the coffee, the greater the resistance.

Therefore, at the same flow rate, coffee at a specific time, we need to set the grinder, as well as more and less grinding to ensure that not only the flow rate is moderate, but also the flavor is more suitable. Here are a few questions:

1. What kind of flavor is the more suitable flavor?

two。 Which taste of coffee is determined by the amount of powder, the degree of grinding and carbon dioxide?

3. How to adjust accurately?

Unfortunately, the first problem, although today's baristas have specific instruments that can be quantified by data. But in the final analysis, there needs to be a complete evaluation standard. This standard is not an absolute value, but a taste framework. I can't use words to describe how good coffee is. This requires everyone to practice face to face together. But in order to better describe the following article, I will temporarily take the two most important characteristics of espresso as indicators of whether it is well-intentioned concentration: richness and balance. In fact, rich and balanced, in order to facilitate understanding, and then simplify it, we use body and flavor to reflect.

Although many flavor have chocolate, syrup, etc., but most of the flavor will be mainly acidity, that is, sour taste. Therefore, the equilibrium mentioned here is determined by body alcohol and acidity acidity.

Relatively speaking, in the process of coffee extraction, the flavor is dissolved in the water at the beginning of extraction by high-pressure hot water. After that, the dissolution rate will have a large attenuation.

On the other hand, the alcohol content is a relatively peaceful and uniform extraction process. That is, the alcohol content will increase at a uniform rate with the time of coffee extraction. In short, at the beginning of the extraction, the extraction of most of the flavor parts will be completed in the initial 5-8 seconds, and the longer the alcohol content, the higher the alcohol content. The extraction rate of general coffee will not exceed 40%. [suggested experiment 1: if you have the opportunity to do an experiment, divide the 30-second extraction into three stages, the coffee will be very sour in the first 10 seconds, the taste will be moderate in the middle 10 seconds, and the coffee will be bitter in the last 10 seconds. ]

So back to what I said earlier, if you want to produce 30ml espresso in 30 seconds.

The degree of grinding is fine, which means that the amount of powder should be relatively small. When the grinding degree is adjusted finely, the area of coffee in contact with water increases, which will improve the acidity of coffee. But what is sacrificed is the reduced amount of powder, that is, mellowness.

On the other hand, if the grinding adjustment is very thick, then in order to ensure that there is 30ml espresso within 30 seconds, it is necessary to increase the amount of powder. Therefore, it also means that although the density of coffee powder is reduced and acidity extraction is reduced, at the same time, the thickened pressed powder can increase its mellowness through layer by layer extraction.

Therefore, it is obvious that baristas can balance the taste by adjusting the amount of coffee powder and the degree of grinding.

But in fact, it is difficult. Because we haven't put in another parameter, coffee freshness.

If the coffee starts to make espresso as soon as it comes out of the oven, the huge resistance caused by carbon dioxide has to set the grinder to be thicker.

Because if the setting is too fine, the amount of powder will be greatly reduced, and the mellowness of the coffee will be greatly reduced.

To take another extreme example, if a lot of carbon dioxide is emitted four weeks after the coffee is roasted, the grinding degree must be thickened to ensure that the flow rate is correct by increasing the amount of powder.

This is why it can be explained that espresso has a longer awakening period. It's not that the fresh coffee is better, but that we need a well-balanced cup of coffee.

It is recommended that in experiment 2, make a cup of coffee with perfect flow rate on the third day after a bag of coffee beans are baked. Then compare the flow rate after three weeks. If you adjust it, you can obviously see the difference in terms of taste, flavor, and setting.]

Through the setting of the grinder, we can adjust the thickness and powder quantity. So how accurate does the powder setting need to be?

Generally speaking, 0.5g is enough to change its flow rate and flavor.

As for the adjustment of powder quantity, sometimes the grinder with large cutter head only needs to tap gently with a powder hammer, and the change of thickness can also change its flavor and flow rate. What's more, each cup has to be made the same, so we need a series of methods and tools to help us achieve it.

What has just been described is actually the core topic of espresso in the world over the past decade, that is, the relationship between extraction and flow rate as well as flavor.

Here we have to mention the contribution of the Australian coffee industry to the world coffee. Melbourne, in particular, was rated by the World Coffee Association as the country with the best coffee environment in the world this year. If you pay attention to the competitions in recent years, basically, Australian baristas can enter the top three in the World Barista competition. And careful friends can find that even if they come from different institutions and coffee shops every year, their methods are the same. This is because many colleagues have conducted a series of studies and studies to ensure that what they are doing is the most scientific and reasonable.

I cannot describe the powder quantity and grinding control in detail in this chapter. Because if you go on, it's beside the point. And the focus of this article, as I said earlier, when we know the characteristics of the grinder and its function. We actually understand the purpose of the tool, and in the end, in order to present a satisfactory cup of coffee to ourselves and our customers.

Source:

The blog of coffee man Lu Xiansen