Incomplete arrangement of data 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's more surprising is that the particle uniformity produced by cone knife is far worse than that of flat knife!

To explain this, compare it to steak. Unlike Chinese food, fried steak has layers, often well-cooked outside, medium-cooked inside, and even blood. But the advantage of this is that the taste is complex and can be layered.

Similarly, coffee, like red wine, as an acquired taste food, in addition to the variety of beans themselves, mixed beans or roast (temperature curve, happy Vs slow, light vs deep roast) to achieve, but also through the grinder to produce a certain degree of unevenness to reflect its rich taste. Of course, there must be scope for such differences, because excessive differences can lead to both over-extraction and under-extraction problems. In this category, I have seen data showing that the particle size is about 20%-30%.

The speed and heat of grinding go from green beans to roasting to grinding to coffee. The closer to the finished product, the more "fragile" the coffee. Raw beans, as long as stored properly, a few months of storage is no problem. Roasted coffee beans are best consumed within 3 weeks, and if it is low pressure extraction, one week is the best life span. If it's made coffee, it loses 50% of its aroma in about two minutes. A lot of heat is generated during grinding. Ground coffee is easily oxidized and volatilized when exposed to air. (That's why coffee is made.)

Therefore, the heat generated by the speed of the grinder has a considerable impact on coffee. In other words, the slower the coffee is rotated, the less heat is generated, and the final rate of coffee oxidation will decrease. However, there is a paradox here: "If the rotation speed is slow, the speed of powder extraction will be slow." If the coffee shop is busy, don't you have to use a high-speed grinder?" That's right, but there's another way to achieve high output and low rpm, which is to use a large-diameter blade. Due to the torque, grinding can be completed quickly even at low speeds. For example, Mazzer's current flagship product, robur, 73mm large disc, can basically produce 20g of powder in about 4 seconds, while the speed is as low as 450RPM (Mazzer's upper jolly 1500RPM completes 20g of powder. It takes about 20-30 seconds).

In fact, there is an operational problem. Although coffee powder speed, can be very timely service to the public, but if not very busy coffee shop, I personally do not recommend buying high-end high-speed grinder. Because the amount of powder wasted is considerable.

This waste is mainly reflected in several aspects:

1. A good coffee shop, a good barista, if you haven't made coffee for a while, will clean the coffee powder every time you start making coffee, thus clearing the coffee powder blocking the powder channel. Often the more efficient the grinder, the more powder will accumulate, and the more waste will naturally be caused.

2. Often the faster the grinding machine, the better the skill to prevent waste. I want to emphasize here that I take whether I can make 200 cups of coffee a day as the boundary of whether the coffee shop is busy, that is, about 2.5-3kg of coffee beans a day.

It should also be mentioned that the fast grinding machine can adjust the powder amount more accurately, which will be described in detail in the next chapter. About a few years ago, when the robur electronic control version appeared, many people once cheered, because when the timing control was in 0.05 seconds, the powder amount of 20g in less than 4 seconds seemed to mean that a truly high-precision and high-efficiency grinding machine came out. There was never a tendency to belittle electronic control. I actually own a robur e grinder myself.

However, what I found is that both at home and abroad, excessive reliance on electronic control is very serious. First of all, let's look at the principle of electronic control. It's very simple, by timing. Control of the powder amount is accomplished by controlling the running time in units of 0.05 seconds. Reality: Have done experiments, set the same time, continuous powder 5 times, the error can be as high as 0.8g. What kind of concept is this? Just 0.5g of powder is equivalent to two handles, which can completely change the flow rate and flavor of espresso. In the flavor evaluation, only need to tap the powder cake once more, the powder amount can be about 0.3g more, the fullness of coffee will be significantly improved.

So the topic here is not that robur boards are bad, but that boards don't mean you can rely too much on precision. You still need to fine-tune through the powder distribution link. Secondly, the electronic control board also has a more troublesome adjustment process. Because when the thickness is adjusted, the speed of powder in the same unit time is different. Therefore, after the thickness adjustment, it is also necessary to adjust the powder time accordingly.

I will not discuss this in detail here. Of course, the electronic control board is not useless. The biggest advantage, I personally think, is to give up the powder bin and minimize the residual powder. Also, because the powder bin is removed, the coffee powder falls vertically, to a certain extent avoiding waste when receiving powder. If the electronic control board is not a tool that can be relied on excessively, then the grinding machine of the manual control board still has a competitive advantage even today. Through reasonable operation, it is still possible to accurately control the amount of powder. This will also be discussed in the next chapter. End grinders are critical to both the barista and coffee. Foreign high-end barista training, are closely related to the grinder. This chapter deals only briefly with grinding machine parameters. But the few points mentioned do not emphasize which grinder is the best grinder. More importantly, how these characteristics of the grinder affect coffee. Of course, these parameters also affect each other.

(There are many words described here, and compared with the past evaluation coffee, pull flowers will be boring.) But as far as I understand it, it's the most important part of coffee extraction.)

Not as a barista, this is the knowledge of the end, in fact, there are many ways to improve the coffee space. But through the summary of these years, this link is a regression.

Before, it was from senses to data, but here it is sending data back to senses. Many friends know that if you look at whether the extraction is reasonable, it is mainly for the extraction flow rate.

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

1, more powder, the flow rate will be slow, because more powder will provide more resistance.

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

Here we can draw a conclusion that by adjusting the powder amount and grinding degree, it is possible to control the extraction amount. But have you considered a fundamental question here? Conversely, at a flow rate of 30 seconds and 30ml, there can be different combinations of grinding degree and powder amount. Then, even if the flow rate is correct, the flavor may be different with different settings of grinding degree and powder amount!!

In fact, I said this point, almost all the tasks of the barista. That is, under the condition of reasonable flow rate, the proper flavor can be realized by fine adjustment.

In this process, in addition to the powder amount and grinding, we temporarily do not put in the pressure powder, coffee water temperature, but to add another crucial parameter:

The freshness of coffee.

Because the fresher the coffee, the higher the CO2 content, the higher the resistance. All right, let's summarize this one more time:

1. Powder amount, the more powder amount, the greater the resistance.

2. 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 certain time, we need to set the grinder, as well as the amount of grinding, to ensure that not only the flow rate is moderate, but also the flavor is more suitable. Several questions arise:

1. What flavor is more appropriate?

2. The amount of powder, the degree of grinding, and the carbon dioxide each determine the taste of coffee.

3. How to adjust accurately?

Unfortunately, the first question, although today baristas have specific instruments that can quantify data. But in the end, there needs to be a complete evaluation standard. This criterion is not an absolute value, but a taste framework. I can't put into words how good coffee is. This requires face-to-face practice. But in order to describe the rest of the article, I'll take two of the most important characteristics of espresso as indicators of well-intentioned espresso: richness and balance. In fact, rich and balanced, in order to facilitate understanding, and then simplify it, we use alcohol (body) and flavor (flavor) to reflect.

Although many flavors have chocolate, syrup, etc., most flavors will be based on acidity, that is, sourness. Therefore, the balance mentioned here is determined by body alcohol and acidity.

In contrast, in the extraction process of coffee, the flavor is reflected in the dissolution of high-pressure hot water into the water at the beginning of extraction. There is then a large decay in dissolution velocity.

Alcohol, on the other hand, is a relatively peaceful and uniform extraction process. That is, the alcohol content will increase uniformly with the extraction time of coffee. In short, most of the flavor components are extracted within 5-8 seconds at the beginning of extraction, and the alcohol content increases with time. (The extraction rate of coffee generally does not exceed 40%). [Suggestion Experiment 1: Everyone has the opportunity to do an experiment. Divide the 30-second extraction into three sections. The coffee will be very sour in the first ten seconds, moderate in taste in the middle ten seconds, and bitter in the last ten seconds.】

So back to the previous point, if you want to produce 30ml of espresso in 30 seconds.

The grinding is fine, which means that the amount of powder should be relatively small. The grinding degree adjustment is fine, and the area of coffee contact with water increases, which will improve the acidity of coffee. But the sacrifice for this is the reduced amount of powder, that is, alcohol.

On the other hand, if the grinding adjustment is very coarse, then in order to ensure that there are 30ml of Italian coffee in 30 seconds, it is necessary to increase the amount of powder. Therefore, this also means that although the coffee powder density is reduced and the acidity extraction is reduced, at the same time, the thickened powder cake can increase its alcohol by layer extraction.

Therefore, it is obvious that the barista can achieve the purpose of balancing the taste by adjusting the amount of coffee powder and the degree of grinding.

But it's actually quite difficult. Because, we haven't put another parameter in yet, coffee freshness.

If you start making espresso right out of the oven, the CO2 creates so much resistance that you have to set the grinder to a coarser setting.

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

To take another extreme example, if the coffee is roasted for 4 weeks and the carbon dioxide is emitted a lot, the grind must be coarser at this time. Make sure to increase the powder amount to ensure the correct flow rate.

This may explain why espresso coffee has a longer wake-up period. It's not that the fresher the coffee, the better, but that we need a well-balanced cup of coffee.

[Suggestion 2: Make a cup of coffee with perfect flow rate on the third day after a packet of coffee beans is baked.] Then compare the flow rates three weeks later. Reconditioning can be very obvious from the taste, flavor, and settings to see the difference]

Through the grinding machine settings, we can adjust the thickness and powder amount. How accurate is the powder setting?

In general, 0.5 g is sufficient to change its flow rate and flavor.

As for the adjustment of powder quantity, sometimes the grinding machine of large knife disk only needs to tap lightly with powder pressing hammer, and the change of thickness can also change its flavor and flow rate. What's more, each cup has to be done the same, so there needs to be a series of methods and tools to help us achieve it.

What has just been described is actually the central topic of the world's espresso over the past 10 years, namely the relationship between extraction and flow and flavor.

The Australian coffee industry's contribution to the world coffee industry must be mentioned here. Melbourne, in particular, has been named the best coffee environment country in the world by the World Coffee Association this year. If you pay attention to the competitions in recent years, basically the world Brista competition, Australian baristas can basically enter the top three. And careful friends can find that their modus operandi varies from year to year, even though they come from different institutions and coffee shops. And that's because a lot of people in the same industry have done a lot of research and research together to make sure that what they're doing is the most scientific and rational thing possible.

I can't describe the powder quantity and grinding control in detail in this chapter. Because I'm getting off topic. And the point of this article, as I said earlier, is that when we know the characteristics of the grinder and what it does. We actually understand the purpose of the tool, and ultimately it's to present ourselves and our customers with a satisfying cup of coffee.