Barista skills | Professional barista Handbook (3) strength of powder pressing, how to press powder

For professional baristas, please follow the coffee workshop (Wechat official account cafe_style)

For professional baristas, please follow the coffee workshop (Wechat official account cafe_style)

Many people admire the profession of baristas very much, and some people even aspire to become a barista. These ideas are not surprising, because baristas can taste all the most delicious coffee, and they can also do cool experiments with different drinks and use those super-expensive coffee machines.

But in fact, making coffee is not as simple as it seems.

First of all, if you want to be a barista, you must have enough knowledge about coffee. Some people think that most baristas don't need too much training to get on the job. But in fact, every barista is systematically and professionally trained, and they must understand every aspect of coffee shop operation, from table service to washing cups.

The most important ability a barista needs to have is the ability to handle multiple tasks at the same time. Baristas must keep taking orders at the same time to ensure that the foam is just right, and the amount of water from the coffee machine is accurate. An excellent barista should also be able to smile at all times while dealing with the special requirements of some special clients.

Professional barista Handbook

Author: Scott Rao translator: uncle Dewa

How to get started with professional baristas? Translation of the Handbook of Professional baristas (1)

Practical information | Translation of the Handbook of Professional baristas (2) Espresso grinding, powder filling and cloth powder

Continue with the second chapter.

Pressing powder

Pressing powder will lock the cloth powder, smooth the surface of the powder bed and eliminate the pores in the powder bed. Pressing powder can also make baristas feel the quality of filling powder, cloth powder and grinding.

The strength of pressing powder

Contrary to the common view, the author thinks that the strength of powder pressing has little effect on the velocity of flow. Once the pressing powder is completed with enough pressure, the pores in the powder bed have been eliminated, and adding more pressure powder will not have much effect on the extraction quality and flow rate. (note 6: many baristas overestimate the effect of heavy powder on flow rate. One of the interesting reasons is that when using the same powder amount and the same powder bowl, the heavy powder will make the powder bed more compact. Make the "space" between the coffee powder and the water distribution network larger. Since the space must be filled before the water can be pressurized through the coffee powder, more space can extend the time between the start of the pressure pump and the start of the extraction. This extension of time may cause baristas to overevaluate the effect of heavy powder on flow rate. The following two points can be proved:

1. The pressure created by pressing the powder is completely (or partially) released after the coffee powder is soaked.

two。 The pressure of about 50 pounds exerted by the barista when pressing the powder is dwarfed by the pressure pump of the coffee machine during extraction (7:9 atmospheric pressure ≈ 130.5 psi; the surface area of coffee powder in the 58mm powder bowl is 4.09 square inches; 130.5 x 4.09 = 533.7 pounds).

It's hard to say what good it is to press the powder with a lot of force, but it has at least two advantages: it puts less pressure on the barista's wrists and shoulders, and it's easier to make a full horizontal press (especially when using high-fit hammers and bowls. If the barista uses a lot of power to press the powder, the chance of the powder hammer and bowl getting stuck will be greatly increased, indicating that the powder hammer is not horizontal.

Knock or not?

With regard to powder pressing, the focus of the recent debate is whether it is necessary to hit the handle when pressing powder. The main percussion school believes that tapping can knock off the loose coffee powder that is squeezed to the edge of the powder bowl during the first pressing, and then press the coffee powder into the powder bed through the second pressing.

You need to measure whether the benefits of pressing that bit of powder back into the powder bed can make up for the potential harm caused by percussion. The tapping action breaks the closure between the coffee powder and the powder bowl wall, forming a channel around the powder bed. In the author's experience, it is almost impossible to close such a channel by pressing powder for the second time. Of course, not every knock may break the closure, but it's still not worth the risk. All in all: if a little bit of loose powder is a problem, it is only a small problem (I don't think it is a problem at all), while the passage between the powder bed and the powder bowl is a serious problem.

There is a female barista I admire who uses her wrists (like a champagne hammer) to make the powder bed more harmonious. If you have to knock, it looks a little safer than hitting with a hard handle of a pink hammer.

How to press powder

Gently hold the hammer with your hand and adjust the handle of the hammer until it seems to be an extension of your arm. Keep your wrists straight so that the bottom of the pink hammer handle is comfortably placed in the palm. This posture minimizes the pressure on the wrist, which is good for baristas who need to do hundreds of powder crushing moves a week.

Keep the powder hammer horizontal and squeeze gently on the powder pile. Then that's enough, there's no need to twist or press a second time.

After picking up the powder hammer, there may be some loose coffee powder on the wall of the powder bowl or on the surface of the powder bed. The powder can be removed by briefly turning the handle over. Next, wipe the edge of the powder bowl and wipe off the coffee powder. As a final step, gently buckle the handle to the espresso machine and be careful not to let the powder pile shake and break the closure between the coffee powder and the powder bowl.

In order to prevent the handle from being removed from the head for too long and losing too much heat, baristas need to complete these steps quickly and carefully.

↑ holds the handle of the pink hammer comfortably in the palm of your hand, making it an extension of your arm.

The ↑ wrist is vertical and gently pressed to relieve muscle pressure.

The surface of the powder bed made by ↑ powder pressing should be smooth and smooth.

Powder hammer

The powder hammer and bowl should be tightly fastened. If the powder hammer is too small, there is no way to press the surrounding area of the powder bed, and it is easy to have a channel around the powder bed. Ideally, the powder hammer should be fastened to the extent that it will get stuck in the powder bowl as long as it is slightly distorted. The author has customized many different sizes of pink hammers for his own powder bowls, and it has been found that the ideal gap between the powder hammers and the powder bowls is 51000 inches (0.127 mm). The larger the gap, the higher the probability of a channel in continuous production.

To customize the powder hammer, you can find a local machinery factory, or support a custom size powder hammer manufacturer.

Tips:

Although most commercial powder hammers are precision made, the individual sizes of powder bowls can vary greatly. The author recently bought a batch of three noodle bowls from a supplier with a diameter error of 75 mm 1000 inches (2 inch)! I found it easy to find a double bowl of the same size and a pink hammer of exactly the same size, but three bowls were not so lucky. My strategy for three noodle bowls is to order dozens of noodle bowls at once, measure those with a diameter error of less than 1, 000 inches (0.0025 mm), and then return all those with a particularly large or small error. Generally speaking, the diameter error of most powder bowls is between 2x1000 inches and 3canned 1000 inches, which is within the range that can be left behind. But I still have a pink hammer that is 10 pounds 1, 000 inches (0.254 mm) smaller than the minimum diameter.

Please note: a 58 mm powder hammer designed for a single or double powder bowl does not necessarily match every powder bowl and cannot be used on a three-part powder bowl.

Water temperature

The temperature of cooking water is very important, it will affect the flavor, concentration and flow speed. The "perfect" brewing temperature is determined by many variables, including the coffee you choose and the speed of the flow, but the most important variable is your taste. Most experts choose the water temperature in the range of 185-204 degrees Fahrenheit (about 85-95.6 degrees Celsius).

Here are several fait accompli about the correlation between water temperature and the quality of Espresso:

If the water temperature is too low, the acid and insufficient Espresso will be extracted.

Too high water temperature will extract bitter, astringent, woody flavor.

Higher water temperature will increase the extraction rate and Body of solid matter.

Higher water temperature will slow down the flow of water.

Set the cooking temperature

Before producing each cup of coffee, baristas should rinse the head with water to remove coffee fragments left on the water distribution network, and then set the temperature of the brewing water. Water discharge can be carried out when the handle is removed or an empty handle is installed.

Some machines are designed to cool the head, some to preheat the pipes and heads, and some to purify the heat exchanger. The design of each machine is different, the water discharge process is also different, and the expected boiling water temperature setting, constant pressure setting, and other settings are not the same.

The ↑ releases water without installing the handle. You can also install an empty handle to release water while preheating the handle.

Temperature Control of Multi-boiler Coffee Machine

On a multi-boiler coffee machine, one of the boilers is used to produce steam, and the other (or more) adjustable temperature boilers are used to burn water for cooking. Properly designed and equipped with a PID (proportionalintegral derivative) controller, a multi-boiler coffee machine can provide a highly consistent brewing water temperature for each product.

Such machines usually only need to release water for a short time to achieve the expected boiling water temperature, and the water temperature after discharge should be measured using a Scace temperature measuring handle or other probe thermometer.

↑ Scace temperature measuring handle and Fluke thermometer

The temperature curve of a temperature-controlled coffee machine is "flat" and looks like an L letter that turns 90 degrees clockwise. To make the water reach the set temperature, depending on the machine, it takes less than 1 second for the fast one and a few seconds for the slow one.

Temperature Control of Heat Exchange Coffee Machine

On a heat exchange coffee machine, cold water is instantly heated as it passes through the heat exchanger (a small pipe in the boiler) to the cooking head. Most heat exchange coffee machines have a circulating heat convection device that allows water to circulate between the heat exchanger and the brewing head. This device can maintain the heat of the boiling head while keeping the temperature of the water lower than the temperature stored in the heat exchanger.

The heat exchange coffee machine cannot keep the temperature of the water used for cooking at room temperature or steady. On the other hand, as shown in the figure above, the temperature suddenly rises sharply in the first few seconds, reaches its peak, stabilizes, and then begins to decline. When I say that the temperature difference between different products of a heat exchange coffee machine is less than 1 degree Fahrenheit, I mean that if the temperature curves of several products are drawn and recorded on the same chart, the temperature difference of each curve is less than 1 degree Fahrenheit.

There are three steps to control the temperature on a heat exchange coffee machine:

Step 1: adjust the constant voltage. The constant pressure can control the pressure of the boiler and then the temperature. The higher the pressure, the higher the temperature. In order to prevent the temperature of the cooking water from overheating (relative to the expected temperature), the pressure should be set appropriately low, but not so low as to affect the use of steam milk sticks. If you choose a very low boiler pressure, please note that you may want to replace the nozzle of the steam bar with a smaller diameter to ensure that the steam is fast enough to produce high-quality foam.

The allowable error of most constant pressure allows the boiler pressure to fluctuate by about 0.2 atmospheric pressure, corresponding to a temperature fluctuation of about 4 degrees Fahrenheit (2.2 degrees Celsius). The higher the stability of the temperature in the boiler, the smaller the error caused by the constant pressure. If the constant voltage can be replaced, it is recommended to install a more sensitive constant voltage, or install a PID thermostat (see the discussion of PID later in this chapter for details).

Step 2: adjust the current limiting valve of the thermal convection device (if any). The current limiting valve of the thermal convection device can improve the consistency of water temperature under continuous output and reduce the amount of cold water needed for water discharge. When the constant pressure is properly matched with the current limiting valve, the barista only needs to release a small amount of water to steadily reach a reasonable range of cooking temperature. And the temperature changes less than 1 degree Fahrenheit (about 0.56 degrees Celsius) between different products.

Please note: the current limiting valves of some machines can be adjusted, and some machines can only interfere with the boiling water temperature by replacing other sizes of current limiting valves.

Step 3: temperature surfing. When using a heat-exchange coffee machine without a throttle valve, baristas need to make more efforts to achieve barely qualified temperature stability. Such a coffee machine requires baristas to adjust the length of water according to each product, a technique called "temperature surfing".

The first step in temperature surfing is to keep releasing water until the state of the effluent changes from a quiet current to a jet (boiling), and then let the water flow for a few seconds. When the injection is finished, it means that the water in the heat exchanger has been completely discharged. To a certain extent, the longer the water is released, the greater the cooling range is. Therefore, in order to achieve the expected boiling water temperature, baristas should consider not only the length of time to release the water, but also the duration of interruption before the release of the product.

In order to ensure the efficiency of operating cafes, the process of releasing water must take as little time as possible. There is a method called "boiling immediately after putting water". The process is to release water to reach the expected temperature of boiling water, immediately buckle the handle and turn on the pressure pump. On the other hand, family baristas do not have to think about convenience, and can have more opportunities to experiment with the different effects of different release time and interruption time.

This is beneficial to accurately measure the water temperature after discharge at different times, and then choose the most suitable one. The easiest way to practice this step is to use the Scace temperature measuring handle. Other probe thermometers can also be achieved, but each measurement requires the use of new coffee powder to create real flow resistance in order to measure the accurate temperature, which makes temperature measurement a troublesome and costly task.

Temperature curve: sharp or straight

Many coffee experts spend a lot of energy discussing the pros and cons of sharp and straight temperature curves. There is almost no dispute that the two temperature curves ultimately reflect slightly different flavors in the cup. However, for any machine, the temperature of the powder bed from top to bottom during extraction is different, especially at the beginning of the extraction stage. That's because coffee powder absorbs the heat of the water when the brewing water flows down the powder bed. This fact proves that it is wrong for many baristas to crave a flat temperature curve.

The reason why many baristas prefer a straight temperature curve is that it is easy to understand and easy to reproduce. Sharp curves are difficult to reproduce in different products or different machines, but at least the curves of each high-quality product are similar.

Tips:

If you are super tech and have a lot of money, you can buy a Scace thermometer, an electronic thermometer, and a data acquisition software so you can record the temperature curve of your coffee maker. If you want to learn this knowledge, you can refer to a large number of discussions on http://www.home-barista.com, enter the "forum" and search for "datalogger scace fluke".

Adaptive proportional integral differential (PID) controller

Recently, the PID controller has been installed on the espresso machine to precisely control the temperature of the brewing water. The PID controller realizes the function by slightly adjusting the switching period of the heating element (note that the 9:PID controller controls the heat output of the heating element through a feedback loop, which includes "error value" (the difference between the actual boiler temperature and the set temperature), temperature setting value, boiler temperature and so on. PID calculates the output heat based on three elements: P (proportional, proportional term), I (integral, integral), and D (derivative, derivative). The magnitude of the error value calculated by the proportional term, the duration of the error in the integral calculation, and the rate of change of the error in the derivative calculation.

The PID on the multi-boiler coffee directly acts as a precision thermostat in the water boiler, which can accurately control the boiling water temperature within more than a tenth of a degree error. If you are already willing to spend $6000 to $10000 on a multi-boiler espresso machine, I suggest you spend a few hundred more dollars on a model with PID, the temperature stability will be greatly improved.

The PID on the heat exchange coffee machine makes the efficiency of the heat exchanger more stable by maintaining the stability of the boiler temperature, thus indirectly controlling the water temperature. To put it bluntly, installing PID on a heat exchange coffee machine is a waste of money, because a reliable and accurate constant voltage can improve the temperature stability to a considerable level and cost much less. But in any case, PID can provide real-time reading of boiler temperature, and can quickly and easily change the temperature setting, regardless of other factors.

Effluent temperature and extraction temperature

The temperature of the water used for brewing after passing through the water distribution network (outlet temperature) is completely different from that of the water actually involved in the extraction of coffee powder (extraction temperature). Many baristas are obsessed with the effluent temperature, but ignore the extraction temperature, but do not realize that the extraction temperature is the key to determine the flavor of a cup of Espresso.

Why are the two different? Because at the beginning of the extraction, the coffee powder, the powder bowl and the handle all absorb the heat of the water, making the extraction temperature lower than the effluent temperature. When the extraction is carried out until the powder bed has been fully heated, the extraction temperature is increased, and when the amount of water flowing through the coffee powder is sufficient, it can even approach the effluent temperature.

The main factors affecting the extraction temperature include:

1. Effluent temperature. One of the most influential factors is about the maximum limit of extraction temperature.

two。 The weight and temperature of the handle. A cold handle will sharply lower the extraction temperature. To maintain the handle temperature, it is necessary to shorten the time it takes to fill and press the powder after the handle is removed from the cooking head.

3. The temperature of the coffee powder. This factor does not change much during continuous production, because most cafes store coffee beans at room temperature, and the coffee powder ground by most bean grinders is basically only slightly higher than room temperature.

4. The weight of coffee powder (amount of powder). The heavier the coffee powder is, the more heat is absorbed from the water and the lower the extraction temperature at the beginning of the extraction.

5. The weight of water. The more water flows through the same weight of coffee powder, the higher the average extraction temperature.

The difference of Espresso production Technology between Italy and the United States

In the past two decades, Italian baristas have not pioneered any new Espresso production technology. On the contrary, many Espresso cultures have deviated from traditional Italian theories. In this section, the author will focus on the different powder quantity standards and water temperature standards in Italy and the United States.

Powder quantity standard

The standard amount of powder in Italy is about 6.5g for single part (1-oz / 30-ml) and 13g for double part (2-oz / 60-ml). In the past, using such standard parameters, with pre-ground coffee powder and standard single or double powder bowls, it was possible to make Espresso with acceptable brewing ratio and concentration.

Recently, many American baristas like to use larger amounts of powder, often more than 20 grams at a time. In the case of more and more radical baristas, the standard amount of powder per serving has evolved from 7 grams of Italian standard to 14 grams of double Ristretto, then to more than 14 grams of double Ristretto, and finally to triple Ristretto. None of these products are Ristretto in the traditional sense (the authentic practice is to reduce the cup volume in a single serving of powder), only the cup volume maintains the standard value (30-15 ml), while the powder quantity exceeds (or even far exceeds) the standard value. These new powder standards are not universal, but they have one thing in common: many respected cafes are in use. The revolution about the amount of powder is designed to cater to two directions: one is that more Americans like to use the amount of powder, and the other is the popularity of grinding on demand.

Summary

So far, we have explained the details of making Espresso separately. Now let's put all the parts together and describe the process of producing an Espresso. Please note: this is just a sample process and you may need to adjust the order of tasks slightly for some special devices. For example, if your bean grinder is slow, adjust the grinding to the first step:

1. Remove the handle.

two。 If your machine takes a long time to release water, start releasing water immediately. And stop releasing water at the appropriate time.

3. Knock out the used pressed powder.

4. Wipe the powder bowl on the handle to make sure that each filter hole of the powder bowl is unblocked.

5. Turn on the bean grinder (if your bean mill is slow, adjust this step to the first step).

6. Start filling powder. When filling the powder, draw a circle with the handle and let the coffee powder fill the whole bowl evenly.

7. After getting the right amount of coffee powder, turn off the bean grinder.

8. Powder filling is complete.

9. Trim and fill the powder.

10. Make sure the powder hammer is dry and there is no coffee powder left.

11. Press the powder gently.

twelve。 Wipe off the loose coffee powder on the edge of the powder bowl.

13. If the time required for your machine to release water is very short, you can start releasing water at this step.

14. Buckle the handle and turn on the pressure pump.

15. Observe the bottom of the bottomless handle, if the channel effect is found, find out the most likely cause, record it, and start step 1 again.

16. Disrupt the flow according to the expected Espresso fluid volume or effluent color.

17. Taste the product immediately.

18. If the flow rate is faster or slower than expected, consider adjusting the degree of grinding.

How to observe the quality of the product

Baristas can't tell the taste of the Espresso just by looking at the extract. But when baristas know a lot about a particular coffee machine and a particular coffee bean, they can judge whether a product is good or bad from visual clues.

The following guidelines are just a framework to help you visually judge the quality of the product, and you need to adjust your judgment of flow rate and liquid color changes according to the coffee machine and beans you use. All the observations mentioned below are based on the use of bottomless handles.

If there is a pre-immersion, the coffee liquid will flow out from the bottom of the powder bowl 3 seconds after starting the pressure pump. In the case of no pre-immersion, the liquid will be released after 2-5 seconds. Either way, we set the time at which the coffee liquid starts to flow out to 0 seconds.

Within the first 2 seconds, the dark brown liquid will flow out from the bottom of the powder bowl. If in these 2 seconds the coffee liquid does not flow from all areas at the bottom of the bowl, but only from a local area, it proves that the extraction is uneven.

At the stage of 3-5 seconds, you will see the sticky brown Espresso liquid coming out of the powder bowl. At this stage, as long as you see a little yellow, it means that the channel has been formed, the reason is that the grinding degree is too rough, or the extraction temperature is inappropriate.

During the 8-12-second period, the liquid will be mixed with some brown / orange water.

In the rest of the time, the color of the effluent will become more and more yellow. According to the expected Espresso extraction rate and flavor, the whole extraction process should be completed within 20-35 seconds.

Water temperature difference between Italy and the United States

I often wonder why so many Italian baristas use 185-195 degrees Fahrenheit as the standard range for effluent temperature, while many American baristas, especially those who are very aggressive, use a temperature range of 1988,204 degrees Fahrenheit (92.2-95.6 degrees Celsius). I think part of the reason is that most Italian baristas use 7 grams of powder to extract 30ml cups, while Americans use 18 grams of 21 grams of powder to extract 30ml cups. Therefore, although there are differences in the effluent temperature, the two methods are ultimately similar in the average extraction temperature.

Why is this happening? This is because Americans use more powder, so coffee powder takes away more temperature from the brewing water.

To prove this, let's do an interesting thought experiment: suppose you put the product into the preheated coffee cup A with 7 grams of 80 degrees Fahrenheit coffee powder and 30 grams of 190.5 degrees Fahrenheit water. The temperature of the coffee liquid should be 181.1 degrees Fahrenheit. We use 21 grams of 80 degrees Fahrenheit coffee powder and 38 grams of 203.5 degrees Fahrenheit water to connect the coffee cup B with the same temperature as coffee cup A, and the temperature of the coffee liquid should also be 181.1 degrees Fahrenheit. So we can boldly guess that each gram of coffee powder can absorb one gram of water.

The data for this thought experiment can be presented more clearly in the following table:

↑, how are these values calculated:

Coffee cup av 181.1 = (30 x 190.5 + (7 x 80 x 0.4))-(30 + (7 x 0.4))

Coffee cup BRV 181.1 = (38 x 203.5 + (21 x 80 x 0.4)-(38 + (21 x 0.4))

I would like to thank Andy Schecter for guiding the author on the concept of specific heat capacity and for processing the above data to make the data accurate.

Make high quality straight out Espresso and milk coffee.

Making a high-quality straight-out Espresso is not the same thing as making a high-quality 12-oz latte. When going straight out of Espresso, the concentration should be reduced to enhance the potential flavor of the selected mixed beans. Too low concentration will lead to insufficient Body, because the concentration and Body are closely related; too high concentration will interfere with drinkers to capture the subtle flavor in Espresso.

To make a perfect 12-oz latte, you need Espresso to reach enough quantity and concentration to counteract large amounts of milk. The flavor of the product is also important at this time, but it is not as important as when you go straight out of the Espresso, because in the latte, the subtle flavor of Espresso is masked by milk.

In order to meet the demand for both Espresso and milk coffee, there are many excellent cafes in the United States that choose a large amount of powder to cope with all products. This can make a good Espresso and latte, but it is very expensive, the profiteering rate is also very high, and there is no targeted optimization for lattes and Espresso straight out.

The author recommends two ways for cafes to tailor clothes for different production purposes.

Use two bean grinders: the easiest way to make two different Espresso is to use different coffee beans and bean grinders. Furthermore, one of the brewing heads of the espresso machine can be used separately to go straight out of the Espresso to set the appropriate water temperature for the selected coffee beans.

Use different sizes of powder bowls, different filling and dressing techniques: if the barista uses the traditional Italian 7g powder and double 14g powder, the concentration, flavor and flow rate of the final product will be roughly the same. But if the barista uses his fingers to trim the powder, there will be less powder in the powder bowl than the standard powder (Note 10). This will lead to changes in flow rate (faster), concentration, and flavor.

The solution is to use two or three different sizes of powder bowls, and use different powder filling and dressing techniques for each powder bowl. For example, the author has a bean grinder, a single flour bowl, and a double powder bowl at home. I am used to using a single bowl to make Espresso; with moderate concentration, round taste and high sweetness. Double Ristretto with higher concentration and richer Body produced by double bowl is used to make cappuccino. If a double bowl is trimmed with a straight ruler tool, or a single bowl is trimmed with the round lid of a bean grinder, both bowls will extract 30 ml coffee with a similar weight and flow rate. Moreover, each product can meet the expected powder-to-water ratio, flavor and concentration.

Tips: my evolutionary path of powder filling (visiting two continents to learn how to fill powder)

When I first went to Italy, I was in my eighth year as a barista and was used to producing 30 ml~45 ml Espresso with three times the amount of powder (20 grams). Most of the Espresso I drink in Italy is sweeter, less acidic, lighter and Body thinner than the one I made myself. When I got back, I tried to adjust my Espresso to imitate the flavor I had in Italy, but I never did.

A few years later, I came to work at the Mojo Cafe in Wellington, New Zealand. Mojo uses the Italian powder standard and chooses blended beans with a shallow baking degree (before the second explosion) and is mainly composed of acid-washed beans. I thought the Espresso would be super bright and super sour, but on the contrary, it has delightful sweetness and moderate acidity. Obviously, the difference in the amount of powder makes the flavor more or less round and sweet. To test this idea, I tried to produce a double Ristretto with an overloaded double powder bowl (there are no three powder bowls in the store, and that's the closest I can use to the powder made in my previous cafe), which is significantly more exciting and less sweet than the Espresso made with the amount of powder and brewing ratio of Mojo.

When I went back to the United States to open my second coffee shop, I used back 20 grams of powder. I wish my Espresso tasted closer to the ones I made in New Zealand, but I struggled: I couldn't make a satisfactory 12-oz (360 ml) and 16-oz (480 ml) lattes with less powder, because the flavor of Espresso would be masked by milk. Given that direct Espresso sales account for less than 5% of total espresso sales, it's hard to sacrifice 95% of customers in order to make straight out Espresso taste better. (please suppress your anger and finish this chapter.)

Pressure interference in the process of Espresso extraction

After the start of production, there are several things that may temporarily reduce the extraction pressure (except the drawbar machine).

1. Wash or drain the other head

two。 Produce with another cooking head.

3. The automatic intake valve of the boiler starts to work.

4. Other machines are pouring in water, reducing the pipe pressure of the espresso machine.

These stress variables can lead to the generation of channels, which should be avoided by using the following simple strategies as much as possible.

1. When there is a cooking head in production, do not wash other cooking heads.

two。 If you want to make two products at the same time, you should clean both heads at the same time, fill both handles, and press the product button at the same time (Note 10: busy baristas will find that strategy 1 and strategy 2 cannot be implemented without affecting the speed of service. In other words, any barista can only use these strategies as much as possible.

3. Check the water pipe connection of the coffee machine to prevent the automatic water intake valve of the boiler from opening when the pressure pump starts.

4. If other machines (drip filters, dishwashers, etc.) compete with espresso machines for water pressure, you can protect them by following these steps. From the upstream to the downstream of the water pipe, the water treatment system, balloon pressure tank, pressure reducer and Italian coffee machine are installed sequentially. The water treatment system is put first because the pressure fluctuates with the fluctuation of the water treatment system. The pressure fluctuation will then be absorbed by the airbag, and then released by the airbag stable and high-pressure downstream water pressure, not affected by the upstream pressure (within a reasonable range). Next, the high pressure released from the airbag is reduced by the pressure reducer to the expected input pressure of the espresso machine. The airbag and the pressure reducer add up to about $200.

(chapter 2 ends)

Chapter III, to be continued.