Practical information | Translation of the Handbook of Professional baristas (3) the strength of pressing powder, how to press powder..

Professional barista communication, please pay attention to coffee workshop (Weixin Official Accounts cafe_style )

There are many people who admire the profession of barista, and some even aspire to become one. These ideas are not surprising, as baristas can indeed taste all the best coffee, and they can also experiment with cool drinks and use those ultra-expensive coffee machines.

Making coffee is not as simple as it seems.

First of all, to become a barista, you must have sufficient knowledge about coffee. Some people think that most baristas don't need much training to get started. But in fact, every barista is systematically trained to understand every aspect of coffee shop operations, from table service to cup washing.

The most important ability a barista needs is the ability to multitask. The barista must ensure that the milk foam is just right and the water output of the coffee machine is accurate while constantly receiving orders. A good barista also has to be able to handle the special requests of special customers while maintaining a smile at all times.

Professional Barista Handbook

Translated by Scott Rao

How do professional baristas get started? The Professional Barista Handbook (1)

dry goods| Espresso Grinding, Filling and Powdering

Continue to chapter 2...

pressed powder

Pressing powder locks the cloth powder, smoothes the surface of the powder bed, and eliminates pores in the powder bed. Powder pressing also allows baristas to feel the quality of filling, powder distribution and grinding.

The intensity of the powder pressing

Contrary to the general opinion, the author thinks that the impact of powder pressing force on velocity is very small. Once sufficient pressure has been applied, the pores in the powder bed have been eliminated, and additional pressure does 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 interesting reason is that when using the same amount of powder and the same powder bowl, heavy powder will make the powder bed more compact and make the "separation space" between coffee powder and water distribution net larger.) Since water must fill this space before it can be pressurized through the coffee grounds, the larger space can extend the time between the start of the pressure pump and the start of extraction. An extension of this time may lead baristas to overestimate the impact of heavy powder on flow rate). The following two points can be proved:

1. All (or part) of the pressure generated by the pressing is released after the coffee powder has been wetted.

2. The 50 pounds or so of pressure exerted by the barista when pressing the powder pales in comparison to the 500 pounds or so exerted by the coffee machine pressure pump during extraction (Note 7:9 atmospheres ≈130.5 psi (pounds per square inch); the surface area of coffee powder in a 58mm powder bowl is 4.09 square inches;130.5 × 4.09 = 533.7 pounds).

It's hard to say what's good about pressing powder with a lot of force, but pressing powder with less force has at least two advantages: less pressure on the barista's wrist and shoulders, and it's easier to make perfectly horizontal presses (especially when using a high-fit powder hammer and bowl). If the barista uses a lot of force to press the powder, the chances of the powder hammer and powder bowl sticking will increase greatly, indicating that the powder hammer is not horizontal).

Knock or no knock?

A recent debate about powder pressing has focused on whether to tap the handle while pressing powder. The main knock school believes that beating can knock off loose coffee powder squeezed onto the edge of the powder bowl during the first press, and then press this coffee powder into the powder bed through the second press.

You need to weigh the benefits of pressing that powder back into the bed against the potential harm of knocking. The tapping action breaks the seal between the coffee powder and the bowl wall, creating a channel around the powder bed. In my experience, such a channel is basically impossible to close through the second powder pressing. Of course, it may not break the closure every time you hit it, but it's still not worth the risk. In short: a little powder, if a problem, 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.

One barista I admire uses her wrist to tap (like a champagne hammer) in order to harmonize the powder bed. If you have to, it seems safer than tapping with the hard handle of a powder hammer.

How to press powder

Gently hold the hammer in your hand and adjust the handle of the hammer until it seems to be an extension of your arm. Straighten your wrist so that the bottom of the hammer handle rests comfortably in the palm of your hand. This position minimizes stress on the wrist, which is great for baristas who do hundreds of powder presses a week.

Keeping the hammer level, gently squeeze it onto the pile. Then it's enough, no need to twist or press again.

After lifting the hammer, there may still 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 simply turning the handle over. Next, wipe the rim of the powder bowl and wipe the coffee powder clean. As a final step, gently snap the handle onto the espresso maker, taking care not to let the powder pile shake and break the closure between the coffee powder and the powder bowl.

To avoid taking too long to remove the handle from the brewing head and losing too much heat, the barista needs to complete these steps quickly and carefully.

↑ Hold the handle of the hammer comfortably in the palm of your hand so that it becomes an extension of your arm.

↑ Wrist vertical, gently fill pressure, reduce muscle pressure.

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

powder hammer

The hammer and bowl should fit together tightly. If the powder hammer is too small, there is no way to compact the surrounding area of the powder bed, and it is easy to appear around the powder bed channel. Ideally, the hammer should snap together so that it will get stuck in the bowl if it is slightly distorted. The author customizes a number of different size of hammers for his bowls and has found that the ideal gap between the hammer and bowl is 5/1000 of an inch (0.127 mm). The larger the gap, the higher the chance of a channel appearing in a row.

To customize the hammer, find your local machine shop or hammer manufacturer that supports custom size.

Tips：

Although most commercial hammers are precision manufactured, individual size of the bowl can vary widely. A recent batch of three powder bowls purchased by the author from a supplier had a diameter error of 75/1000 inches (2 mm)! I found it easy to find double bowls of the same size and hammers of the right size, but not so lucky with triple bowls. My strategy for three powder bowls is to order dozens at a time, measure the diameter to within 1/1000th of an inch (0.0025 mm), and return all the extra large or small ones. Generally speaking, most powder bowls will have a diameter error of 2/1000 inch to 3/1000 inch, which is the range that can be left behind. But I do have a powder hammer that is 10/1000 inches (0.254 mm) smaller than the minimum diameter.

Please note that a 58 mm hammer designed for single or double serving bowls does not necessarily match each bowl equally and cannot be used on triple serving bowls.

water temperature

Brewing water temperature is very important, it will affect flavor, concentration and water flow rate. The "perfect" brew temperature depends on many variables, including the coffee you choose, the speed of the water flow, but the most important variable is your taste. Most experts choose temperatures in the range of 185 to 204 degrees Fahrenheit.

Here are a few facts about the correlation between water temperature and espresso quality:

·Too low water temperatures will extract acid and under-extracted Espresso.

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

·Higher water temperatures result in higher solids extraction rates and higher Body.

·Higher water temperatures slow water flow.

Set brewing temperature

Before serving each cup of coffee, the barista should rinse the brew head with water to remove coffee debris from the water trap and set the brew temperature. Water discharge can be performed with the handle removed or with the empty handle installed.

Some machines are designed to cool the brew head, some to preheat the pipes and brew head, and some to purify the heat exchanger. Each machine has a different design, different draining procedures, and different settings for the desired brewing water temperature, constant pressure, and other settings.

↑ Drain water without handle installed. Empty handles can also be installed to drain water and preheat the handles at the same time.

Temperature control of multi-boiler coffee machine

In a multi-boiler coffee machine design, one boiler is used to produce steam and another (or more) temperature-adjustable boiler is used to boil brewing water. When properly designed and equipped with PID (proportional integral derivative) controllers, a multi-boiler coffee maker can provide a highly consistent brew temperature for each serving.

Such machines usually require only a short time to drain to reach the desired brew temperature, which should be measured using a Scace thermometer handle or other bead-type thermometer.

↑ Scace temperature measuring handle and Fluke thermometer

The temperature-controlled coffee machine produces a "flat" temperature curve that looks like an L rotated 90 degrees clockwise. To bring the brewing water to the set temperature, depending on the machine, it takes less than 1 second for the fast and a few seconds for the slow.

Temperature control of heat exchanger coffee machine

On heat exchanger coffee machines, cold water is heated instantaneously as it passes through a heat exchanger (a small pipe in the boiler) to the brewing head. Most heat exchanger coffee machines have a circulating thermal convection device that circulates water between the heat exchanger and the brewing head. This device maintains the heat of the brewing head while keeping the water cooler than it is stored in the heat exchanger.

Heat exchanger coffee machines do not keep the temperature of the brewing water at room temperature or even. In contrast, as shown in the graph above, the temperature rises sharply in the first few seconds, peaks, stabilizes, and then begins to decline. When I say that the difference in temperature between different products of the heat exchanger coffee machine is within 1 degree Fahrenheit, I mean that if several temperature curves are plotted on the same chart, each curve is within 1 degree Fahrenheit.)

Controlling the temperature on a heat exchanger coffee machine requires three steps:

Step 1: Adjust the constant voltage. The pressure-constant can control the pressure of the boiler and thus the temperature. The higher the pressure, the higher the temperature. To prevent overheating of the brewing water (relative to the expected temperature), the pressure should be set low enough, but not so low as to interfere with the use of the steam milk stick. If you choose a very low boiler pressure, note that you may want to replace the steam wand nozzle with a smaller bore to ensure that the steam velocity is sufficient to produce good foam.

Most pressure-stat tolerances allow for fluctuations of about 0.2 atmospheres in boiler pressure, corresponding to fluctuations of about 4 degrees Fahrenheit (2.2 degrees Celsius) in temperature. The higher the stability of temperature in boiler, the smaller the error caused by 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 discussion of PID later in this chapter).

Step 2: Adjust the throttle valve (if any) of the thermal convection device. The thermal convection device's restrictor valve can improve the consistency of water temperature under continuous production and reduce the amount of cold water required for water discharge. With the right combination of a constant pressure and a restrictor valve, the barista needs to drain only a small amount of water to reach a reasonable brewing temperature range stably. And the temperature varies by less than 1 degree Fahrenheit (about 0.56 degrees Celsius) between different products.

Please note: some machines have adjustable flow restriction valves, some machines can only intervene in the brewing water temperature by replacing flow restriction valves of other size.

Step 3: Temperature Surfing. When using a heat exchanger coffee machine without a throttle valve, the barista has to work harder to get the temperature to a barely acceptable level of stability. Such coffee machines require the barista to adjust the length of the water according to each product, a technique called "temperature surfing."

The first step in temperature surfing is to keep running water until the water changes from a quiet stream to a jet (boiling) and then let the stream flow for a few seconds. When the injection is over, it means that the water in the heat exchanger has been completely discharged. To a certain extent, the longer the drainage time, the greater the cooling range. Therefore, in order to achieve the desired brewing temperature, the barista should consider both the length of water and the length of time between the release of water and the production.

In order to keep the cafe open efficiently, the time spent on this process must be as short as possible. There is a method called "boiling after putting water". The process is: after pouring water to reach the expected boiling temperature, immediately buckle the handle and turn on the pressure pump. Home baristas, on the other hand, don't have to worry about convenience and have more opportunities to experiment with the different effects of different water release times and interruption times.

This helps to accurately measure the water temperature after water discharge at different times, and then choose the most suitable one. The easiest way to do this is to use the Scace temperature measuring handle. Other bead-type thermometers can be used, but each measurement requires the use of new coffee powder to create a true resistance to water flow in order to measure accurate temperatures, which makes temperature measurement a troublesome and expensive business.

Temperature curve: sharp or straight

Many coffee experts spend a lot of time debating the pros and cons of sharp versus flat temperature curves. There is little dispute that the two temperature curves end up with slightly different flavors in the cup. However, for any machine, there is a difference in the temperature of the powder bed from top to bottom during extraction, especially at the beginning of extraction. That's because coffee grounds absorb heat from brewing water as it flows down the bed. This fact proves that many baristas are wrong about their obsession with flat temperature curves.

Many baristas prefer flat temperature curves because they are easy to understand and reproduce. Sharp curves are difficult to reproduce in different products or different machines, but at least every good product has similar curves.

Tips：

If you're super techie and rich, buy a Scace thermometer handle, an electronic thermometer, and data acquisition software so you can record the temperature profile of your coffee maker. To learn more about this, go to http://www.home-barista.com and search for datalogger scace fluke.

Adaptive 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.