Boutique Coffee about Espresso Coffee

ESPRESSO COFFEE: Professional Techniques-

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The first part of the basic concepts

Build a knowledge architecture-

Just a bunch of facts, just a bunch of facts. Theory is the skeleton of fact. The experience of teaching others to cook espresso taught me one thing: if I told newcomers about the basic theory of espresso at the beginning, it would be easier for them to cook a good espresso after the course. Because in order to cook a good espresso, you have to face complicated practical problems. With a proper theoretical basis, their ability to understand problems can be enhanced.

Why is it so hard to cook espresso?

The problems with making a great espresso are mostly due to two factors: "uneven flow of water" and "the aroma of coffee is very volatile".

The problem of the current-

Modern espresso machines can produce water pressure of 120 to 130 pounds, while coffee cakes are less than half an inch thick. The big problem with espresso comes from espresso's feature: using pressurized hot water to pass through a thin coffee cake.

Water has a property-

He will always find the shortcut with the least resistance in the coffee powder, instead of trying to extract the soluble coffee oil. So a large part of this book is about how to make coffee powder evenly resistant to high-pressure water.

As long as the coffee filter cake has a little uneven density or the surface collapses, the high-pressure water will rush up and break through your "cover door". In the coffee filter cake, the low density part will be over-extracted after the delicious ingredients flow out. On the other hand, the parts with higher density are not extracted enough.

When this espresso flows out, the water flows in a spiral shape. The surface tension is relatively high and it is tightly attached to the outlet. In addition to the delicious reddish-brown liquid, there are white lines and small cups of coffee.

To make matters worse, it happens when the beans are ground too thick or the resistance of the filter cake is uneven. As soon as the high-pressure water is leaking, the light brown liquid is pouring down.

It looks like a toilet in color and taste.

To cook a perfect espresso- like this

Grind the correct amount of coffee powder, carefully flatten it and disperse it, and then rotate and grind it out after being evenly compacted with a filler. After being done, there should be some gaps between the surface of the coffee filter cake and the shunt net of the machine outlet. Turn on the pump switch and the water will flow down and wet the coffee powder for about a second before the pump is actually started. This is called "prepreg", which helps seal the surface of the filter cake (Italian engineers are well aware of the benefits of "prepreg"), and the delicious ingredients in the powder do not stick so tightly when they come into contact with hot water. It's easier to extract when high-pressure water comes over.

Because the cooking temperature is as high as 200 degrees Fahrenheit and the pressure is as high as 120 pounds. If the resistance of the filter cake is uneven, it will rush out of the hole or pore diameter, resulting in uneven extraction. The part of insufficient extraction will cause the yellowish-brown liquid of water in the outlet head, and the part of over-extraction will dissolve other substances and cause white stripes.

In fact, what is said above is just an idealized overview. There are many factors that seriously affect the ability of coffee powder to withstand water pressure, such as: filling, dosage, freshness of beans, thickness of grinding, blade form of bean grinder, and air humidity. Only by controlling these many factors and understanding their relationship with each other can the matter be resolved.

When all is done, for the next 25 seconds, you can see high-pressure water squeeze through the coffee powder and inject a perfect cup of espresso.

ESPRESSO COFFEE: Professional Techniques-

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Chapter II Espresso principle

The aroma components dissipate easily-

The rich aroma of grinding fresh coffee has inspired the poet for hundreds of years. In order to capture these aromas in coffee cups, all kinds of beautiful shapes and strange coffee machines have come out one after another, thus achieving this arduous "super task".

Why is it so difficult to make brewed coffee as fragrant as freshly ground coffee? That's because the aroma of coffee comes from coffee sesame oil, which is unstable and volatile. As soon as it comes into contact with air, it will oxidize and give off a rotten smell. The boiled water is so hot that it will burn out. The temperature of the boiling water is too low and it becomes sour. Therefore, how to brew coffee without destroying the coffee oil is really a big problem!

No matter which method is used to make coffee, the freshness of beans is "supreme program". This is especially true when cooking espresso. Because espresso cooking will enhance the properties of coffee, if the oil damage becomes bitter, the coffee will taste more bitter. What's more, baked beans themselves contain a variety of compounds and acids that can destroy oils.

The key to playing espresso is to separate fragrant oils from substances that are harmful to delicacy as much as possible.

Espresso, art is also-

The beauty of espresso lies in the full understanding of the aromatic substances, but also from the beans into the coffee cup. However, with a wide variety of substances and a wide range of projects, it is impossible to rely on rigorous chemical analysis.

It takes a little intuition and a little luck to make good coffee.

The factors related to this are listed below:

1. Temperature of boiling water

two。 Cooking time

3. The amount of boiled portion

4. Freshness of coffee

5. The cleaning of the machine

6. Baking depth of beans

It should be noted that the above factors affect each other and affect the whole body. More importantly, when you explore these features one by one. Don't forget: "the water will flow unevenly" and "the fragrance will dissipate easily".

Engineers! Work hard!

Over the past few years, we have been able to effectively control the factors affecting coffee brewing through bit by bit research and improvement in our own store. At present, the most important part in need of improvement is the water temperature of the espresso machine. Sometimes, the water temperature is so accurate that we can make "coffee as delicious as the sound of nature":

Fragrant, rich, rich, smooth. After drinking, I was so happy that I knocked the cup and smashed the pot and roared up to the sky.

I personally think that coffee is greatly affected by the temperature of the brewing water. Even if the change in water temperature is as small as ±1 ℉, there is nothing I can do about it: at the outlet, there is at least a temperature change of ±4 ℉. (that is, a total of 8 ℉ changes)

In terms of temperature stability, machines with exclusive flushing boilers are better than heat exchange machines. In the seventh chapter of this book, we will teach you some ways to change the temperature a little bit.

However, we still need the assistance of professional engineers. I hereby appeal to:

All the excellent espresso engineers in the world!

Please don't stop at the amazing achievements you have made.

In order to make the water temperature of the outlet head more stable

In order to make the water temperature of the whole coffee filter more stable

Work hard!

ESPRESSO COFFEE: Professional Techniques

(Ⅲ)

Chapter III Environmental factors-- temperature, Sunshine and humidity

What is meant by "variable cause"-

In the process of cooking espresso, the factors that will affect the quality of espresso are called variants. Some variables are caused by different "human" skills, while others are not easy to control. For example, the environment of nature is always changing all the time. In the face of these uncertainties, the bar staff must maintain the mobile adjustment of cooking at any time in order to maintain the consistent quality.

God is always elusive-

I started my business in 1988, when I started as a vendor. I soon found that cooking espresso outdoors is much more affected by the weather than when cooking it indoors. If the temperature is low and the humidity is moderate (relative humidity 50-60%), the ground coffee can be placed for 4 minutes without affecting the flavor. However, it is important to note that ground coffee powder is as troublesome as the weather. The moment the beans are ground into powder, oxidation begins.

When the weather is hot, the coffee will stale faster. Ground coffee powder is faster! Whether it's the heat, the dry air, or the sun shining directly on the beans, it's espresso's nightmare. Because such an environment will cause the moisture in the beans to be quickly lost in the grinding process. The fleeing water molecules take away the aromatic ingredients in the beans, and the coffee tastes much worse.

Of course, it's impossible to cover everything, but it's helpful to pay attention to a few details:

Only grind enough coffee powder at a time, don't grind too much and save the rest for the next cup.

The lid of the bean grinder should be covered and can be sealed with electrical tape.

Coffee powder and compaction should be done quickly and accurately, so that there is no gap in the dry air.

In the shop, we found that the best way is to grind only when there are guests, and only this cup is enough.

Even if you are so careful, you can cook a great espresso on a cool October day, but it is still difficult to do the same outside in August. I'm afraid the only way to cook an espresso appreciated by experts is to hide indoors. Because the indoor environment is easier to control, the vendor style of cooking will probably be phased out. "High temperature" and "low humidity" (WebBarista: the United States is relatively dry, often you will be "electrocuted" when you open the door. I'm afraid Taiwan has to worry about the high humidity. Will deal a fatal blow to coffee.

What are we going to do?

When buying beans, buy a small amount of beans many times, about once every five days. The beans in stock should be sealed and stored in the basement, or in a cool place. (when it comes to the freshness of beans, we will discuss them in more detail.)

Outside in Seattle in August, our stall did this: we put two cups of beans at a time (used up in about 15 minutes), and when the beans were still on standby in the funnel above the bean grinder, we lined a piece of white paper inside the funnel for fear that the sun would shine directly into the beans and to keep out some heat. I cherish the beans very much.

Baby! It's very cold outside!

When the weather is very cold, it is also a challenge to make coffee outdoors. Because the filter handle cools faster, all espresso machines expose the outlet head, filter and handle. These metal parts dissipate heat easily. Although the espresso machine is designed to keep the temperature of these important parts constant. (of course, this section of the way from the liquid down to the cup should be included.) In winter, the temperature still drops by 10 degrees.

To solve the problems caused by low temperature, we need some common sense.

Lock your hand on the outlet for as long as possible to keep warm (don't hold the handle and shake it around when you fart with a customer.) All actions should be "go, go! go, go!" Grind the coffee, quickly knock the residue in the handle, and immediately fill it with fresh coffee powder. The shorter the time, the less the degree of cooling.

Preheat the handle and outlet head, grind down a cup of coffee powder and start the pump to allow hot water to flow through the handle and used coffee powder. Be careful not to use more than 2 ounces of hot water, so as not to destroy the heat balance of the machine and lower the water temperature.

"moisture" is the culprit-

The ground coffee powder has strong hygroscopicity. When the surrounding environment is relatively moderate, it will absorb moisture from it. When the surrounding environment is relatively moderate, it will release moisture. If the humidity in the environment is very heavy, the packing will be tight and the extraction rate will be reduced. Therefore, it is necessary to cook espresso at the right time.

When cooking espresso, we pay great attention to how much water passes through the coffee cake every second. Espresso's "golden law of flow rate" is: "whether it is a single or double dose, the extraction time is about 25 seconds." In this way, you can extract delicious ingredients as much as you can, while at the same time extracting the least amount of caffeine and unpalatable substances. (as long as the filter of single dose and double dose are of the same shape and depth, the best extraction time will be the same.)

To control the "25-second extraction time", the method used in my store is to keep all other variables unchanged and only adjust the grinding thickness (dose and packing pressure also remain the same to reduce variables.)

Coffee is very sensitive to moisture, and we train the bar staff to fine-tune it according to the extraction time, even when the moist air on the sea blows in.

Adjust the tone of the violin-

When cooking espresso, keep the filling weight and dosage unchanged, and only change the thickness of grinding.

When the moisture increases, the coffee will absorb moisture, the filling pressure will be relatively tight, and the resistance to water pressure is also stronger. In order to maintain the "25-second extraction time", adjust the grinding degree a little bit at this time.

When the moisture decreases, adjust the grinding degree a little bit.

Of course, we don't keep an eye on the hygrometer while making coffee. Having said so much, I just want to tell you why the extraction time of coffee is constantly changing on the same day.

You should think of yourself as a musician adjusting the timbre of the violin: adjust the body of the violin with slight changes in the temperature and humidity of the environment. It resonates beautifully.

ESPRESSO COFFEE: Professional Techniques

(Ⅳ)

Chapter IV Espresso bean grinder

When Espresso cooks something wrong, it is often difficult to find out the exact reason. That is because there are too many reasons for making good coffee and are related to each other. As long as there is a little mistake (such as the beans are not fresh, the hot water temperature is not right), a cup of espresso will be ruined! The quality of the bean grinder is one of the most important factors.

Why is the bean grinder so important-

The reason is based on the way espresso operates:

The water pressure is very high and the cooking time is very short.

Cooking time-

The so-called "brewing time" refers to the time it takes for hot water to penetrate coffee powder. Ideally, the time for high-pressure hot water to contact coffee powder is about 25 to 28 seconds. In such a short time, water-soluble aromatic substances are not allowed to dissolve slowly. It takes a long time to use trickling or French filter press, which takes 3 to 5 minutes.)

With the method of cooking for a long time, a cheap propeller bean grinder is enough. And the espresso cooking method is fast and fierce, there is no room for mistakes, the need for more accurate grinding. The position of the bean grinder is very important. after the beans are torn into powder, the tangled surface of these particles greatly increases the overall surface area, and hot water can easily evenly extract the maximum concentration of delicious coffee oil.

High pressure water-

The oil is emulsified and extracted under pressure to form a reddish-brown foam-like crema. The delicious substances contained in crema are refreshing. So what is the best pressure? It is generally believed that the pressure of cooking espresso should be between 8.2 and 9 atmospheres. I set it at 8.2 atmospheric pressure myself.

Stabilize the pump pressure-

The water pressure in our shop is very unstable, high in the morning and low in the afternoon. Sometimes there will be sudden changes, and even the dishwasher at the back will affect the espresso at the front bar when it comes to water.

Once the inlet pressure changes, so does the rotary pump of espresso. In order to solve this problem, we have installed a 3-gallon stainless steel storage tank in front of the inlet of the espresso machine, and equipped with automatic water intake device (including float switch, solenoid valve, adapter), the pressure of the inlet can be maintained at 1 atmospheric pressure.

Potential trouble-

These newly added pipeline fittings should be careful not to seep air. The pump inlet cannot be pumped empty without water. Otherwise, the espresso machine pump, which was originally used to pump water, will draw air and cannot move, and the pressure will not come up.

ESPRESSO COFFEE: Professional Techniques

(Ⅶ)

Chapter 7

The temperature of the brewed water-- the element of good coffee--

The quality of water temperature control absolutely affects whether a cup of coffee can preserve the delicious substances in the beans. The better your coffee is made, the more intractable the ultimate problem of "water temperature" becomes. The water temperature seriously affects the quality of coffee, but it is difficult to control.

The water temperature is not easy to measure, because the water temperature of the espresso machine is higher than 200 ℉ and the amount of water is small, and the action of measurement will more or less lower the water temperature. This kind of "measurement technology will affect the subject to be measured" is an old problem.

Therefore, I advise you not to measure the water temperature directly. Instead, the "try-error-correct" method is used to determine the temperature. Use your own taste buds as sensors. There is another reason for this: beans with different baking degrees have different optimal cooking temperatures.

However, I will still use "temperature" as a quantitative indicator to give you an idea. (I used the Fluke 51K hand J digital thermocouple J alloy probe. The beans were baked to a dark reddish brown of Beiyi Dali style with no oil on the surface.)

The temperature of the water is not right-

The ideal water temperature is to indicate that the temperature of the head is 203.5 ℉. The boiled espresso is very dark reddish brown, and the crema will have dark brown spots. (some Italians call it "el tigre" which means "tiger stripes".)

The temperature of the water is too low and the coffee is yellowish brown. Crema is also very thick, smooth and uniform, but the color is relatively light, there are no dark spots. If the temperature is below 195 ℉, it tastes bitter and sour. It couldn't be worse to cook my baked beans like this.

(please refer to pages 106 and 107 of the original book for comparative photos of ideal water temperature and low water temperature.)

On the other hand, the high water temperature will burn out the coffee oil, there will be a "bite the tongue" feeling, the aftertaste is anxious. In the worst case, there will be thick dark black stripes on the surface of the crema. If the water temperature is just a little high, the boiled espresso is ordinary and boring, not bad, but not wonderful.

The characteristics of the taste are determined by the beans. If cooked properly, coffee should smell the same as freshly ground coffee powder

The temperature is well controlled, and the texture is thick and smooth.

As I mentioned in Chapter 5 (Commercial espresso machines), engineers still need to work hard to control the temperature of the outlet head in order to win more applause. Many espresso machine manufacturers have all kinds of patents, but I personally think there is still a long way to go.

The effluent of the water boiler can be maintained at a variation of ±1 ℃ (equivalent to ±1.8 ℉), but it is another matter to maintain the temperature stability of the outlet head. The machines I have tried have a change of at least 6 degrees (equivalent to ±3 degrees).

The structure of the filter handle itself should also be held responsible. It itself is made of heavy metal for the purpose of heat preservation. But metal is easy to dissipate heat. Take your hand off the machine, put coffee powder in it, and press it. Throughout this process, the metal parts continue to dissipate a large amount of heat, and eventually the temperature will be 20 degrees lower than originally expected.

I often say, "the handle must be locked on the machine when it is useless" in order to keep the temperature constant. When opening a shop to do business, the filter basket of coffee powder must not be left idle on the counter. One day you go to an espresso coffee shop and find the handle of the filter handle lying safely on the lift.

Let's not! Let's go to another cafe.

Set temperature-

Since it is impossible to use a thermometer to measure the water temperature of the espresso machine, you have to pay for a lightweight digital thermometer that can quickly and accurately measure the tip of the probe. For example, the Fluke 51 thermometer, if you can get it, refer to my method.

The ideal method is to bury the thermocouple sensor directly in the filled coffee cake. In this way, when making coffee, you can monitor the change of water temperature at any time. Make a small hole under the coffee filter basket, just enough to pass through the sensing line. The smaller the hole, the better. The pressed coffee powder will automatically fill the gap in the small hole, not bad! Lift the probe tip up, near the upper surface of the coffee cake.

When most heat exchanger machines are idle, heat slowly accumulates in the outlet head. So the temperature will be higher than the set value.

When there is a dedicated water boiler machine idle, the outlet head temperature will be 3 to 4 ℉ lower than the set value.

Temperature change-

In order to keep the water temperature of the filter cake through the handle stable, a very careful and complicated method is needed. This is the difference between the so-called "good" bar and the "master" bar. It's intuitive, but there are still some techniques available.

If the machine I use rushes out 2 ounces of hot water, throw it away immediately. Flush out another 2 ounces of hot water, repeat operation, the temperature is about the same. If used in this way, the temperature change of the outlet head can be minimized. (the basic idea is to keep the idle temperature of the outlet head as close as possible to the working temperature.) Note: do not use more than 2 ounces of hot water at a time.

The longer the machine is idle, the more the temperature of the outlet head deviates. The better the machine, the less deviation.

Commercial espresso machines are designed for continuous use. The more often the machine is used, the more stable the output temperature is.

In Italy, it is rare to see espresso machines with less than three water heads. The bigger the machine, the greater the mass, the more hot water, the more stable the temperature of the outlet head. To make coffee well, I suggest that the machine used at the bar should not be too small (no less than three water heads).

Keep the handle warm-

If you make a second cup of espresso after a few minutes, use your time to grind the beans, start the pump and pump 2 ounces of hot water to preheat the handle and used coffee cakes. Let's leave the used coffee powder in the handle before we cook the next cup of espresso, no doubt! Because the residue itself is hot, it helps to keep the hand warm.

When you take off the handle to fill the new coffee powder, act quickly and accurately:

* knock out the old powder, put in an appropriate dose, and compact

* start the pump and flow out 2 ounces of hot water

* quickly lock the handle

* start the pump immediately

(chapter 21 of this book, "the way we cook espresso" will repeat the whole step.)

If you lose too much hot water, there will be trouble-

It is mentioned earlier to knock out the old powder, but there will still be some chips attached to the filter basket. The people in our store wipe it off quickly with their fingers, but some people start the pump and wash the residue with hot water. This is wrong! Because this will lead to excessive changes in the water temperature of the machine.

The espresso machine can keep the temperature as stable as possible, but it is limited to using 1 or 2 ounces of hot water at a time. Using too much hot water at a time is really not a good idea to use a machine. So when I mention "using hot water", I always stress that it should not exceed 2 ounces.

If the coffee powder forms a small lump and sticks, it can be flushed with hot water from a steam boiler. This has other benefits: the handle temperature is further raised.

If you think there is something wrong with the water temperature of the machine, ask the technician of the agent to help adjust the heat exchanger type espresso machine and adjust the temperature of the steam boiler.

ESPRESSO COFFEE: Professional Techniques

(Ⅷ)

Chapter 8

Cleaning machines-- the second golden rule--

As long as the coffee liquid touches the surface, the coffee oil will continue to stick to it. Because of its unstable chemical properties, the accumulated grease will soon become bitter. When freshly brewed coffee comes into contact with these old oils, it will smell rotten.

The bad news is that there is a widespread problem of dirty machines in American cafes.

The good news is that this problem is easy to solve, as long as you are diligent in cleaning and "cooking" again.

The chef of the restaurant will check the plate when he has nothing to do, and is always required to be clean. The same espresso bar should look at the filter handle and outlet head with the same mentality. But it can't be completely free of coffee grease, lest espresso come into direct contact with the exposed metal surface. Therefore, every time you clean the filter handle and use espresso special detergent to backwash, brew the coffee once and then pour it out.

This chapter focuses on the cleaning steps after closing every day, and other cleaning work that must be carried out on a regular basis. Chapter 17 of this book will show you how to operate the machine to keep it clean.

a. Filter handle-

When you usually make coffee, you have to wash it every hour. After closing every day, dissolve it in hot water with a spoonful of detergent. Separate the coffee filter from the handle and soak in it overnight. When soaking, do not soak the plastic part of the hand, so as not to be eroded by the detergent.) The next morning, scrub hard with Scotch Brite (for washing glass). Use a small bottle brush to reach into the small passage of the handle outlet and brush off the small pieces of debris that stick to it.

Form a good habit of cleaning every night so that coffee oil will not accumulate. Otherwise, if the grease slowly accumulates and forms a hard lump and sticks to the outlet, it will be very difficult to clean up.

If the filter handle is dirty, the appearance and taste of the espresso will change, the crema is less, and there will be white lines. (see Chapter 17 of this book-cleaning techniques)

b. Do backwash with espresso special detergent-

There is a gadget called "non-porous filter" (it looks like an ordinary filter, but there are no holes in it.) Remove the general filter from the handle and put it into the non-porous filter to block the water pressure of the pump and let the water flow back out of the head.

Modern boiler-type espresso machines have valves and drainage lines for releasing remaining high-pressure hot water. Otherwise, after you finish this cup, when you plan to cook the next cup and take off the handle of the filter, the high-pressure hot water will flush out and spray the brewed coffee powder everywhere. So after cooking a cup, there must be a pressure relief valve to release the pressure. This valve and associated piping, located behind the hot water dispersion screen of the outlet head, are collectively referred to as the "countercurrent system". When brewing water flows out, the effluent system, coffee and countercurrent system share a set of piping. This common pipeline will deposit coffee grease and give off a rancid smell after oxidation.

There is already a special detergent for espresso to dissolve and wash away the grease that has accumulated in the pipeline valves. The main ingredients of the detergent are:

Sodium phosphate

Foaming agent (for cushioning)

Other compounds (used to strengthen cleaning power to protect washers and other soft parts from sodium phosphate)

How often do you wash backwards?

Do it at least once every night at closing time. Use according to the instructions of the cleaner. (there will be different cleaning methods for different machines, depending on which machine you are, use the method specified by it)

We put a tablespoon of detergent in the porous filter, put it in the filter handle, lock the handle, start the pump for 30 seconds, and turn off the pump. Wait for the pressure to release, then start the pump. Repeat this twice at intervals of 3 to 4 seconds.

After cleaning, don't forget to rinse the water head before making coffee. Remove the porous filter and rinse it with hot water. Then briefly turn on / off the pump several times until the outlet head has been washed clean. Then put the clean perforated filter back on the handle and lock it. Start the pump for 5 seconds and turn off the pump. Repeat this five times. (to be clean, the countercurrent system should be flushed with clean water at least 5 times.)

Maybe you need to wash it with detergent a few more times during business hours. Drink your own coffee often in order to determine the appropriate cleaning interval. Our store is cleared every four business hours. (please see Chapter 17 of this book for details.)

c. Water diversion network-

Remove the water distribution network and clean it every night, then clean the fixing screw and outlet head.

d. Washers-

After removing the water diversion net, you can see that there is a gasket. It is used to seal the gap between the outlet head and the handle of the filter basket to prevent high-pressure water from seeping out. Clean the gasket with a small stiff brush. (many manufacturers and agents sell special brushes)

e. Outlet head-

After removing the water diversion net, you can see a large brass structure (which may also be made of other metals), which is the outlet head. Clean it with Scotch Brite every night.

f. Steam sprinkler-

After closing every night, remove the steam sprinkler and clean the steam out of the hole with a pin or brush. Then use a small brush to pass through the steam pipe, and many technicians will advise you to soak the whole steam stick in water overnight to soften and peel off the hard lumps that stick to it. This is not good because there will be problems: if the electricity of the house is also turned off, the boiler will cool, and then the dirty water will be sucked back from the water container through the steam tube back to the boiler.

In a word, develop good cleaning habits. Do this cleaning work with your bar buddies every night, and the coffee can be made to maintain its consistent high quality. It can prolong the life of the machine and increase the reliability of the machine. Pay attention to the filtration of water quality and be regularly overhauled by technicians trained by the original factory. You can use Tian Chang Di Jiu (Eternal Dumpling) on your commercial espresso machine.