Espresso Coffee Jargon and Terminology Explained
Feel like you have fallen into a vortex lately, in your attempts to figure this, that, and the other thing out about espresso machines?
Trying to get a grip on what some of the things associated with making espresso, such as maybe what a portafilter is, a dual boiler, or even an Americano beverage, definitely gets rather confusing for most people new to the world of espresso.
Below is a complete compilation of all these weird words put together all in one happy place!
If you have been searching for an espresso machine and have been seeing all kinds of strange words that you have never seen before, this page is devoted to just simply defining and unraveling the mystery of all of these words. Therefore, below is a complete listing of all the espresso coffee jargon and terminology explained, all in one convenient place.
You will likely find that some of the things you thought were so important when choosing an espresso machine are actually not so important after all, while other things that you felt might not be important turn out to be much more important than you had thought.
The world is full of different jargon for different things that people are involved in.
Computer geeks like to talk about things like RAM and CPU…
Website making fanatics speak of things such as SEO and Analytics…
Doctors like to use big words, such as lumbosacral, spondylolisthesis, radiculopathy, and whatnot…
…and on and on and on.
There is also a very individualized, and somewhat expansive, line of jargon devoted completely to the world of java/espresso. Even deciding on what type of espresso beverage to purchase can become somewhat dizzifying at times, if you are not familiar with the terminology involved.
Espresso Coffee Jargon and Terminology Explained
This espresso glossary is definitely a work in progress. Feel free to check back from time to time, as this list will be added to on a daily basis until every single thing we can come up with has been included.
In a nutshell, the definition of an Americano is a shot of espresso diluted with hot water. You probably at this point are thinking to yourself, “Well, isn’t that just normal coffee?”
However, the resulting beverage, when hot water is added to dilute an espresso, is not identical to that of coffee. Espresso has a different flavor than, say, drip-made coffee. Therefore, when you combine some hot water with an espresso, the resulting beverage takes on a more espresso-like flavor, even though it has about the same strength as “normal American coffee.”
Most espresso connoisseurs agree that an Americano has a different (and much better) flavor.
Automatic (or Auto) Espresso Machine
Refers to a type of espresso machine that requires the user of the machine to grind whole coffee beans with a grinder, dose (place) the ground coffee into the place where the ground coffee goes (called a portafilter), and tamp (compress) the coffee grounds into the portafilter.
Doesn’t sound so automatic, right? Well, the automatic part comes into play after the above has been done by the user, and includes the brew volume, which is pre-set by the user via a setting on the machine so that the required pressure is automatically set.If comparing an automatic espresso machine to a “super-automatic” espresso machine. With espresso machines that are not classified as automatic (in other words, manual/lever espresso machines), the brew volume is manually controlled by the person using the machine, with a lever.
Note that the user of a super-auto machine in most cases is not required to grind, dose, or tamp the coffee, as a super-auto machine normally will do all of these things for you, whether it be via a built-in grinder or with the use of pre-packaged E.S.E. pods.
A barista is the person who brews espresso in a shop such as Starbucks.
Most espresso machines have some level of bar-pump pressure associated with them. A 9-bar pump pressure is the standard minimum for successful espresso brewing, and is equal to approximately 130 pounds of pressure per square inch.
Although most home espresso machines available in today’s marketplace have either 15 or 19 bars of pump pressure, these numbers are not truly necessary to brewing great espresso.
Manual (lever) espresso machines normally never provide 15 or 19 bars of pressure, and are able to brew top-notch espresso even better than that which the semi-auto and super-auto machines brew up.
Also just called a hopper, a bean hopper for an espresso machine is simply a container attached to the espresso machine in which whole coffee beans are stored, and then subsequently dispensed from the bean hopper down towards and into a built-in grinder, where they are then ground and dispensed into a portafilter prior to brewing an espresso shot.
The boiler of an espresso machine is the component of the espresso machine that heats the water for brewing espresso and steaming milk.
Most espresso machine boilers are located inside a housing/casing box that covers the exterior of the machine, with the exception of a majority of manual/lever machines such as this one, which normally have the boiler exposed as part of the outside of the machine.
Boilers can be found made of brass, copper, aluminum, or stainless steel, depending on which machine you choose. Most manufacturers provide information regarding the material the boiler is made out of for any given machine.
The majority of people who have used a number of different espresso machines feel strongly about their preferred boiler material. These opinions vary among different people, and there is not one single recommendation that can be made regarding which would be the best boiler.
For example, some people feel that stainless steel is much more preferable than aluminum, while others feel that aluminum is much more preferable than stainless steel. People who prefer stainless steel boilers over aluminum ones, for instance, feel that stainless steel is more “safe” than aluminum.
If choosing an espresso machine for yourself, you will need to make the call as to what you consider to be your top choice as far as boiler material is concerned. There are top-rated machines that include boilers made of all of the above materials.
In a nutshell, the brew group is an assembly of components that, when put together, cause the circulation of the water inside the machine and move it down through the ground coffee contained in the portafilter. while at the same time maintaining the temperature of the water that is heated in the boiler, after which it is transferred into the brew group via a pump. The brew group then drizzles/showers hot water that has been pressurized through a component of the brew group called a diffusion plate, after which the water moves to and through the ground coffee in the portafilter and into a waiting cup (or cups) below.
Brew group parts include the grouphead (the part of the brew group containing the mechanism that locks the portafilter in place just prior to brewing), as well as the portafilter itself, and the filter basket.
Properly brewing espresso requires all components of the brew group to be heated, prior to the actual brewing process. This takes place as a result of the hot water heated in the boiler going through the brew group components. Part of the brew group’s responsibility is to maintain that perfect water temperature of around 200 degrees after it has been heat to that temperature in the boiler and then transferred to the brew group.
A lot of super-automatic home espresso machines have what is called a “removable brew group,” which allows for easy removal and cleaning.
Brew (or Brewing) Temperature
One component of successfully brewing the perfect cup of espresso is to ensure that the brewing temperature of the water is correct.
Different people have varied opinions as to what the actual “perfect” brew temperature should be utilized. Overall, however, most people “in the know” agree that a great shot of espresso is one that is brewed with water that has been heated to a temperature between 190 and 205 degrees Fahrenheit.
The term brew-ready simply refers to water that has been heated in the boiler of an espresso machine and has reached a hot enough temperature that is ready for it to be used to brew espresso(s).
Brew time is the amount of time that passes between when the pump is first activated (via a switch) to the time when the pump is no longer needed and is switched off.
Another way to define brew time would be to explain it as being the amount of time that passes while the ground coffee is in actual contact with the water being extracted through the grounds.
A brew time that is either too short or too long will result in suboptimal flavor (either too weak or too strong).
Correctly brewed espresso normally has a brew time of approximately 25 to 30 seconds from start to finish.If the flavor of your brewed espresso is not top-notch, one key factor to consider should be the amount of brew time that it took to finish a shot from the time the water started being pumped to the end.
A burr grinder is comprised of two disk-type components — one of the disks is stationary (stays in one place without moving), while the other rotates in a circle and grinds whole coffee beans into coffee grounds, prior to the espresso brewing process.
Some home espresso machines have built-in grinders, normally “conical” burr grinders.
There are also many different coffee bean grinders available. If you are serious about making good espresso, you will likely need to consider purchasing a very good quality grinder that has a high number of different grind settings, and one which is at least in the medium price range.
A caffe latte (or just simply latte) is a combination of a shot (or two or even more) of espresso combined with milk that has been steamed.
Lattes are a very popular “thing” to order, particularly with flavored syrups added, such as hazelnut.
A caffe mocha (just called a mocha by most) is just simply an espresso that has been flavored with chocolate, normally chocolate syrup. Whipped cream is another great option that many people choose to have their mochas topped with.
A cappuccino is a beverage that is made up of ingredients including a third of it being espresso, a third of it frothed milk, and a third of it steamed milk.
Very popular toppings for a cappuccino include powdered chocolate and/or cinnamon.
Also referred to as “coffee pack,” the term coffee bed simply refers to ground coffee that has been tamped into a portafilter with basket just prior to brewing espresso.
This is the description meaning the tamped amount (volume) of ground coffee in a portafilter basket just prior to brewing the espresso.
Commercial Espresso Machine This is the name for an espresso machine that is used professionally to make espressos, such as the ones at Starbucks. Machines that are commercial grade have the ability to continuously brew up shots of espresso, one right after the other, for the entire day if needed, without wait time in between shots.
Consumer Espresso Machine (meaning home espresso machine for the average consumer
The term consumer espresso machine represents a standard home espresso machine, the type that “consumers” would normally consider buying.
Consumer (home) espresso machines are normally much smaller and much less expensive than professional “commercial” espresso machines.
Just like most any piece of equipment that requires controls to operate, such as the picture to your left of a standard kitchen microwave, the control panel of an espresso machine is normally located on the front of the machine and can consist of dials, buttons, and/or LED displays.
The control panel allows the home barista to switch the machine on and off, as well as allowing for many other possible settings, depending on the machine and the espresso beverage desired.
Crema is a creamy, brownish top layer of foam that is a MUST for good espresso. To your left is a great image of crema.
Although you may have thought that crema is the frothed milk that is added to a shot of espresso, this is incorrect.
The presence of crema (or the lack of) can either make or break a shot of espresso. A “good” shot of espresso ALWAYS has a top layer of crema.
Cup Warming Tray
Also called a “cup tray” or a “cup warmer,” a cup warming tray is an integrated part of some espresso machine that heats espresso cups to a warm temperature prior to dispensing espresso into them.
The cup warming tray of an espresso machine is normally located on the top of the machine, such as the one in the picture to your left. The warming process takes place as a result of the heat from the inside of the espresso machine traveling upward toward the cups. Also makes a very handy place to store espresso cups when the machine is not in use. Many people will only consider a home espresso machine with a cup warming tray, as it is considered very beneficial to warm espresso cups prior to serving espresso into them.
A demitasse espresso cup is the traditional cup used for serving espresso. Demitasse (meaning small cup) cups normally hold just up to 3 ounces of beverage. The most popular and preferred ones are made of porcelain, although you can find demitasse cups made of glass, ceramic, or stainless steel.
One important factor to note is the thickness of the demitasse cups you are considering, and keep in mind that the thicker the porcelain (or your choice of material), the better heat retention you will get. Due to the small amount of beverage these cups are able to hold, heat retention is very important.
The dispersion screen is a must for ALL espresso machines, and is basically part of the brew group that is responsible for evenly “showering” hot water into the portafilter holding the ground coffee and the filter basket so that all coffee in the portafilter is evenly moistened all at the same time.
This term refers to the amount of ground coffee beans that are used for a shot of espresso. Normally, a single 1.5-ounce shot of espresso utilizes 7 grams of ground coffee.
Doser This word prefers to a mechanism found with burr grinders, particularly burr grinders used with espresso machines, which supplies the correct amount of ground coffee to be brewed into an espresso beverage.
Also referred to as a “double shot,” meaning an espresso beverage that has between 2-1/2 and 3 ounces of espresso beverage, as opposed to a “single” shot, which normally has 1 to 1-1/2 ounces of espresso beverage.
The drip tray of an espresso machine does just what it sounds like – a tray that catches drips that are bound to occur when espresso is made. The drip tray of an espresso machine is located directly underneath where the espresso is dispensed from the machine into waiting cups.
It is normally a screened area or an area with holes that the cup sits upon, as in the image to the left, which allows drips to be caught into a place for later disposal. Most drip trays are constructed of either plastic or metal, and most are easily removable for a quick dump and rinse.
Also called an E61 brew group, this is the essential part of espresso machines. When an espresso machine is in use, the brew group first is heated via means of circulating hot water that enters it from the boiler, which greatly helps with ensuring water temperature stability at the correct temperature needed to brew espresso. The brew group also controls pre-infusion.
We find it very difficult to explain, in simple terms, what EXACTLY the brew group does. The most simple, basic explanation we could come up with, so that almost anyone reading this can understand it (us included) is to say that the brew group is introduced with water that has been pre-heated to the needed temperature in a boiler inside the machine, where the brew group maintains that needed water temperature.
After that, the pre-infusion occurs within the brew group. Pre-infusion (moistening the coffee grounds for a set period of time) is the process by which the heated water is run down through the brew group to what is called the “dispersion screen,” where the pre-infusion then takes place.
After pre-infusion, the brew process takes place where the water is run through the grounds, the flavor is extracted, and the brewed espresso is dispensed through the portafilter and out of the brew group into espresso cups below the brew group. Hope this helps!
Espresso is defined as a strong coffee that is produced by forcing steam through coffee grounds with either a manual (lever) machine, or a machine with a pump.
Espresso is normally comprised of approximately 7 grams of coffee beans that have been finely ground through which water/steam extracts approximately 1.0 to 1.5 ounces of beverage at an ideal temperature of between 195 and 205 degrees Fahrenheit.
Extraction is the process of forcing hot water/steam, once it has been heated in the machine’s boiler, down through the coffee grounds, causing espresso flavor, oils, lipids, etc., to be “extracted” from the mixture of steam/water and the ground coffee beans, which results in espresso.
Extraction time (also called brew time, and you can refer to Brew Time above), pertains to how much time has passed from the time the pump is first activated until the time that the pump is switched off.
Another way to explain extraction time is to explain it as being the amount of time that passes while the coffee grounds are in contact with the steam/water while it is being extracted through the grounds.
If you are using a machine, keep in mind that the necessary extraction/brew time needs to be approximately 25-30 seconds from start to finish. If it is a longer amount of time than 30 seconds, or shorter than 25 seconds, your end result (the espresso) will not have that desired espresso flavor you are likely attempting to achieve.
Also called a “portafilter basket,” this is a small round, metal insert that is placed inside a portafilter and holds the ground coffee. If you look closely at the image on the left, you might (or might not, as the picture is pretty small) see that there are many tiny holes in the bottom of the basket. This allows for the extracted espresso beverage to seep down towards the spout, where the espresso is dispensed into a cup.
A good majority of espresso machines have two portafilter baskets — one for single shots and one for double shots. Other machines come with only one basket that is interchangeable and allows for making either a single or double shot with the same basket.
Foam (which is also referred to by many as “froth”) represents the steamed/whipped milk that is added to many espresso beverages. Another term that means the same thing is “froth” or “milk froth.”
Foam/froth is made as a result of steaming milk with a steaming wand (sometimes called a frothing wand) of an espresso machine. The wand used to make milk “foam” not only injects steam into the milk, it also has holes so that air can be introduced into the milk at the same time that steam is.
You will note in the image to the left that the barista is adding frothed milk to an already brewed espresso by pouring the frothed milk, not by spooning or any other method. Never should milk foam/froth be spooned out in “clumps” or be able to be shaped (kind of like meringue); rather, it should be definitely pourable if it has been done correct.
Refers to the white milk froth that is the end result when milk is “frothed” (also called foamed or steamed) with the milk-frothing (steaming) wand of an espresso machine.
See “Foam” directly above this entry for additional details regarding froth.
Also called milk warmers or steaming pitchers, frothing pitchers are small pitchers usually constructed of high-quality stainless steel, used for steaming/frothing milk in.
Frothing pitchers are available in different sizes, starting at approximately 12 ounces.
This terminology refers to the tip of a frothing/steaming wand, which normally has tiny holes in it, allowing the air that is carried through the wand to escape through the tiny holes and inject into the milk that is being frothed.
The holes on these wands vary, and are usually either pointing straight down or angled to one side. The entire purpose of these holes is to allow injection of air into milk during the frothing process.
Another term for “brew group.”
The brew group is basically a component in an espresso machine where the water heated in the boiler is pumped into. The brew group maintains the hot temperature of the water while at the same time controlling the pre-infusion (moistening of the grounds prior to brewing), then followed by the actual brewing process.
Simply means the amount of heating time that an espresso machine takes to heat water to the appropriate temperature after the machine has been switched on.
How quick the heat-up time for a particular espresso machine is, is largely dependent on the site of the boiler in the machine.
With the smaller espresso machines, such as those made by Nespresso, which are normally single-serve machines and require very little water to make a single espresso, heat-up time can be as quick at one or two minutes.
Machines with larger boilers (some machines have boilers that hold up to 80 ounces of water), on the other hand, can take upwards of half an hour before they are brew-ready.
However, a larger boiler in a machine, although requiring more time to heat up, normally also is accompanied by better water temperature stability and a quicker “recovery time,” which means less waiting between shots if you are brewing up a few at a time.
Also called a “bean hopper,” this refers to a container built in to an espresso machine that holds the whole coffee beans. The whole beans are normally dispensed from the bean hopper directly down toward the grinder, where they are then ground by a built-in grinder.
Most bean hoppers can be sealed tightly, which helps to preserve the freshness of the coffee beans inside.
Bean hoppers are normally filled by lifting a lid located at the top, pouring in the beans, and then simply storing them in there until the machine is used.
The housing or “casing” consists of both the outside “shell” (cover) of the machine and the structure inside the shell that supports the shell.
Espresso machine housing is generally made of either heat-safe, somewhat heavy-duty plastic, or of different types of metal which could include aluminum, stainless steel, brass, or iron, depending on the machine.
Due to today’s advanced technology, many of the housings you see on espresso machines can APPEAR to be metal when they are, in fact, actually plastic that has been manufacture to present with the appearance of metal.
A knockbox (or knock box) is a metal box-like container that has a bar affixed across the top of it, for “knocking” the spent grounds puck in the portafilter on after an espresso shot has been brewed.
A latte is an espresso beverage with the same meaning as a “caffe latte.”
A latte (caffe latte) is a beverage consisting of a combination of espresso shot(s), steamed milk, milk foam, and sometimes flavored syrup.
In the world of espresso machines, the term “lever” normally refers to what can also be called a “manual” espresso machine.
A lever/manual espresso machine is one which has no pump inside, and the pumping of the water is instead done by the barista who is making the espresso, by means of lowering a large lever on the outside of the machine.
Lungo, the Italian term for “long,” means “long” extraction of coffee flavor with the same amount of coffee (7 grams) and much more water (50 mL for a lungo as opposed to 25 mL for a standard espresso).
So, in other words, for a lungo, the same amount of ground coffee is used with about twice as much water as normal.
The word manual in the world of espresso machines refers to a particular classification of espresso machines that require the barista (user of the machine) to “manually” do the pumping of the water heated in the machine via a lever, as opposed to an electric water pump inside the machine pumping the water where it needs to go after it is heated.
A mocha is identical to what we describe as a “Caffe Mocha” above in this chart.
A mocha is basically an incredibly scrumptious beverage that is a combo of espresso and chocolate syrup. Whipped cream topping is another great consideration when making a mocha!
Also called a “stovetop espresso maker,” Moka pots are normally used on a standard electric or gas stove to make coffee that is stronger than normal coffee (although there are electric ones that plug into an outlet rather than being used on the stove).
Although many people call them stovetop espresso makers, they basically are just a way to make coffee that is stronger than espresso, and we don’t feel they are truly an espresso maker.
Over-Extraction or Over-Extracted
Refers to espresso that has had the ground coffee exposed to hot water for a period of time longer than what should have occurred.
Over-extraction of espresso (or even coffee, for that matter) usually results in espresso or coffee that has a burnt and/or bitter flavor to it.
You likely wouldn’t really want to consume over-extracted espresso any more than you would want to eat that piece of toast over there! Bluck!
In the world of espresso, a piston is the component through which hot water is forced at a high pressure into and through ground coffee awaiting in the portafilter.
This is the terminology used which means, simply, an espresso maker that has a water line attached to the main water line in your residence, or to other supplies available in a house, such as a water bottle.
This is similar to your sink faucets, bath tub, and shower, which are also all “plumbed in.” Most commercial espresso machines, such as the ones you see at Starbucks, are plumbed in, although there are some home machines that can be plumbed in also.
Also see “Portafilter” below. A portafilter is a container that holds ground coffee prior to and during the espresso brewing process.
A “pod portafilter” is simply a modified portafilter or portafilter adaptor that allows for using today’s popular easy serve espresso (E.S.E.) pods. These images to your right are coffee capsules/pods with which a pod portafilter would be used.
A portafilter (or porta-filter) (also sometimes called a “groupo) is a small, bowl-like container with a handle into which finely ground coffee is placed and then compressed (tamped), after which the portafilter is inserted into a place below the brew group. Hot water is then introduced into and through the grounds, flavor is extracted from the ground coffee, and the extracted espresso then leaves the portafilter out of spouts pointing downward out of the bottom of the portafilter, and the espresso is dispensed into the cup(s) waiting below.
Portafilters can be found made of chrome-plated copper or brass, as well as aluminum, steel, other metals, and yes, sometimes even heat-safe plastics.
A portafilter sneeze is the result of someone removing from the machine the portafilter too soon after brewing a shot of espresso, which can sometimes have an end result of instantly releasing brewhead pressure, which ultimately results in wet, hot ground coffee spraying, which will most likely cause burns.
This generally occurs with manual pump/piston machines that do not have a system for releasing the water pressure that builds up in the machine. For these types of machines, it is best to wait at least one-half to one minute after brewing before removing the portafilter, in order to allow the pressure to decrease.
The term pre-infusion refers to the process during which ground coffee that has been tamped into the portafilter is “showered” for about one to two seconds with heated water in the machine, prior to the actual brewing process, followed by a one- to two-second pause after the grounds have been pre-infused, after which the actual brewing process of running the heated water through the grounds begins.
Super-auto and some of the available automatic espresso makers which complete the pre-infusion via the pump inside the machine, which pumps water to the coffee grounds for one to two seconds. The pump then stops for another second or two, and then starts pumping again at which point the brewing of espresso continues.
Some of the espresso machines available nowadays have the option of a pressurized filter (portafilter), which basically moves all espresso after it has been extracted down to a waiting cup through a tiny single hole, which results in additional “crema” being produced than there would have been without the use of the pressurized portafilter, due to the jet action caused by having just a single hole for the extracted espresso to shoot through.
Also referred to as a “dry puck” or a “spent puck,” this is simply a tightly packed puck-shaped bed of grounds after the espresso brewing process has been completed.
This is a word that describes the actual brewing of a shot of espresso, which originated from espresso’s early beginnings and always required the barista to “pull” on a lever of an espresso machine. Although there are still quite a few espresso machines that require the barista to pull on a lever (for those brave enough to attempt to use a manual/lever espresso machine), a good majority of espresso machines nowadays don’t require the barista to “pull” a shot.
All home espresso machines, except for manual/lever machines, have a pump. The primary function of the pump is to pump water with the correct pressure required for properly brewing a good shot of espresso, which is 135 pounds per square inch (PSI).
There are basically two different types of pumps that can perform this function, including vibratory pumps and rotary pumps.
This term simply means how much wait time is needed between brewing espresso shots, if one is brewing more than one at a time. “Recovery” refers to how long the water takes to “recover” to the needed hot temperature.
A faster recovery time is enjoyed when the espresso machine one is using has a larger boiler, a more powerful heating element, or a heat exchanger system.
The word ristretto means a “short” (or restricted) shot of espresso utilizing the normal amount of ground coffee that would be used for a double shot (14 grams), although the end result is approximately only 1-1/2 ounces of espresso, making for a very much more flavorful, stronger, and richer espresso beverage.
Brewing a quality ristretto requires much practice, and those who have the ability to make a perfect ristretto, without stalling the espresso machine, are few and far between.
Also called volumetric pumps, rotary pumps are the primary type of pump used in commercial espresso machines, and are the more powerful of the pumps used for espresso machines.
Rotary pumps require the machine they are used in to be plumbed in with their own pressurized water line. Therefore, stand-alone home espresso machines that have water poured into them by the home barista do not have a rotary pump.
Also referred to as semi-auto espresso machine, this classification refers to machines on which the espresso shot pressure is controlled automatically by the machine. The brewing temperature is also controlled automatically by the machine. On the other hand, brew-time length on a semi-auto machine is controlled manually by the person brewing the espresso.
A shot for the purposes of this espresso machine glossary is simply a cup of brewed espresso, comprised of 1 to 1.25 ounces of water brewed with 7 grams of finely ground coffee.
The term “single” refers to a “single shot” of espresso, which generally includes a combination of 7 grams of ground coffee brewed with 1 to 1.25 ounces of water.
Also referred to as “puck,” a spent puck is the end result after an espresso has been brewed, basically coffee grounds that are tightly packed and puck-shaped, normally easily removable from the portafilter in one piece and ready for disposal.
In addition, there are tons of other great uses for spent pucks, other than just throwing them away. Although we haven’t yet covered the different uses for spent pucks and coffee grounds in an article, it’s on our “radar” and will be written soon.
Spout or Spouts
This is the part of the machine, actually part of the portafilter, through which the brewed espresso is dispensed into waiting cups below. Most standard portafilters come with two spouts, which allows for brewing either two single shots or one double shot, although there are portafilters available that have just one spout.
Stall or Stalling
Stalling is something that happens when the coffee beans being used have been ground too finely and/or tamped (compressed) too tightly in the portafilter. These factors cause the espresso machine pump to be unable to produce sufficient pressure to force the water through the ground coffee, which results in a machine “stall.”
Stalling occurs most frequently when a barista is attempting to brew a ristretto, which is an extremely strong espresso beverage that uses approximately the same amount of water as a single shot of espresso in combination with about twice the amount of ground coffee (14 grams of coffee is used for a ristretto vs. 7 grams of coffee for a standard single espresso shot.
Most of the espresso machines that have a steaming/milk frothing capability have what is called a steam knob, which controls the steam valve opening and closing.
Turning the steam knob allows for increasing or decreasing the amount of pressure built up by steam, thus allowing control of how much steam is used to froth/steam milk.
Steam (or Steaming) Wand
A steam wand (also called a frothing wand or steaming wand) is a metal wand that is on the outside of the machine used for frothing/steaming/foaming milk to be added to espresso beverages. These metal wands are sometimes also covered with a plastic cover, which many people dislike due to milk becoming dried and stuck on the plastic much more so than on the metal. Some steam wands can also be used to heat water.
Super Automatic (or Super Auto)
A classification of espresso machine that basically does everything for the barista, to include grinding, dosing, tamping, brewing, and ejecting the spent puck of ground coffee after the brewing process has finished.
Some super-auto espresso machines also feature an automatic frothing capability via a milk container that is attached to the machine, leaving no need for the person brewing the espresso to froth the milk manually with a wand.
In a nutshell, super-automatic home espresso machines basically do all of the work for you, requiring you to just add water and milk to the appropriate places, place the cups where the espresso will be dispensed, and then push some buttons or turn some dials.
The term tamp refers to the compression of finely ground coffee into a portafilter with a necessary espresso machine accessory called a “tamper” (see entry right below this one for the description of a tamper).
Different grinds of coffee, as well as different machines, require different types of tamping, primarily referring to how much tamping/compression of the grounds needs to take place to successfully brew a good espresso beverage.
For example, manual/lever espresso machines require more of a compacted tamp, while machines such as steam-driven ones utilize a more lightly tamped/compressed bed of ground coffee.
A tamper is the necessary accessory that one must have with manual and semi-automatic espresso machines. A tamper is used to “tamp” (compress) loose coffee grounds in a portafilter just prior to beginning the espresso brewing process.
Although the preferable tampers are made of metal, you can find ones made of plastic — usually the plastic tampers are the ones that come with a machine when it is purchased.
Tampers always come in millimeter sizes, with the most common being 58mm, 57mm, 53 mm, and 49mm. The millimeters refer to the diameter across the part that does the tamping. When considering the purchase of a tamper, it is necessary to absolutely, positively know what size you need to obtain for any particular espresso machine. If the tamper acquired is too large (for example, a tamper that is 58 mm for a portafilter/basket that has a 53 mm diameter), then tamping will not be able to be completed due to the tamper not fitting into the portafilter. Therefore, it is very important to know what size portafilter/basket you are working with before buying a tamper.
Stability of temperature refers to the capability of an espresso machine to keep a steady, even water temperature as the water travels throughout the machine, from the boiler to the grouphead during the brewing process. Higher-end home machines, as well as commercial machines, definitely provide greater temperature stability.
The better the temperature stability is, the greater chance of success one will have, particularly when brewing many shots of espresso in a row, one after the other.
Thermoblock (or Thermocoil) – these two terms mean the same thing
You will find a pretty large number of home espresso machines in which the water-heating system is called a Thermoblock. Another term meaning the same thing as Thermoblock is Thermocoil.
This type of heating system heats the water for brewing espresso via metal coils through which water passes through and is progressively heated to a high temperature until adequate temperature has been achieved. You can compare a Thermoblock heating system in an espresso machine to that of the radiator in an automobile or one of those old-time home radiator heaters, where water runs through several different chambers during the heating process. The image to your left is MOST DEFINITELY NOT a Thermoblock system you will ever find in any espresso machine — the image to the left is, instead, simply a photo of a home radiator heater in our attempt to give you a sense of what we are trying to convey.
Under-Extracted or Under-Extraction
A term that simply refers to an espresso beverage that results when insufficient exposure of the water to the ground coffee, which results in espresso that is weak rather than strong.
Also called a vibration pump, this is a type of pump commonly found in espresso machines that have water tanks/reservoirs into which water is poured by the home barista, although there are a few plumbed-in machines that also utilize this type of pump.
A vibratory pump, when compared to its counterpart, the rotary pump, is a smaller pump that won’t handle brewing hundreds of espresso beverages needed, such as those used in Starbucks. Vibratory pumps can typically handle up to about 40 brews per day. They are also much less costly to replace than rotary pumps.
This is just another name for a rotary pump. Volumetric pumps, like rotary pumps, are primarily found in commercial espresso machines. Volumetric/rotary pumps are able to handle many more brews per day than their counterparts, the vibratory pumps.
A large majority of espresso machines feature some kind of water filtration system, which filters out impurities, chlorine, etc., in the water being used, resulting in more pure, and better-tasting espresso.
There are very advanced water filter systems in some machines, such as filters that use charcoal.
There are also some very “simple” and unsophisticated water-filtering systems in some machines. These ones are simply made up of a metal filter screen mesh type component.
Water Reservoir (or Water Tank)
All espresso machines that are not hooked to plumbed-in systems have a water reservoir/water tank, the sole purpose of which is to hold water that has been poured in by the person brewing up the espresso, prior to starting the espresso brewing process.
The water in the reservoir is used for the extraction of coffee from ground beans, as well as to provide steam for frothing milk on those machines that have frothing/steaming capability.
Some higher-end espresso makers have a water-softening feature, which is basically a type of filtering system that softens water. Softening of water helps greatly in assisting build-up of limescale in other areas of the machine, which greatly reduces the frequency of needed machine descaling.