An Espresso Glossary

State of Coffee

Originally published in 2002 and updated over a dozen times since, this espresso glossary has become a reference point for several books on coffee and espresso, and has been widely referenced and copied across the internet. Fully updated for CoffeeGeek’s re-launch in late 2020, it has seen its most recent update in June, 2021.

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Back in 2003, we published an initial Espresso Glossary on CoffeeGeek that had about 35 entries detailing some of the more arcane (as well as common) terminology relating to espresso. It was updated at least a dozen times over the following five years, and was used as research and background info for several coffee books, referenced in newspaper and magazine articles, and by our server count, had been read well over 1.2 million times since its initial publication. For the launch of the new CoffeeGeek website in 2021, we decided it was time to give this list a full update, including new terms (like naked portafilter) that weren’t on the original glossary. We present it here.

For many people new to espresso, some of the terminology surrounding this brewing method can be confusing and in some cases, very “inside baseball”.

Terminology exists in all things. Camera guys talk about ISO and f stops. Espresso people talk about BAR, shot times, ristrettos, etc etc, and it gets quite confusing for the newbie.

Because of this, we’re presenting this one-stop article that attempts to detail all the major terms used in espresso. It has gotten a full update, and we’ll be adding photographs as this continues to get a full update. Eventually, it will be part of CoffeeGeek’s forthcoming Espresso Guide Masterclass.

The Espresso Glossary

In the past few decades the home espresso situation has radically changed. 20 years ago, your best bet for home espresso was from a steam toy Krups or Braun machine, or an “exotic” $400 machine from one of the Italian manufacturers. Today, there is an absolute wealth and breadth of home espresso machines that range from very capable $300 models to $4,500 models that rival the technologies and abilities found in commercial machines.

Along with quality espresso machines, we now have access to a good range of quality grinders. It’s hard to believe this today, but 20 years ago, it was quite difficult to get a grinder well suited for espresso, and if you did, it was usually a machine designed for commercial use.

Then there’s the Internet, and more specifically, the world of YouTube influencers. These avenues are great for quick learning and especially if you prefer a visual walk through of how to do something in the world of coffee or espresso, but I often feel these things can be fleeting if you don’t actually know the background, history, and development of techniques that got us to the point where some guy on YouTube can show a 3 minute video of prepping an espresso shot and have it pour out nicely.

Sometimes, having more information and background helps you be better at something. And that is why this Glossary exists.

Espresso Machine Terminology

A lot of this glossary is taken up by espresso machine terminology. Terms like grouphead, gasket, BAR, extraction time, etc. It can be very confusing for the first time consumer, so we try to separate the fluff and marketing stuff from the actual information that’s important to know about when it comes to espresso machines.

With that said, let’s get into the Glossary. After every major letter section, you’ll see the following , which is a quick way to jump up or down within this guide. This will become even more handy when we add visuals to the guide.

Numbers

3 Way Solenoid: See Pressure Release System.

1:1.5 Ratio: Often considered the Ristretto ratio of espresso brewing. It refers to the amount of coffee used versus the brewed output (in weight) of espresso. For the 1:1.5 ratio, if you use 18g of coffee, your output target is 27g of liquid.

1:2 Ratio: Often considered the “golden ratio” for espresso brewing, it refers to the amount of coffee used versus the brewed output (in weight) of espresso. For the 1:2 ratio, this would mean if you brewed with 18g of coffee, your output target in the cup is 36g of liquid.

1:3 Ratio: Often considered the “Italian Ratio” for espresso brewing, it refers to the amount of coffee used versus the brewed output (in weight) of espresso. For the 1:3 ratio, this would mean if you brewed with 18g of coffee, your output target in the cup is 54g of liquid.

Letter A

Americano: (also caffe americano); an espresso based beverage that usually features a ratio of 1:2 for espresso to hot water. We have a full How To on making an americano.

Auto Frother: refers to a part of a machine designed to automatically froth milk, and can come in different engineering styles. Older automatic frothers would draw milk through a tube and mix it with steam that could be adjusted to provide hotter or colder steamed and frothed milk. Newer systems, like those found on the Breville Oracle and Bambino Plus machines use higher end technology to control steam and air flow, and temperature sensors to deliver specific heated milk temperatures in a steaming pitcher.

Automatic: can refer to a class of espresso machines that require you to grind, dose and tamp your coffee into a portafilter, but the machine brews for a predetermined (and optionally, programmable) volume and provides the required pressure automatically. The Breville Infuser is one example of an automatic espresso machine.

Letter B

Backflush: term (including backflushing) used to describe a cleaning process used on espresso machines, that is automatic on some, and a manual process on others. To manually do this, it usually involves using a blind filter to not allow any water to escape the brewgroup while the pump is activated; once the machine’s pump is turned off, water is forced through the machine’s pressure relief system to flush out old solids and other build up.

BAR: Pressure rating used on most pump driven espresso machines. 9 BAR, the typical accepted pressure for brewing espresso is 8.8 atmospheres of pressure or 130 pounds per square inch. Almost every consumer espresso machine with a vibratory or rotary pump is capable of producing this pressure consistently.

Barista: is the Italian term for the person who operates the espresso brewing equipment at a cafè or coffee house. When you become proficient at brewing your own espresso drinks, you might regard yourself as an accomplished barista.

Blind Filter: A metal basket that fits into a portafilter, but has no holes or perforations, just a solid metal plate. Its purpose is to force pressurized water to backflush through the machine’s pressure relief valves and system, cleaning the espresso machine.

Boiler: the main heating unit for water in an espresso machine. Made of brass, stainless steel, copper or aluminum, the boiler is one of the most important components of the machine.

Brew Group: the area of the machine that contains the grouphead and portafilter and filter baskets. Some brew groups (see E61) are actively heated, some are passively heated by the boiler through metal on metal contact. The entire brew group should be sufficiently heated in order to brew a proper espresso. The term brew group also refers to the removable assembly found inside super automatic espresso machines.

Brew Temperature: is often referred to in espresso machines. Opinions do vary, but the general consensus is that espresso should be brewed with water that is between 190 and 205F (at sea level) in order to obtain optimal extraction.

Brew Time: is used as one of the indicators to diagnose espresso shots. Brew time is calculated from the moment the pump switch is activated, until the pump switch is turned off, both on machines with preinfusion modes, and those without. In some cases, trainers and other espresso professionals prefer to separate preinfusion time from brewing time. Historically, the guidelines for a proper brewed espresso on a non-preinfusion machine was between 25 and 30 seconds. More recently, the acceptable range is 25-45 seconds, with or without preinfusion time.

Burr Grinder: is the recommended type of grinder for proper espresso making. A burr grinder features two disks, one stationary, one rotating, which slice away portions of a coffee bean into very fine particles.

Letter C

Café Crème: (also a Cafe Suisse) an espresso type beverage brewed in a similar manner to normal espresso. However, where espresso is brewed at a pace delivering roughly 1.5 ounces over 25 seconds (or 3 ounces for a double in 25 seconds), café crème is brewed at a faster pace – as much as 5 ounces or more in 25 to 30 seconds. This is achieved by altering the grind of the coffee to allow for more flow through into the cup. Under no load, a properly running pump driven espresso machine should deliver between 2.5 to 3.5 fluid ounces every 10 seconds. By altering the coarseness of your grind, you alter the flow rate of your brewed beverage. We have a full How To on the Café Crème.

Cafe Suisse: See Café Crème.

Caffe Americano: See Americano.

Caffe Latte: (or café latte) a beverage that is based on espresso (or moka coffee) combined with steamed milk. This is a very popular beverage in the USA. The latte also serves as the basis for other drinks like flavoured lattes, where a sweet flavoured syrup is added. Traditionally, a latte is topped with foamed milk. We have a full How To on the Caffe Latte.

Caffe Mocha (or Mocha): similar to a Caffe Latte, the mocha includes chocolate syrup or powder added to the beverage which results in a coffee and chocolate taste combination. Chocolate milk is sometimes used but is not recommended because flavorings achieve better results and the sugar in chocolate milk tends to crystallize on the steaming wand, making clean up a bit more difficult. Mochas are often topped with whipped cream.

Cappuccino: is a drink traditional with a 1:1:1 ratio of espresso to steamed milk, to frothed milk. A traditional cappuccino is a 135ml (4.5fl.oz) beverage, served in a 150ml (5fl.oz) cappuccino cup. Optionally can be topped with cinnamon or other spices or powdered chocolate. We have a How To on making a cappuccino.

CC: Many espresso machines are made in Europe, and the unit of measurement often used for boiler sizes is expressed in cc, which is the same as ml or milliliter. 100 cc is 3.38 US fluid ounces.

Chopped Portafilter: (also known as a naked or nude portafilter), invented by two baristas from Zoka Coffee around 2004, it is a portafilter with the bottom solid portion removed or cut out, to expose the bottom of the interior filter basket to the open. It has proven to be an excellent tool in diagnosing faulty espresso preparation techniques. There is some debate about whether or not the resulting shots are better or worse, using a chopped portafilter.

Coda di topo: Italian for “mouse tail” which refers to the shape and pour of the streams of espresso as they leave the portafilter spouts during a brew. Often used as a judging characteristic of a good pour, because if the bed of coffee is properly ground, distributed and packed, and the water flow is even, there’s almost no turbulence coming out of the bottom of the filter basket, which results in a nice straight “coda di topo”.

Coffee Bed: see Co ffee Pack.

Coffee Pack: is one of the terms used to describe the tamped volume of grinds in a filter basket prior to brewing a shot of espresso.

Commercial: when used to describe an espresso machine, commercial refers to a machine that can be used in a commercial environment such as a cafe or restaurant where high volume output is required and durability of parts is important. Commercial grade machines can brew shot after shot of espresso, all day long.

Consumer: when used to describe an espresso machine, refers to a machine primarily designed to be used in a home under light to medium use.

Control Panel: s the area of the espresso machine where you control most or all of the machine’s functions. There is usually a power switch, a brewing control switch, and a steam control. On some machines there is also a hot water dispensing control. There are different variants as well: some control panels use rocker type switches and control knobs; some use push button switches; and other types use pressure sensitive switches.

Crema Enhancer: an engineered device or design for producing fool proof “crema” (not authentic) when brewing espresso. See also Pressurized Portafilter or Pressurized Filter. Crema Enhancers do not produce crema the same way that traditional brewing does, and the results are often poor in taste.

Crema: is one of the sure signs of a properly brewed shot of espresso (in non crema-enhancing machines) and is created by the dispersion of gases – air and carbon dioxide – in liquid at a high pressure. The liquid contains emulsified oils, and forms a dark golden brown layer resembling foam on top of an espresso shot.

Cup Tray: is the part of an espresso machine where you place your cup when you commence brewing a shot of espresso. The cup tray sits on (or is part of) the drip tray.

Cup Warmer: the part of an espresso machine that warms espresso cups. It is usually the top of the machine, sitting over the boiler itself (which is inside the machine). Not all espresso machines have cup warmers. Some have actively heated cup warmers (including the Solis SL-90). Cup warmers are beneficial because a small 1.5 ounce drink can lose its heat very fast if it is poured into a cold receptacle.

Letter D

Demitasse: the cup that holds a traditional shot of espresso is called a demitasse – the fancy word for the small 3 ounce (or smaller) cup. Demitasses can be made of ceramic, stainless steel, or glass, though porcelain is often the preferred material. The thicker the better, as they must retain heat well in that small 1.5 ounce beverage you craft.

Direct Lever: a type of lever controlled, piston driven espresso machine where the force the user applies against the lever is directly translated into the pressure applied to the water pushing through a bed of coffee. La Pavoni machines (reviewed here) are typically direct lever espresso machines. On the manual front, machines like the Flair Espresso machine (reviewed here) and the Cafelat Robot (reviewed here) are also direct lever espresso machines.

Dispersion Screen: This is part of the Brew Group and is an essential part of an espresso machine. It serves the purpose of properly dispensing brewing water over a wide pattern into the portafilter and filter basket, ensuring the entire coffee bed is saturated with water at the same time.

Distribution Technique: A style or technique designed to settle the grounds of coffee in an even fashion inside a portafilter filter basket, in order to ensure a more complete and even extraction from the ground coffee. See WDT for one such method.

Distribution Tool: Specifically designed tools to help level out a bed of coffee in a portafilter’s filter basket. Sometimes they are in form of a piston or tamper shape, other times they can be precision cut metal or plastic shapes. In the tamper style, you have tools like the BT Wedge Distribution Tool. Precision cut tools include Breville’s Razor tool, or the Scottie Callaghan Dosing Tools.

Dosage: refers to the amount of ground coffee used to produce a shot of espresso. Historically espresso used a 7 gram dosage (a level tablespoon) of coffee to produce a 45ml (1.5fl.oz) beverage. The more recently accepted standard is 16-19g dosage to produce a 45-60ml (1.5-2fl.oz) double shot beverage.

Doser: found on many burr grinders, especially those designed to be used with espresso machines. A doser releases a measure of coffee grounds as you pull on a lever that is built into the side of the doser.

Double Basket: the most common type of filter basket used with espresso machines. A double basket can hold roughly 14 grams (or more) of coffee grounds. See Filter Basket for more details.

Double: refers to a specific way to order an espresso, or to the typical pour of an espresso. Since the double basket is most often used, a “double” is what is often poured. A traditional Italian style double is 60-85ml of espresso (2-3fl.oz) in total liquid volume. A traditional North American double is 40-60ml (1.3-2fl.oz). Can also refer to other brewed beverages, including a double Caffe Latte or a double Mocha.

Drip Tray: sits directly underneath the brew group and catches spillage from the brewing process. On machines equipped with a 3 way solenoid valve the drip tray is also used as the drainage area for the expulsion from the valve after a shot is completed. Drip trays can often be removed to empty or clean, and are made of plastic or metal.

Letter E

E-61 Group: is a specific grouphead design found on many commercial machines and some consumer or prosumer espresso machines. The E-61 grouphead is actively heated by circulating water drawn off the boiler. This aids in the temperature stability of the machine. The group also allows for manual (or automatic) control of preinfusion, or passive water access to the Coffee Puck.

Espresso: the coffee beverage produced by a pump or lever espresso machine. This Italian word describes a beverage made from 7 grams (+/- 2 grams) of finely ground coffee, producing 30-45ml (1-1.5fl.oz) of extracted beverage using appximately 9 bar (135psi) of brewing pressure at brewing temperatures of between 194 and 204 degrees Fahrenheit, over a period of 25 seconds (+/- 5 seconds) of brew time. We have a complete How To on making an espresso.

Extraction Time: See Brew Time

Extraction: is the act of forcing hot water from the boiler though ground coffee, which in turn “extracts” flavors, oils, colloids, lipids and other elements that turn water into brewed coffee or espresso.

Letter F

Filter Basket: is a metal, flat bottomed “bowl” shaped insert that fits inside a portafilter. The filter basket holds your bed of ground coffee and has a multitude of tiny holes in the bottom to allow the extracted beverage to seep through and pour into a demitasse cup or other receptacle. Most espresso machines include two filter baskets, a single basket and a double basket, though some machines feature convertible baskets that allow either a single or double shot of espresso to be produced from the same basket.

Flushing: a term used to stabilize or reduce the temperature on single boiler espresso machines, especially after steaming milk. Typically, the water in the boiler is super heated after steaming milk, and needs to be “flushed out” of the machine to bring the temperatures back to brewing temperature.

Foam: See Froth.

Froth Aider: (also foam enhancer, pannerello, cappucinatore) is a device that facilitates the production of milk froth and using the steaming device built into most espresso machines. These come in a variety of shapes, sizes and functionality: some are straightforward steam tube enhancements that can draw air through pin sized holes near the top, and mix it with steam automatically to “froth” milk. Others can actually draw milk through a tube, mix it with air and steam to pour out a ready made froth/steamed milk mixture into a cup. Still others use electro-mechanically controlled air vents to adjust the volume of foam produced based on user settings (like the Breville Oracle espresso machines).

Froth: is produced when milk is steamed with an espresso machine’s steaming wand. Air must be introduced into this act to properly froth milk, and this is done by hoving the steam tip right near the surface of the milk: the steam agitates and heats the milk but also draws air at high velocity into the milk, thus creating the foam, or froth. True milk froth should be pourable, not shapeable – you should be able to pour steamed milk and froth, not spoon it out in clumps.

Frothing Knob: See Steam Knob.

Frothing Pitcher: is a 350ml-750ml (12-24fl.oz) pitcher with a handle, pour spout, and is usually made of high quality stainless steel. It is designed to be used as the receptacle for holding milk while steaming and frothing. They are commonly used by baristas to steam cold milk for any milk-based espresso drinks. Also known as a milk warmer or steaming pitcher.

Frothing Tip: refers to the perforated tip on a steaming wand. These can have between one and four holes, and the holes can be either angled to the side or pointing straight down. They allow the steam from the espresso machine to be forced into tiny jets which agitate and heat milk at a great pace and also facilitate proper frothing when used to introduce air into the milk.

Letter G

Gasket: a catch all term to describe various o-rings and/or seals used on an espresso machine, including, but not limited to, the sealing gasket used inside an espresso machine’s grouphead.

Gicleur Valve: most modern espresso machines are fitted with this kind of valve, also known as a jet or choke nozzle. The nozzle’s purpose is to control and manage pressurized water to provide even (and in some cases, controllable) build up of pressure in the grouphead.

God Shot: A term coined in the newsgroup alt.coffee and popular on the CoffeeGeek website and in some mainstream press, used to describe a shot of espresso that is the most perfect shot you have ever achieved. A “god shot” is a shot so good, it must have been blessed by God. This type of shot can improve as your level of skill improves. A “god shot” from three years ago may be your average shot today.

Grinds Bin: The container where the ground coffee is output to on a coffee grinder. Refer to our Grinder section for more information.

Group: See Brew Group.

Grouphead: is the part of the brew group where brewing water enters (usually through a gicleur valve), and contains the locking connector for the portafilter and the dispersion screen. These are usually made out of brass, but sometimes other materials such as stainless steel or aluminum are used. The grouphead is an integral part of the espresso machine and is also part of maintaining temperature stability in most machines, essential for producing a good shot of espresso.

Letter H

Heat Exchanger: a feature found on many commercial machines and an increasing number of consumer machines, this is a system where a boiler — typically used for steam — has an internal piping system that draws cold water through it, thereby flash heating it up to espresso brewing water temperatures nearly instantly. More recently, heat exchangers have seen a new role on espresso machines: not to bring brewing water up to brewing temperatures, but to pre-heat the brewing water before it arrives in the brew boiler or heating apparatus inside an espresso machine. This allows the power draw of the espresso machine and its two boilers to be much better managed, and allows for much more precise control over brewing water temperatures for espresso production.

Heat Up Time: refers to how long an espresso machine requires before it is up to normal operating temperatures once you switch the machine on. In smaller consumer machines, the heat up time can be as little as two or three minutes. In prosumer and commercial machines, it can be as long as 30 minutes. These machines require a longer time because they have bigger boilers and more metal components to properly heat up. While the longer heat up times are unfortunate, they do have a very good purpose – longer heat up times usually mean better temperature stability and recovery times in the espresso machine, meaning they produce more consistent shots of espresso.

Hopper: refers to the part of a coffee grinder that holds whole coffee beans.

Housing: this is the main body and shell of an espresso machine. The “housing” holds all the internal components, and supports the main exterior parts. Usually made of plastic or metals such as iron, brass, steel or aluminum.

Letters I J K

Knockbox: a bin, box or other container, with a rubber or wooden bar across a wide opening. Used to dispense of the spent puck after brewing an espresso shot. The portafilter is rapped (or knocked) against the bar, and the spent puck of coffee grinds is “knocked” out into the bin.

Letter L

Latte: See Caffe Latte.

Lever: refers either to a specific type of espresso machine or a part on an espresso machine. Lever espresso machines come in two technologies: a direct lever version, or a spring piston lever version. In both cases, the machines are considered manual espresso machines, or manual brewing devices, because there is no active electro-mechanical pump providing the brewing pressure. On direct lever machines, the operator is the “pump”, applying direct pressure. On spring piston machines, the operator uses the lever to cock or load up an internal spring, compressing it. Once the lever is released, the spring uncocks (or decompresses), applying pressure to the brewing water.

Lungo: an espresso shot that is purposely poured “long” or for extra volume. Where a normal single espresso shot is approximately 1.5 ounces of brew, the lungo may be 2 or 3 ounces per shot. We have a How To on making a Lungo.

Letters M N

Macchiato: traditionally in Italy, a shot of espresso marked with a small dollop of milk foam. In North America, traditionally a 1:.5:.5 ratio drink of espresso to steamed milk to foamed milk. We have a How To on making both types of Macchiato.

Manual: can refer to a class of espresso machines where the operator or barista manually provides the pressure needed to brew a proper shot of espresso. Lever or Spring Piston espresso machines are manual espresso brewers. The Pavoni Professional is an example of a manual machine.

Manual can also refer to the instructions that accompany a machine. CoffeeGeek recommends you always read the product manuals that accompany these complicated machines. See RTFM.

Mocha: See Caff e Mocha.

Moka Pot: an manual method of making a strong coffee. The moka pot is often referred to as an “espresso machine” but it is not one, using today’s modern definition of what espresso is supposed to be. A moka pot is usually used on the stovetop (though self-contained, self-powered devices exist), and brews by forcing hot water through a bed of coffee using the power and pressure of steam. Most early “espresso” machines prior to the advent of pump or piston driven machines worked on the same principle of using steam to force water at slightly higher pressures than normal. A typical moka pot brews using 1.5 atmospheres of pressure (modern espresso machines use roughly 9 atmospheres, or BARs).

Naked Portafilter: See Chopped Portafilter.

Letter O

Over Extracted: term used to describe coffee or espresso that has had brew water exposed to ground coffee for too long. Over extracted espresso and coffee can taste bitter or burnt.

Letter P

PID: an acronym for Proportional, Integral, Derivative, which is a set of equations and algorithms, long used in industrial and scientific labs for specific control and curving of temperatures. The name also applies to the electronic control boxes that manage these algorithms. The PID was introduced to the espresso world around 2000 by Andy Schecter and Greg Scace who both installed a PID controller on their home Rancilio Silvia machines to make the machine operate with much more precise brewing temperatures. It has since been used on a wide variety of home and commercial espresso machines to provide brewing temperatures accurate down to 0.1C.

Piston: in espresso terminology, a piston is the element in which you force water at high pressure through a finely ground bed of coffee. The piston usually operates with a lever or spring to apply the pressure.

Plumbed In: Most commercial espresso machines and many “prosumer” level espresso machines can be attached to the main water line in your house, giving constant water delivery to the machine. These machines are referred to as “plumbed in”. These machines can also be hooked up to alternative water supplies, including water bottles, but need a helper pump to provide the 50-75 PSI of water pressure your home plumbing usually provides to your faucets.

Pod Portafilter: a portafilter specifically designed to use espresso pods. In many cases, these portafilters are designed according to E.S.E. specifications. (Easy Serving Espresso).

Pod: a self-contained, pre ground, pre pressed puck of ground coffee. They are usually inside a perforated paper filter, and in many cases are sold individually wrapped to maintain freshness. Illy helped to create this system, and many pods are based on E.S.E. specifications (Easy Serving Espresso).

Portafilter Sneeze: on pump and piston espresso machines that do not feature a pressure release system, removing the portafilter too soon after brewing a shot can result in the instant release of pressure in the brewhead, causing extremely hot and wet coffee grinds to spray and cause potential injury. When you complete the brewing of an espresso shot, some of the 135 PSI of pressure remains in the portafilter, and normally takes 30 seconds to a minute or longer to bleed off, allowing safe removal of the portafilter.

Portafilter: (also known as a groupo) the device that holds a filter and finely ground coffee and facilitates quick attachment to an espresso machine. Portafilters almost always feature a handle for easy handling, and spouts underneath to allow your espresso to pour into cups. On better espresso machines, they are made of copper or brass, and are coated with chrome. The handles are usually wood, bakelite, or plastic. On less expensive machines they can be aluminum, steel, or other metals and plastics.

Pre Infusion: the act of pre-wetting the bed of ground coffee inside an espresso machine at low or no pressure, before actually commencing the pressurized brew. Pre infusion is achieved in different ways on different machines. On lever machines, the pre infusion is controlled via the lever arm. Some machines run the pump for a few seconds, pause, and then continue to run. Other machines regulate the pump’s active pressure, running at a lower pressure for a preset time, then ramping up to full pressure for the remainder of the shot process. Still other machines, with E61 style groups, do a “natural” pre infusion style with a secondary chamber requiring a fill before the full pump pressure is applied to the bed of coffee.

Pressure Relief System: (also 3 way solenoid) on most commercial machines, prosumer machines, and many higher end consumer espresso machines, a 3 way valving system exists to immediately remove pressure from the portafilter once your espresso shot is completed. A check valve is electrically controlled: it is closed when the machine is not under operation; it opens a passage between the boiler and the grouphead and portafilter when you are brewing; and it opens a passage from the grouphead to your drip tray (or other “waste” area) once you end the brew. This system allows for quick successive brews, without any worry of a “portafilter sneeze” where the excessive pressure that remains inside a portafilter can spray hot, wet grounds all over should you remove the portafilter too soon after brewing a shot of espresso.

Pressurestats: on many prosumer and commercial espresso machines, the temperature of the boiler is maintained not with a thermostat control, but a pressure gauge control that activates the boiler’s heater once the measured pressure drops too low. It also shuts off the heater when the pressure reaches a certain point. Pressurestats are almost always found in heat exchanger espresso machines and in steam (not brew) boilers.

Pressure Profiling: Alternating, modifying, or otherwise controlling the pressure applied to a bed of coffee inside an espresso machine’s grouphead. On some machines this can be programmed for different stages of pressure application. Though this is a recent trend with pump driven commercial and consumer espresso machines, direct lever espresso machines always allowed the operator to manually control whatever pressure they wanted to brew the espresso under.

Pressurized Filter: on some espresso machines, a crema enhancing device is built into the actual filter basket, usually through the function of channeling all the brewed coffee through a solitary pin hole. This action creates a jet-like effect that boosts crema production, even in stale coffee or coarse ground coffee. The Solis machines use pressurized filters.

Pressurized Portafilter: on some espresso machines, a crema enhancing device is built into the portafilter. These portafilters use normal filter baskets, but the portafilter itself is designed to channel the brewed espresso through a tiny pinhole to create a jet-like effect which boosts crema production.

Prosumer: is a term that, when used in describing espresso equipment, implies machines that often incorporate commercial equipment materials or qualities. These are machines that could see light commercial usage.

Puck: is the term used often to describe the bed of coffee grounds after you have brewed a shot of espresso. Also called a spent puck.

Pull: a term used to describe brewing a shot of espresso. Comes from the action used to prepare espresso in the 1950s, 1960s, and beyond – pulling on a lever to cock a spring in a piston group on an espresso machine. Also Espresso Pull, Pull a Shot.

Pump: two primary ways to deliver water at pressures required for proper espresso brewing (135 PSI) are through the use of a rotary pump, or a vibratory pump. Most modern day semi automatic, automatic, and super automatic espresso machines use one of these two pump technologies. See also Rotary Pump and Vibratory Pump.

Letters Q R

Recovery Time: When brewing espresso shots in succession, the amount of time you have to wait until your espresso machine is ready to brew again is called “recovery time”. Machines with larger boilers, more powerful heating elements, or with heat exchanger systems often feature quicker recovery times than machines with small boilers.

Ristretto: literally, a “restricted” shot. Most double espresso shots are 45-60ml (1.5-2fl.oz) using 14 or more grams of coffee. A ristretto uses the same volume (or dose) of grinds, but the operator extracts only 25-35ml (.8-1.2fl.oz), or less of espresso in the normal brewing time of 25 to 30 seconds. A ristretto is a richer beverage, much more intense, but also much harder to brew properly. There is a fine balance between stalling an espresso machine and making a perfect ristretto. We have a How to on making a ristretto.

Rotary Pump: A rotary pump is often found on commercial machines, and requires water to be plumbed in. They use rapidly oscillating vanes inside a sealed container to push water at high pressures. Sometimes referred to as a volumetric pump, or by a trade name, Procon.

RTFM: an acronym for “read the fine (or another word) manual. It is advice that it is always wide to read the entire manual provided with an espresso machine.

Letter S

Semi-Auto: refers to a class of espresso machines where the pressure for the espresso shot is automatically controlled by the machine, as is the brewing temperature. The operator or barista controls the length of the brewing time manually. The Rancilio Silvia is an example of a semi-auto machine.

Shot: another term to describe a brewed espresso.

Single Basket: a filter basket designed for producing a normal single shot of espresso. This basket has a narrower bottom portion when compared to a double basket. This size of filter is rarely used, but included with most espresso machines.

Single: often refers to a single shot of espresso, brewed with a single basket, or splitting the output from a double basket shot into two cups (or two singles).

Spent Puck: see Puck.

Spout(s): refers to the exit area on a portafilter where the brewed espresso pours out. Portafilters can have one or two spouts, though most come standard with two spouts.

Spring Piston Lever: a type of lever controlled, piston driven espresso machine where the force the user applies on the lever compresses a spring inside a column; once the lever is released, the spring uncompresses and applies even (and declining) pressure to the water being pushed through a bed of coffee. Spring Piston Lever espresso machines are the earliest forms of “pressure profiling” technology in that they provide an even, yet gradual decline in brewing pressure as they uncompress.

SSR: which is an acronym for Solid State Relay, and it is technology often used in higher end commercial espresso machines (but also a growing number of consumer machines) for temperature control management in brew and steam boilers.

Stall: (also stalling) occurs when coffee is ground too fine and/or tamped too hard, and the espresso machine pump cannot produce enough pressure to force water past the coffee grounds. Most often occurs when attempting to brew a ristretto shot.

Steam Knob: Most consumer, prosumer, and commercial espresso machines use a manual valve control knob to release steam from the machine’s boiler or thermoblock. By controlling the knob, you can increase or decrease the amount of steam pressure released. Steam knobs are used to control the steam used to froth and steam milk.

Steam Pressure Espresso: This can refer to moka pots or “espresso machines” that rely on steam pressure solely to push water through a bed of coffee. Most of the typical $40 to $80 espresso machines you may see at department stores are steam pressure espresso makers. They are essentially self-contained, electric moka pots. Also called steam espresso.

Steam Valve: this is the valve you control with a steam knob, that allows steam to be released from an espresso machine’s internal boiler or thermoblock.

Steam Wand: is a visible, external pipe found on most espresso machines that is used to froth and steam milk, to provide hot water (on some machines), and heat espresso cups. Some also use the steam wand to heat water. It is controlled by a steam knob that opens and closes the steam valve inside the machine.

Super Auto: see Super automatic.

Super automatic: traditionally, a class of espresso machine that can grind, dose, tamp, brew, and eject a spent puck, all with one push of a button. Some commercial super automatics can also steam milk automatically, depending on your brew selection. The Jura Ena Series is an example of a straditonal super auto. More recently, Breville upended this category with the release of their Oracle line of machines, which provide almost every feature a super automatic does, but by using a more traditional machine design style.

Letter T

Tall: another word used to describe a large volume beverage.

Tamp: (also tamping) the act of pressing and compacting a bed of loose, finely ground coffee, in preparation for brewing espresso. Different machines require different tamping methods. Steam powered espresso requires a leveling tamp, where piston lever, spring lever, and pump espresso requires a more compacting action. Some prefer a heavy tamping action (using 25 or more pounds of pressure), others prefer a light tamping action (less than 15 pounds of pressure exerted).

Tamper: the device used to tamp a bed of loose, finely ground coffee in a portafilter, in preparation for brewing espresso. Most espresso machines include a plastic tamper as an accessory, and after market tampers can be bought. They are measured in millimeter sizes, corresponding with the filter basket internal diameter of your espresso machine. Most commercial, prosumer, and high end consumer espresso machines use a 58mm tamper; other common sizes are 49mm, 53mm, and 57mm.

Temperature Profiling: A recent development in espresso machine brewing, pioneered by Rancilio with their XCelsius commercial espresso machines, the idea behind it is control the temperature of the pressurized brewing water at every stage of the brewing process in espresso. There is a well developed theory that the longer you brew coffee, the better it benefits from a reduced temperature later in the brewing process.

Temperature Stability: is the term used to describe how even an espresso machine can maintain its temperature throughout the machine, from the boiler to the grouphead. Prosumer and Commercial grade espresso machines feature a greater control and evenness of temperature stability, even when brewing consecutive shots of espresso.

Temperature Surfing: on most single boiler espresso machines, a pressurestat or other mechanical thermostat controls the on or off state of the heating element in the boiler. There is a float in temperatures through this action, usually about 10-20F. As an example, a boiler’s thermostat may engage the heating element when it reads below 190F (but these thermostats aren’t very accurate, so it could be 185F or 195F), and will cut off the heating element when it reads around 205F or 210F (and again, due to the lack of accuracy in thermostats, it could be +/- 5F). Because espresso’s optimal brewing range is 197-202F, baristas will choose their time within the heating element cycle of on and off to start brewing a shot, or induce cold water into the boiler for a set period of time (usually under 3 seconds) right after the heating element shuts off, to cool the boiler down 5-10F to brew a shot. All of this comes with experience and/or the use of accurate thermometers reading the water temperature at the grouphead for reference points. In addition, tricks such as using a cold portafilter and extensive group flushing before a shot can be used to “temperature surf” a machine brewing too hot (or cold).

Thermoblock: in some espresso machines, the heating system is shaped similar to that of a car radiator, a series of heated metal coils or channels which water must pass through and become progressively hotter as it reaches the boiler.

Thermometer: a device used to measure temperatures. In coffee and espresso, it can refer to a device with a circular top and long needle to measure milk steam temperatures, coffee roasting temperatures, or other temperatures.

Thermostats: on most consumer, single boiler espresso machines, the temperature of the boiler is controlled via a temperature measuring device called a thermostat. The thermostat (usually) is electrically, mechanically, or electronically controlled, and can activate and deactivate a heating element, depending on what temperature it measures.

Tiger Striping: A term first used on the newsgroup alt.coffee and the CoffeeGeek forums, it is used to describe the phenomenon of different coloured stripes of brown witnessed in the streams of espresso pouring from a portafilter’s spouts while brewing. It is even more visible in a chopped or naked portafilter shot. It usually happens and is an indicator of the use of good brewing techniques, fresh roasted, fresh ground coffee, and good brewing temperatures.

Letters U V

Under Extracted: in coffee and espresso terminology, this refers to a bed of coffee that has not been exposed to enough passing water. The resulting brew is often weak and thin bodied.

Vibratory Pump: is often found on consumer espresso machines, and can be fed water from a reservoir. Vibratory pumps use a diaphragm that expands and contracts at great rates, creating a rapid pulse of high pressure water.

Volumetric Pump: See Rotary Pump.

Letters W X Y Z

Water Filter: Many coffee and espresso machines feature a built in water filtration system. Some are very rudimentary, consisting of a mesh or metal filter which water must flow through before reaching the boiler or heating element. Other systems are more complex, including charcoal or other filter medium systems that remove impurities, chlorine, and other trace elements from water.

Water Reservoir: Most consumer and many prosumer espresso machines, as well as most coffee brewers feature a built in tank or container that holds water that is used by the machine to brew coffee or espresso. The water reservoir also supplies water to steaming devices on machines that include a separate steam ability.

Water Softener: some espresso machines and coffee brewers feature advanced filtering systems that can soften water, helping to prevent limescale (or other) buildup in the boiler or heating element area.

WDT: Acronym for the Weiss Distribution Technique, self-named by John Weiss on the Home-Barista website when he first outlined it. The technique corrects error s in grinders that output their grind in clumpy, uneven groups. It involves stirring the bed of coffee with a thin object, like a thick needle, to break up the clumpy coffee and even out the distribution. To prevent grinds from spilling out of the portafilter, some have McGyver’ed up small yogurt cups or similar plastic containers to wedge into the filter basket during the stirring.

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photo credits:

All photos by Mark Prince and CoffeeGeek

Columnist

Mark Prince

Mark has certified as a Canadian, USA, and World Barista Championship Judge in both sensory and technical fields, as well as working as an instructor in coffee and espresso training. He started CoffeeGeek in 2001.