Coffee terms explained

A bean-to-cup machine takes the whole process off your hands: it grinds, tamps, brews and drops the puck into a container you empty now and then. You never touch the coffee.

That is the reason to buy one and equally the reason not to. You have little influence over the result, and what comes out is consistently good rather than occasionally exceptional.

The part that decides whether you still like it in three years is the milk system, not the grinder. Pipework you have to rinse daily becomes a chore; a jug or a two-part system that goes in the dishwasher does not.

See also: Portafilter machine, Brew group

On a portafilter machine you do every step. You grind, weigh, tamp and lock the portafilter into the group head. The machine only supplies water at pressure and temperature.

The result therefore depends on you. That is a pleasure if you enjoy it, and a daily irritation if at seven in the morning you only want coffee.

Reckon on two weeks before you pull a shot reliably well, and on a separate grinder if the machine has none. A portafilter machine fed pre-ground coffee from a bag rarely beats a good bean-to-cup machine.

See also: Bean-to-cup machine, Portafilter, Tamping

Espresso is not a kind of bean but a method: hot water is forced under pressure through a compressed bed of ground coffee. A double shot is roughly 16 to 20 grams of coffee yielding 40 to 60 millilitres in about 25 to 30 seconds.

Everything on this site is about that method. A machine that does it well handles cappuccino and latte macchiato as a matter of course. That is the same espresso with milk added.

The ratio between dry coffee and what comes out is called the brew ratio. A common espresso sits near 1 to 2: 18 grams in, 36 grams out. That is the number that lets you reproduce someone else’s recipe on any machine.

See also: Extraction, Crema, Ristretto and lungo

Too short or too coarse and you pull too little: the coffee tastes sour and thin. Too long or too fine and you pull too much: bitter and drying. Between the two sits a window a few seconds wide.

Nearly every setting on a machine (grind, dose, temperature, pressure) exists so you can hit that window.

Change one thing at a time and taste in between. Sour and thin means coarser or shorter; bitter and drying means finer or longer. That sounds simple and is the whole craft, because at first both extremes just taste like "coffee".

See also: Grind size, Channeling, Pre-infusion

Almost every machine here quotes 15 or 19 bar. That is what the pump can deliver at most, not what reaches the coffee. The usual pressure for espresso is about 9 bar, and an over-pressure valve holds it there.

More bar therefore does not mean a better machine. It is a number that looks good on a box.

A pressure gauge on the machine reads the pressure in the system, not in the coffee bed. It is useful as a sign there is resistance, but a needle in the green is no proof the shot is running well. Time and yield tell you that.

See also: Over-pressure valve (OPV), Extraction

The valve that separates what the pump can do from what the coffee gets. Without it, 15 bar would break the coffee bed open and the water would run past it rather than through it.

On some machines the valve is adjustable. On most in this range it is not, which for most people is fine.

Some owners have the valve set down to 9 bar. That is a modification that can affect the warranty, and the effect is smaller than a good grinder: most shots that run badly run badly because of the grind, not the pressure.

See also: Pump pressure and bar, Channeling

A few seconds of water at low pressure lets the grounds swell and close up before full pressure arrives. The water then finds it harder to take a shortcut.

The difference shows most with lighter roasts and fine grinds. Machines also call it low pressure pre-infusion.

Note the difference between real pre-infusion and a programmed pause. Machines whose pump can run at low pressure do the first; machines that briefly switch the pump off do the second, and that only works if the line is already pressurised.

See also: Channeling, Extraction

Crema forms because carbon dioxide still trapped in the bean is emulsified into the coffee under pressure. Fresh beans give more of it than old ones.

It is an indication, not a seal of quality. A machine with a pressurised basket can whip thick crema out of poor coffee, and excellent light-roast coffee can give very little.

Freshly roasted beans give off so much gas that a shot from a just-roasted bag can foam and run unevenly. Rest beans a week to ten days past the roast date; after that they are at their best for two to three weeks.

See also: Filter basket, Espresso

On a bean-to-cup machine the brew group is a unit that compresses the coffee, pushes water through it and ejects the puck. On Philips, Siemens and Melitta you can take it out and rinse it; on Jura and De’Longhi it is partly fixed and the machine cleans it itself.

Removable is easier to maintain. It is no guarantee of a longer life, but it does make visible how dirty things get inside.

Removable or not also decides what a repair costs. A removable brew group is a part you order and swap yourself; a fixed one needs a service visit, and on a five-year-old machine that is often the moment people give up on it.

See also: Bean-to-cup machine, Descaling

The size is quoted in millimetres and decides which baskets and tampers fit. Every Sage machine here uses 54 mm; heavier commercial machines usually use 58 mm.

Heavier and thicker is generally better, because the mass holds temperature during the shot.

A heavier portafilter is also slower to warm. Leave it locked in while the machine comes up to temperature and run water through before the first shot. A cold one costs you ten degrees in the cup.

See also: Filter basket, Tamping, Portafilter machine

A single wall basket makes the result depend entirely on your grind and dose. A dual wall basket has a small hole that builds artificial back-pressure, so even pre-ground coffee produces crema.

Sage ships both. Start with dual wall if you have no grinder yet, and switch once you grind fresh.

The basket also decides the dose. Filling an 18-gram basket with 14 grams leaves the bed too low and the shot runs too fast; the size on the packaging is not a suggestion but the recipe.

See also: Crema, Grind size

Sage specifies 10 to 15 kilos of pressure in its manuals. More important than the force is that it is level: a sloped bed lets water through faster on one side.

The Barista Express Impress takes this step over with a lever, automating precisely the part where most people make the difference.

A tamper that does not fit the basket exactly leaves a ring of coffee uncompressed, and that ring is precisely where the water goes. So check the millimetre size of your portafilter, not what happened to be in the box.

See also: Channeling, Portafilter

If the bed is unevenly compressed or cracked, the water takes the path of least resistance. That part of the coffee is over-extracted and the rest under, and you taste both at once.

Sloped tamping, too coarse a grind and an overfull basket are the usual causes. Pre-infusion helps, but will not rescue a badly filled bed.

You can see it happening: a stream that spits, splits, or comes out of one side of the spout instead of as two even ribbons. With a bottomless portafilter you see it immediately, which is why people buy them.

See also: Tamping, Pre-infusion, Extraction

A ristretto is the same dose with less water: shorter, thicker, sweeter. A lungo runs longer: more volume, and past a point the bitter compounds you would rather leave behind.

On a bean-to-cup machine these are buttons. On a portafilter machine it is simply when you stop.

A bean-to-cup machine programmes this as volume, not as a ratio. Turn the dial to a bigger cup without raising the dose and you dilute the espresso rather than enlarging it, which is why the big button often tastes weaker.

See also: Espresso, Extraction

Finer means more resistance, so a slower flow and a stronger extraction. Coarser does the opposite. It is the first thing to change when a shot runs too fast or too slow.

Change one thing at a time. Adjust grind and dose together and you will not know afterwards which made the difference.

On a bean-to-cup machine, only adjust the grind while the grinder is running. Adjusting it stationary can damage the burrs; every manual says so and it is overlooked with great regularity.

See also: Grind settings, Extraction, Channeling

More settings means smaller steps between too fast and too slow. The Sage Barista Express has 16, the Impress 25 and the Barista Pro 30; the Philips bean-to-cup machines have 12.

On a bean-to-cup machine the count matters less, because the machine manages dose and flow itself. On a portafilter machine it is exactly where you notice the difference.

The steps are not equally sized everywhere. Thirty settings across a narrow range give finer control than thirty across a range that also has to serve filter coffee, so the number alone says less than it appears to.

See also: Grind size, Burrs

Burrs break the bean between two toothed surfaces, producing a more even grind than a blade grinder, which smashes it. Sage and Melitta state conical steel burrs, Philips, Saeco and Siemens ceramic ones; the other makers do not say.

Ceramic wears more slowly and stays cooler; steel is sharper and grinds faster. The difference in the cup is small next to the difference between fresh and pre-ground.

Burrs wear. In daily home use a set lasts years, but blunter burrs mean slower flow at the same setting. If after some years you keep having to go coarser, it is not the beans that changed.

See also: Grind size, Grind settings

A metal block with a channel through it. Water is heated as it passes, so the machine is ready in tens of seconds rather than minutes.

The trade-off is that little hot water is held in reserve: brewing and steaming back to back means waiting. Nearly every entry-level and mid-range machine works this way.

Flush before the first cup. The water standing in the block is not at temperature and has sometimes been tasting metal for hours; a five-second purge is the difference between the first and second cup.

See also: ThermoJet, Thermocoil, Boiler and dual boiler

Sage uses this name in its manuals for the Bambino and the Barista Pro. It is a flow-through system like a thermoblock, built to reach temperature in seconds.

We keep the maker’s own word rather than equating it with a thermoblock, because that would be a judgement Sage does not make.

The speed mostly changes your habit. A machine ready in three seconds gets switched on when you want coffee; a twenty-minute machine gets switched on at the start of the morning and left, with the electricity use that implies.

See also: Thermoblock, Thermocoil

A heating element cast into a water-carrying block. Sage calls it this in the manuals for the Barista Express, the Impress and the Touch.

In practice the difference from ThermoJet is mostly heat-up time, not the cup that comes out.

Because the element is cast into the block, little water is held. Making two cappuccinos back to back therefore means waiting between brewing and steaming, and that is exactly where a dual boiler differs.

See also: Thermoblock, ThermoJet

A boiler holds water at temperature rather than heating it on the way through. That costs heat-up time and buys stability across longer sessions.

With two boilers a machine can sit at brew temperature and steam temperature at the same time. No machine in this range has that; it starts above it. With one boiler, as on the Gaggia Classic Evo Pro, you wait between brewing and steaming while it reaches the other temperature.

A boiler also costs power to keep warm. A machine left on all morning uses noticeably more than a flow-through system that only heats on demand. Over a year that adds up beyond what the purchase price suggests.

See also: Thermoblock, Steam wand

A wand that blows steam into the milk. You decide how much air goes in and when to stop, and that is exactly the difference between microfoam and bath foam.

It takes practice, a week or two, and then gives a result no automatic system in this price range matches.

Purge the wand before and after. Beforehand you blow out condensed water that would otherwise thin your milk; afterwards you stop milk drying inside the wand, which is the most common reason a steam wand blocks.

See also: Microfoam, Automatic milk system

Well-textured milk is glossy and liquid, like wet paint, and pours into the cup rather than sitting on top of it. Coarse bubbles float and collapse within a minute.

Whole milk is the easiest to texture; plant milks need a barista version made for it.

Work with cold milk and a cold jug, and stop around 60 to 65 °C. If the jug gets too hot to hold, you have gone too far. Above 70 °C the foam collapses and the milk tastes boiled.

See also: Steam wand

A tube into a milk carton, or a jug you clip on. One button produces a cappuccino without you touching anything.

The part that decides whether you still like the machine in three years is how easily this cleans. Philips’ LatteGo is two parts with no tubes; systems with pipework need a daily rinse cycle.

Note where the milk sits in between. Systems with a separate jug go in the fridge; systems with a tube into a carton need the carton put back and the tube rinsed, and that is the step people skip.

See also: Steam wand, Brew group

Scale deposits where water is heated and slowly closes the flow down. Every machine here asks for it itself, based on the number of brews and the water hardness you set.

Ignoring it is the most common way to kill a bean-to-cup machine. Set the water hardness straight away, otherwise the machine asks too late.

Use the descaler the maker specifies, not vinegar or citric acid from the cupboard. Vinegar attacks rubber and aluminium, and damage from the wrong descaler is exactly the kind that falls outside the warranty.

See also: Water hardness, Water filter

Every machine ships with a test strip. Dip it, read the value, set it in the menu. After that the machine knows how often to ask for descaling.

It takes a minute and it is the most commonly skipped step of setting up.

Hardness varies a lot by region in the Netherlands: from very soft in parts of Limburg to hard in the west. Your water company publishes the figure for your postcode, which is more accurate than the strip and takes a minute.

See also: Descaling, Water filter

Philips calls it AquaClean, Jura uses CLARIS. The cartridge reduces the scale entering the machine, so it needs descaling less often.

They are consumables, and over a few years they add up. Count them in when comparing two machines on price.

A filter does not replace descaling, it postpones it. Machines set up for a filter ask for descaling less often, but anyone who does not change the cartridge in time gets the worst of both: no protection and a machine that is not asking.

See also: Descaling, Water hardness

Makers quote the capacity in servings rather than litres, because that is the number you can act on: it is how many coffees before the machine interrupts you. Philips counts on 12 pucks, Jura on about 16.

A bigger container mostly matters when several people drink from the same machine.

Empty the container before the machine asks, especially if you are leaving it a few days. Damp grounds in a closed machine go mouldy, and you taste that in the first cup afterwards.

See also: Brew group

When a shop shows “was €699”, that is a claim by the party selling the thing, not by the manufacturer. We record it under the shop’s name and repeat it as something they say.

We keep that claim per day. A discount is more often manufactured by raising the reference than by lowering the price, and only a dated record can show it.

Around Black Friday this matters most. A shop that raises its reference in October and shows "40% off" in November is selling at roughly its September price, and that is exactly what a daily series makes visible.

See also: Price verdict

We measure every machine’s price daily and compare today against what we saw before. That produces “lowest ever”, “sharp”, “average” or “dear”.

While there are too few measurements, we say so. We never base the verdict on a shop’s struck-through price. That is exactly how comparison sites end up promoting permanent discounts.

So a new model has no verdict at first. That is not an omission but the point: we would rather say nothing for a month than say something immediately on the strength of three readings.

See also: Reference price