The World Atlas of Coffee: From beans to brewing - coffees explored, explained and enjoyed

by James Hoffmann

  6 Remove the handle from the scales and tamp the coffee flat in the basket, keeping your wrist straight, to make sure the coffee bed is even. Leaving the tamper on top of the coffee – observing the angle of the handle will show you whether or not it is sufficiently flat. C

  7 Weigh the cup or cups into which you are going to brew the coffee.

  8 Turn on the machine to flush some water through the group head. This will help to stabilize the temperature of the brew water, as well as rinse off any coffee grounds remaining from the previous brew.

  9 Carefully lock the handle into the machine and arrange the cup(s) in place to receive the coffee.

  10 Get your timing device ready. If the machine doesn’t have a time display showing you how long the shot has been brewing, use a simple stopwatch on your mobile phone or a kitchen timer.

  11 As soon as possible, start brewing the coffee. When you start to brew, start the watch. Brew the coffee for the length of time recommended by the roaster. If you don’t have a recommendation, try somewhere between 27 and 29 seconds.

  12 When the desired brew time is up, stop the machine. When the handle has finished dripping (after a few seconds), return the cups to the weighing scale to check how much coffee you have made.

  The original home of the espresso is Caffe Florian on St Mark’s Square, Venice, which has been serving coffee since 1720.

  JUDGING THE RESULTS

  Ideally, the weight should be within a few grams of the roaster’s recommendations. If it is not, we can make a simple change to try next time:

  • If there is too much liquid, the flow was too fast. We need to slow the water down by grinding the coffee finer.

  • If there is not enough liquid, the flow was too slow. We should increase the flow rate by grinding the coffee more coarsely.

  For many people this kind of precision seems a little extreme, and some prefer to use volume in the cup (gauged by eye) instead of weight. This same protocol will work, but it is not as accurate.

  Once a grinder is set for a particular batch of coffee, there will be limited need to adjust it, unless your home is subject to dramatic swings in temperature during the day.

  CHANGING THE GRIND

  With espresso, you really need to be grinding the coffee yourself with a burr grinder that allows you to adjust the grind size easily. When you start brewing a new bag of coffee you will need to set the grinder for it. The term we use for setting a grinder in the industry is ‘dialling in’.

  Just about every grinder has some ground coffee left inside it after grinding. This means that if you change the grind setting, the first coffee it will push out will actually be the old grind size. A common practice is to purge the grinder by grinding a few extra grams of beans at the new size to push out the old grounds, and then to throw this coffee away. If you change the grind size but don’t see a change in the brewing process, it is likely you did not purge enough coffee from the grinder.

  I would always recommend making small changes when adjusting a grinder. When you get a new grinder, it is a good idea to buy some cheap (though ideally fresh) coffee to play with to make sure you understand how big an effect a small change in the grind setting has on the brewing process. Most grinders have numbers on the settings. The actual value of the numbers is meaningless, but if you want to grind finer, turn the dial to a smaller number and vice versa. Many grinders have marked steps that you can select, sometimes whole numbers and sometimes divisions of numbers. Start by changing the setting by a single step when the grind is wrong.

  BREW RATIO

  There are many different styles of espresso, and people have different preferences for how long or strong they like their espresso to be. Commercially we tend to talk about the brew ratio: how much liquid should you be brewing from a fixed weight of ground coffee? My own personal preference, and recommended starting point, is to brew two parts of liquid out of one part ground coffee. For example, if I start with 18g of ground coffee, I would want my espresso to weigh 36g (2 x 18). The Italians generally prefer a smaller coffee, so if I were making a double espresso I might use 14g of ground coffee to produce 28g (2 x 14) of liquid. The ratio of coffee to water is fixed to maintain my strength preference.

  If I want a stronger espresso, I can change my ratio. Instead of 1:2 I might use 1:1.5, which would mean my 18g of ground coffee produces only 27g (1.5 x 18) of liquid. This shorter espresso will be very strong, and I would have to adjust the grind finer so the brewing process takes a similar amount of time. If I just let a smaller amount of water come through at the same flow rate as before, the brew will be over faster and I will have failed to extract all of the good flavours that I want.

  BREW TEMPERATURE

  The coffee industry is only now recovering from an obsession with the stability of brew temperature in espresso brewing. Changing the brew temperature does have an effect on the extraction and the taste of the coffee, but I don’t believe it is as important as many make it out to be. The hotter the brew water, the more effective it will be at extracting flavour. So for lighter roasts I would recommend a higher brew temperature than for darker roasts, which give up their flavours more easily.

  There are claims that a change in temperature of 0.1°C (0.18°F) will change the taste of the coffee. I believe that to be nonsense. I think 1°C (1.8°F) creates the smallest change that most of us could detect, and that a slightly incorrect brew temperature is so rarely the reason I am served a poor espresso.

  If you can control the temperature on your espresso machine, I would recommend a water temperature of between 90°C (194°F) and 94°C (201°F). If the espresso does not taste right, try adjusting other aspects of the recipe first. However, if there is a persistent negative taste (such as a constant sourness) try increasing the temperature, and if there is a persistent bitterness, try decreasing the temperature (after you have checked your equipment is properly clean).

  A meeting place for artists, intellectuals and students, College Street Coffee-House, near the University of Calcutta in Kolkata, India, has played an important role in the city’s cultural history.

  BREW PRESSURE

  The first espresso machines created pressure using a compressed spring to push the water through the coffee. As the spring expanded, the pressure it produced would decline, so it started with a very high pressure and ended up relatively low. When electric pumps became common, they needed to be set at a constant pressure. Some say that the setting of nine bars (130 psi) was chosen because it was the approximate average of the varying pressure created by the springs on older machines.

  Luckily, this also appears to be the pressure at which we get the best flow rate. At pressures below nine bars, the coffee bed provides so much resistance that the flow rate drops. At pressures above nine bars, the coffee bed becomes so compacted that the flow rate drops again. As long as your machine produces roughly the right pressure you should have no trouble. If the pressure is too low, your espresso may lack body and the desired creaminess. At very high pressures, there can be a strange woody bitterness to the espresso that is not enjoyable.

  There is now equipment available that allows baristas to adjust the pressure of their brew water, but there is not yet enough data to make a viable case for introducing this technology to home machines.

  CLEANING AND MAINTENANCE

  I would estimate that 95 per cent of the commercial coffee machines in business throughout the world are not cleaned properly and this is one of the reasons people are served disappointing, bitter and unpleasant coffee every day. There is no such thing as too clean, and although it requires a little bit of work each time you finish making coffee, a clean machine will make your coffee taste consistently sweet and clean.

  COFFEES ROASTED FOR ESPRESSO

  Espresso is quite different from the other brewing methods, and because of the small amounts of water being used it is often a challenge to fully extract the coffee. Additionally, because the concentration is so high (the coffee being so strong), balanc
e is very important. A coffee that may taste delicious and balanced as a weaker brew can become dominated by overpowering acidity when consumed as a stronger cup.

  For that reason, many roasters change how they roast their coffee when they know it is going to be used for espresso. Though this practice is not universal, I would certainly recommend a slightly slower and slightly darker roast for espresso than I would recommend for a coffee being brewed with a filter.

  However, roasters around the world disagree strongly about what the right level of roast is for espresso and there is a wide spectrum on offer from relatively light through to a much darker roast. Personally, I prefer lighter roasts because they allow the particular characteristics of the raw coffee to be appreciated. Darker roasts often carry a more generic ‘roasted coffee’ flavour, and also have a higher level of bitterness, which I don’t enjoy. What I prefer is only really important to me, however, and everyone has their own preference.

  The darker the roast of coffee, the easier it is to extract. This is because the coffee bean becomes increasingly porous and brittle as it is roasted. This means that less water is required in the brewing process to properly extract the coffee. If body and mouthfeel are important to you, then you might prefer slightly darker roasts brewed at a 1:1.5 brew ratio. If sweetness and clarity of flavour are important, I would recommend a lighter espresso roast brewed at a ratio of 1:2.

  • When you finish making coffee, remove the basket from the handle and clean underneath it with soapy water on a scourer. If you don’t do this, an unpleasant patina of dried coffee will accumulate there and it will smell and taste awful.

  • Espresso machines dispense water through a mesh screen. If this is easily removable on your machine, take it out and clean it, and also clean the water dispersion block it sits against.

  • While the dispersion screen is out, clean the rubber gasket. If coffee builds here, the basket won’t make a seal against the machine and water will leak out during brewing, often dripping down the sides of the brew handle into the cup.

  • Remove the brew basket from the handle and replace with the cleaning basket. This is the basket with no holes in it that will have been supplied with your machine.

  • I recommend using a commercial espresso machine cleaner at the end of every session of coffee making. This will clean out any liquid coffee left inside the machine, which will turn increasingly rancid and unpleasant over time. Follow the manufacturer’s instructions for how to use a cleaning powder on your machine.

  • Make sure the steam wand is clean if you have used it.

  Some people claim that a machine can taste too clean, and that you need to brew an espresso or two to ‘season’ it after cleaning to take away the metallic taste. I have never found this to be the case, and as long as your machine is properly warmed up (add at least ten to fifteen minutes on top of manufacturer’s recommendation), it should make great coffee straight away.

  I recommend keeping the machine switched off when not in use. Use a timer to make sure it is ready to make coffee when you want it, but turn it off when you have finished. Espresso machines use quite a lot of power and it is a waste to leave them on if they are not being used.

  To keep your machine in good working order, make sure the water you use is suitable. If you use hard water, limescale will build up quickly in the machine and cause it to malfunction. Many manufacturers offer advice for descaling, as some limescale will form even in soft water areas (it will just take a lot longer). Err on the side of caution because if you let your machine scale up completely, it may be difficult to descale without help from a professional (and a bill to go with it).

  Over time, the rubber gasket in the group head may need changing. When you lock in your brew handle, it should stick out at ninety degrees to the machine. If it starts to twist much further across, the rubber may be wearing and it should be replaced.

  Customers congregate around baristas at London’s first espresso bar, the Moka Bar at 29 Frith Street, which was established in 1953 and opened by the Italian actress Gina Lollobrigida.

  STEAMING MILK

  Well-steamed milk combined with well-brewed espresso is a wonderful sensory experience. Great milk foam is like liquid marshmallow: soft, moussey and undeniably enjoyable to drink. The goal is to create bubbles so small that they are almost invisible (often called ‘microfoam’). Foam like this is elastic and pourable, and adds a wonderful lift to the texture of drinks like cappuccino and café latte.

  It is important to use fresh milk for steaming. As it reaches its use-by date, milk tastes fine and is still safe to drink but it starts to lose its ability to create a stable foam. It will foam as normal when you steam it, but the bubbles will soon break down. If you lift the jug of foamed milk to your ear, you will hear it fizzing like a freshly poured soda as the air escapes.

  When we steam milk we have two separate tasks to accomplish: we must whip in air to create the bubbles and we must heat the milk. With most steam wands it is best to tackle one task at a time, so the first thing to focus on is creating the bubbles. Then, when we have added enough air to the milk and it is the desired volume, we can focus solely on heating it to the desired temperature.

  THE RIGHT TEMPERATURE

  The ideal temperature for milk, when combined with coffee, is a subject of some contention between many coffee shops and their customers. Milk begins to irreversibly degrade in flavour and texture above 68°C (154°F). This is because the heat alters and denatures the proteins, creating new flavours, though not always good ones. The smell of cooked milk reminds me of eggs at best, and baby sick at worst.

  A very hot cappuccino will lack the texture, flavour and sweetness of a drink made with milk that has only been heated to 60°C (140°F). It is impossible to produce good microfoam when the milk has been heated to boiling point. Unfortunately this is the nature of milk – we can either have a very hot or a very delicious drink. This is not to say that all drinks should be served lukewarm, instead that they should be enjoyed as soon as they are made.

  WHOLE MILK OR SKIMMED?

  It is the protein in the milk that supports the bubbles, so milk will foam well regardless of whether it is skimmed or whole. However, the fat content does play a role: it adds a wonderful texture to the drink, but also changes the way flavour is released. A cappuccino made with skimmed milk has an immediate, intense coffee flavour which does not linger. If the cappuccino is made with whole milk, the flavours will be less intense but will last longer. I always recommend using whole milk, but I also prefer relatively small milk drinks. I think a small, rich cappuccino is a delight.

  STEAMING MILK METHOD

  This technique is suitable for traditional steam wands. If your machine has a range of attachments or automatic frothing functions, follow the manufacturer’s instructions.

  1 Start by pointing the steam wand over the drip tray or into a cloth and briefly opening the valve. This will get rid of any condensation inside the wand. This is known as purging. A

  2 Pour cold fresh milk into a clean stainless-steel steaming pitcher. It should not be more than sixty per cent full.

  3 Dip the steam wand into the milk so just the tip is submerged.

  4 Open the valve to full flow and gently lower the pitcher until the wand is almost out of the milk. Listen carefully: you want to hear the slurping sound of the steam wand start to whip air into the milk. As the milk expands, lower the pitcher a little more to bring it back to the surface if you wish to add more air.

  5 When you have your desired amount of foam, which should ideally happen before the milk feels warm to the touch, then submerge the steam tip again to start heating the foam – you want it to be just under the surface. Position it slightly to one side and you will see the milk start to spin and churn. The process should now be relatively quiet.

  6 To test whether the milk is warm enough, place your free hand on the bottom of the jug. Continue to heat the milk until the jug becomes uncomfortable to touch. At this point the
milk will be about 55°C (131°F). Remove your hand from the bottom of the jug and continue to steam for three to five seconds, depending on how hot you like your milk. B

  7 Close the steam valve fully and put the milk pitcher down. Wipe the steam wand with a clean, damp cloth and purge the wand into the cloth to remove any leftover milk from inside the wand.

  8 Don’t worry if your foam contains a few large, ugly bubbles. If you let it sit for a few seconds, the milk will drain off the surface of the larger bubbles, making them very brittle. A couple of gentle taps of the steaming pitcher on the counter will usually pop them.

  9 If you want to pour a combination of milk and foam into your drink, which I strongly recommend, you must make sure that they are fully combined. After the tapping, swirl the milk and foam together, much like you might swirl wine in a glass before smelling it. You can be quite aggressive, as you want to make sure that the liquid milk is fully combined with the wonderful microfoam. Swirl until the milk foam has a glossy finish, then pour it into your drink. C

  ESPRESSO EQUIPMENT

  There are espresso machines to suit almost any budget, from cheap units with which you can make a start, to smarter machines that can cost as much as a small car. All of them are designed to do the same thing: heat water, then push it forwards at high pressure.

  The more money you pay, the more the machines improve in build quality, control and consistency. Most of this consistency concerns how the machine heats water, and how it creates water pressure, and different types of espresso machine achieve this in different ways.