Espresso, Explained · Part 11 Coffee oil does not dissolve in water. Flushing water through will not remove what has built up, and cleaning means a detergent made for the job and a basket with no holes. 01 Flushing water through is rinsing, not cleaning Every shot leaves oil behind. It coats the water path and the screen the water comes through, and over time it builds into a layer. Water passing over that layer carries the taste of it into the cup. Oil does not dissolve in water. It is the same reason you use detergent on a greasy pan. A few flushes take off the loose grounds you can see and leave the oil exactly where it was. You taste it before you see it. If the first shot of the day smells stale or the finish is muddy, look at the machine before you blame the coffee. 02 You need a blind basket and a proper detergent A basket with no holes gives the water nowhere to go. It is pushed back into the machine instead, washing the path on the way. A normal p...

Choosing a Grinder · Part 4 What you drink decides which grinder you need. Espresso demands fine adjustment steps; if you only brew filter, something simpler will do. 01 Start from how you brew Espresso is the demanding case. It needs a very fine grind, and a small move on the dial changes the cup a great deal. Without closely spaced adjustment steps you cannot land where you want. Filter brewing gives you room. At a coarse setting, one step matters far less in the cup. For the same money you can choose a simpler machine than an espresso grinder. Doing both means buying for espresso. A grinder that handles espresso will handle filter, but a filter-oriented grinder often cannot adjust finely enough in the espresso range. 02 Hand grinders and electric ones A hand grinder gives you better burrs for the money. What would have gone into a motor goes into the burrs and the shaft instead. For one or two cups a day this is the better buy, and there is almost no he...

Espresso, Explained · Part 10 There is no evidence that a shot becomes undrinkable after 30 seconds. Three things do change in the cup, and all three move at very different speeds. 01 Where does 30 seconds come from The instruction to drink it immediately has been repeated for a long time. The number has no clear source and no experiment behind it. It looks more like a phrase that settled in after people read the disappearance of crema as the disappearance of flavour. Three things actually change in the cup. Temperature falls, crema collapses, and oxidation proceeds. They run at different speeds and cannot be collapsed into a single number. A shot without crema is not a spoiled shot. Foam going flat and flavour falling apart are separate events. Throw the cup away on the strength of the crema and you are discarding perfectly good coffee. 02 What changes, and how fast Temperature moves first. An espresso is a small volume, so it cools noticeably within tens...

Espresso, Explained · Part 9 Decaf is not ordinary coffee with the caffeine removed. Taking the caffeine out puts the green bean through water and heat, which leaves it more porous, so the same settings give you a different shot. 01 The bean has already been through something Removing caffeine means wetting the green bean and applying heat. Whichever process is used, that much is common to all of them. What comes out the other side is a bean with a looser structure that breaks apart more easily. It behaves differently in the roaster too. Colour darkens early and the cracks sound faint. It is hard to judge by surface colour alone, which makes it demanding to roast well. Caffeine is not gone entirely. Most of it is removed, but a small amount remains. It is safer not to describe it to a customer as caffeine-free. 02 It grinds finer at the same setting A bean that breaks easily produces smaller particles at the same dial position. It also produces more fines....

Espresso, Explained · Part 8 Oat milk curdling in coffee is not a sign that it has gone off. It lacks the protein that lets dairy survive acid and heat, and choosing the right product and stopping at a lower temperature prevents most of it. 01 Dairy has something plant drinks do not Milk protein is relatively stable against acid and heat. Espresso is acidic and hot. Milk holds together in those conditions because of casein. Plant drinks do not have it. Proteins from oats or soya clump together when they meet acid. That is what you see as specks floating on the surface or a drink that looks split. It has not spoiled. The same thing happens with a carton opened yesterday. Check the conditions before you throw it away as a storage problem. 02 Barista versions are built for this A barista oat drink has been adjusted for coffee. Added plant oils and stabilisers reduce the clumping, and the acidity is balanced so it holds up against espresso. It also foams bette...

Choosing a Grinder · Part 5 Grinding well is not enough for a café. The machine has to survive a day's volume and keep the cup steady while it runs back to back. 01 Start by converting drinks into kilograms Turning cups into weight gives you a figure to shop with. At around 20 g a drink, 200 drinks a day is 4 kg. Whether a grinder handles that number is the first question. The real test is the busy hour. Look at how many drinks leave in the morning hour rather than the daily total. If the grinder cannot keep up then, the whole day runs behind. Buy with headroom. Buy to your limit and you replace it as soon as sales grow. One tier above your expected volume is usually the cheaper decision. 02 What happens when it runs continuously Hot burrs produce different particles. Metal expands very slightly with heat, the burr gap shifts, and the grind size moves with it. That is why a setting dialled in at opening is off by lunchtime. Heat costs aroma too. W...

Choosing a Grinder · Part 3 Every grinder holds on to a little coffee. Since that coffee comes out in your next shot, consistency matters more than the amount. 01 Not everything you grind comes out Ground coffee has to travel a path to reach the exit. That path has corners and gaps, and some of the coffee sticks in them. It is why you grind 20 g and catch 18 g. What stays behind comes out next time. Grind today and yesterday's grounds arrive first. A day-old dose has lost aroma, and it dulls the cup by exactly that much. Oily coffee sticks more. Darker roasts and older beans leave more oil along the path. Given time, that oil hardens and starts to smell. 02 The problem is the variation, not the quantity A constant amount left behind is not much of a problem. If you never catch quite what you put in, but the amount you catch is always the same, your settings still hold. You simply work from that figure. In practice it moves. Change the dial, change the cof...

Choosing a Grinder · Part 2 Saying that flat burrs cut and conical burrs crush overstates it. Both act on the bean with shearing and compressive force at once, and the difference that actually shows up is the distribution of particle sizes. 01 The two shapes work differently Flat burrs are two discs facing each other. Beans enter at the centre and are pushed outward as they are ground. Because centrifugal force does the ejecting, the burrs have to spin quickly, and that generates more heat. Conical burrs are a cone turning inside a ring. Beans travel downward through a gap that narrows as they go. Gravity does the work, so a slower rotation is enough and less heat builds up. How the grounds exit explains the rest. Rotation speed, heat, and how much coffee is retained all follow from that structure. None of it settles which type is the better machine. 02 Where the cut-versus-crush story breaks down The idea that flat burrs cut and conical burrs crush has bee...

Choosing a Grinder · Part 1 A better machine stabilises your conditions. A better grinder changes the cup. With the same money to spend, the grinder comes first. 01 Coffee is made by the particles, not the water What an espresso machine does is deliver hot water at a steady pressure. What that water passes through is not up to the machine. It passes through the grounds the grinder produced, and the size and evenness of those grounds decide most of what ends up in the cup. The machine holds the conditions. Stable temperature and steady pressure mean repeatable results. A good machine reduces failures; it does not create flavour that was never there. The grinder sets the ceiling. Even particles let water pass evenly and sweetness comes through. Uneven particles mean parts of the same shot are over-extracted while others are barely touched, and no machine fixes that. 02 What uneven particles do Coarse and fine particles dissolve at different rates. With both ...

Espresso, Explained · Part 12 Burrs are not a part that fails. They wear a little every day, and replacement is measured by the total weight of coffee they have ground rather than by how long you have owned them. 01 Dull burrs crush instead of cutting Sharp burrs cut the bean. Cut particles come out at a consistent size with fewer fines, water passes evenly, and the cup stays stable. Worn burrs press and break instead. Particle size scatters and fines increase. The same dial setting now gives you a different cup each time, sweetness drops, and astringency arrives earlier. Still spinning is not the same as still working. Burrs do not snap and stop. They wear down gradually, and nothing having broken is not the same as the part doing its job. 02 Count kilograms, not months How many years you have had them tells you nothing. A café grinding 2 kg a day and one grinding 20 kg a day do not share the same year. The measure is the total weight that has pass...

Espresso, Explained · Part 7 An iced americano gets diluted twice as the ice melts. Deciding the finished volume before you build the drink, rather than filling with ice and topping up, is what makes it repeatable. 01 Dilution happens twice The first round happens while you build the drink. Hot espresso hits the ice and melts the surface of it immediately. Water has already been added before the glass leaves your hand. The second round happens while it is being drunk. Heat from the hand and the room keeps the ice melting. That is why a drink that tasted right when you made it turns watery ten minutes later. So the reference point is the drinking, not the making. A glass consumed at the counter and one carried out of the door cannot be built the same way. 02 Do not fill with ice and pour into what is left Filling the glass with ice first leaves a different amount of room every time. Cube size and how they stack decide the space that remains. That is why the...

Espresso, Explained · Part 6 Reach for the grinder first and you will never find the cause. Check whether water passed evenly, then how much you extracted, then how strong the cup is, in that order. 01 You need a fixed order of operations When a shot tastes wrong, most people move the grind first. Shot time changes, so it feels like progress. If the cause was somewhere else, the problem stays put and your settings are now scrambled as well. There are three checks, in sequence. Did water pass through evenly, how much did you pull out of the coffee, and how strong is the cup. If the first one has failed, you cannot judge the other two. Change one thing at a time. Move the grind and the yield together and you learn nothing about either. Write down what you changed and how it tasted, and the next coffee takes half the time to dial in. 02 Step one: did water pass evenly If this is broken, every later judgement is wrong. A shot where water escaped down one path ...