The Barista as Alchemist :
The 'shot' :
Temperature :
A continual cleaning routine must be automatic :
Roasting and Caramelisation :
The grind :
The key to espresso is 'extraction' :
Crema :
Water :
Beans :
The art, craft, and science of milk preparation for 'Latte' and 'Cappaccino' :
Choice magazine reccommendations regarding home espresso machines and grinders :
Serving suggestions: Doppio, ristretto, American, Cappuccino, Latte, Macchiatto, Corretto :
Sugar? :
Making coffee at home :
It has been said that good coffee is attributable to the coffee (25%), the equipment (25%), and the Barista , or ‘barman’ (50%). The Barista must master the art and science of coffee making. Even regular customers will walk past their favourite café if ‘their’ Barista is not on duty. Even a cappuccino costs no more than 40c to serve a customer. Coffee is by far the most profitable item on any café menu, returning a margin of over 80%.
Temperature
A continual cleaning routine must be automatic More generally, residual coffee grinds can build up in the group head, in the ‘showers’ (the mesh inside the group head that even distributes the heated water ), and in the group handle basket. The new coffee will run through the old already extracted residual grounds. These grounds will become ‘over extracted’, and add a bitter or burnt taste to any further coffee that is made.
Run water through the group head before each shot, to wash out any residual grinds that can get forced back up the head. Ideally wipe the group handle basket with a dry cloth after every shot (washing them can lead to water building up between the group head and the basket, which can take on a metallic taste, and taint the espresso). Otherwise loosely connect them to the group head and run hot water through for a few seconds while agitating, or moving right and left. This cleans the head and the handle and basket. Take care that water doesn’t build up between the basket and group head as previously mentioned.
The steam nozzle should be ‘bled’ (i.e run steam through) for a few seconds before every use, in order to remove overheated water and any milk that may have been forced back up the nozzle, and should be wiped clean with a cloth after every use.
Don’t hand tea towels etc on the machine, as this will keep them warm, and ideal for bacteria etc!
Roasting
The heat applied during the roasting process initiate chemical reactions which produce aromatic oils, produce some acids and break others down, and unlock the flavour and aroma of the raw coffee bean.
As the grinding plates in your grinder age, they wear out, and lose their edges. Blunt grinding plates produce heat which can ‘burn’ the coffee.
The key to espresso is Extraction
The term ‘extraction’ refers to the amount of time that water is in contact with the coffee grinds. The longer the water is in contact, the greater the amount of caffeine, and bitterness, as more of the actual grind is dissolved in the water. Caffeine is water soluble.
The ideal extraction time for espresso is 25 – 30 seconds. This is the amount of time it should take for the water from the group head to be forced through the grinds in the group handle. The extraction is a function of the quantity of grinds in the group handle, how finely or coarsely they have been ground, and of how firmly they have been compressed i.e pushed down with the ‘tamper’.
Make sure the group handle is attached firmly to the group head i.e push right hard, so that the seal between the group handle and group head is complete. If you can’t get a good seal, you should inspect the rubber seals to see if they are cracked or brittle, and replace them where necessary.
We must remember that espresso machines produce constant water and pressure for a double group shot. The machine must be calibrated for a double shot, in order for it to be able to make double shots i.e two cups at once, or a ‘doppio’ i.e double shot of espresso. This means that the water pressure has been ‘tuned’ or ‘calibrated’ for a double. Espresso machines produce this constant water pressure.
This explains why you don’t simply use half as much coffee to make a single as a double, as some naive people believe. It is a matter of mechanics and physics. Given that the water flow and pressure is constant, we can only adjust the quantity and tamp to get the ideal extraction for a single. Less coffee means less resistance, meaning that simply placing less coffee in the group handle basket will immediately increase the flow, making it much faster, and hence shortening the extraction time. We therefore cannot simply halve the quantity of coffee to make a single shot. We have to compensate for the decrease in resistance produced by the reduced quantity of coffee.
I have come across various recommendations for the quantity of coffee you should use for single and double shots of espresso. Some recommend 10g for a single, and 14-15g for a double, when using commercial espresso machines. Another manufacturer recommends 13g of only lightly tamped coffee for a single shot, and 19.5g of firmly tamped grounds for a double (i.e two single shots or one ‘doppio’. Today many consumers will ask for a double shot, either as a straight espresso, or as a form of latte.
Perhaps the water pressure of each commercial espresso machine has a particular proprietary water pressure. The manufacturer will know the exact operating pressures, and can therefore suggest the optimal quantity of coffee to optimalise the extraction process.
Barista’s recommend using a metal hand tamper, and not the one attached to the espresso machine. Grinds are to be heaped onto the basket. The Barista is to quickly wipe their finger across the top of the rim, (ideally some sort of metal guide would be used i.e more hygienic, say a metal ruler or some patented product…maybe someone will get rich from this suggestion!), to make the heap level with the rim. The smaller end of the tamper should be used to ‘tap’ the group head on the ‘cleat’, to bring the grinds into the center of the ‘basket’. The larger end of the taper should be forced down onto the grinds, compressing them, with an ideal force of around 10kg for a double shot, and only lightly for a single. We will see why a little later. The rim of the basket should be brushed free of grinds, so that the group handle can seal with the group head, and so that any remnants on the group handle don’t get ‘over extracted’ or ‘burnt’, thus adding unwanted bitterness to the espresso.
There are a number of signs to look for (and listen to in the case of milk preparation), which you can use to adjust your grind.
ideally your extraction should take 25 to 30 seconds. Apparently the ideal water flow through coffee is 40 ml of water in 30 seconds. Given that the water pressure is constant i.e calibrated for a double shot, we can only vary the amount of coffee, how tightly it is ‘tamped’, and the length of time water is allowed to pass through it. Together, these three variables determine, with the constant water pressure, the ‘extraction’ of the coffee.
The extraction should ‘pour’ like a ‘rats tail’. It should pour smoothly once it starts, in a thick flow, arching outwards (hence the term ‘rats tail’). If the flow is too slow, the coffee will be over extracted and taste burnt or bitter. If the flow is too fast, the coffee will be under extracted, producing a sour or acid taste.
Crema
The crema will also provide an indication of whether your extraction times, and therefore grind, is correct. A too dark crema may indicate over extraction, as may a white spot in the middle of the cup, or a white crema with big bubbles. Adjust the grinder right to grind finer. If the crema is too light, or dissolves quickly, then your coffee may be under extracted. Adjust the grinder left, to grind coarser. The grind must be calibrated new whenever the flow and crema are not ideal. Simply make a double shot, and then control the quality i.e observe the flow and crema. Make any adjustments necessary, and make a double shot. Repeat the process until the flow and crema are ideal. As we have noted, changes in the temperature and humidity, and sometimes even beans, may mean that you will need to calibrate the grind as you go. Simply observe the flow and crema, i.e constant quality control, of your shots, and when necessary, make adjustments to the grind. Most grinders have a large horizontal wheel that you turn to the right ( finer) and left (coarser).
The ideal crema is a thick, hazelnut colored cream.
Note that the crema is dependant on the extraction overall. The extraction is also dependant on the temperature of the water. The variables that we can control are the grind, the time the water is in contact with the grounds by manually dispensing the hot water with the manual control ( the button you use for ‘flushing’ the heads), and the tamping pressure and quantity of coffee we put in the group handle basket. We can also ensure that the machine is operating at its optimal temperature and pressure levels. We cannot change these, but we can call on the manufacturers’ service and technical support to do so.
Another indicator that you should monitor in your quality control is the appearance of the grinds after they have been extracted. Ideally, when you bang the group handle on the grinds bin, the grinds should come out as one piece, a sort of relatively dry ‘biscuit’.
Water
If the machine is left idle for more than 10 minutes, water in the heat exchanger can become hotter than desirable. You should run the group heads to bleed the excess steam and heat that build up. Otherwise this steam and over-hot water can ‘burn’ the coffee. It is best to run the group heads for a few seconds before every cup in any case, to clear the heads of any residual grounds.
Beans
Beans keep 7-10 days. Don’t freeze them as this can change the chemical composition of the beans. Store in airtight container, in cool dry environ. If you do keep any ground coffee overnight, seal it in an airtight container and place this is a cool dark environ.
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Milk preparation for ‘latte’ and ‘cappuccino’
The art and science of milk preparation for ‘latte’ and ‘cappuccino’
Use a separate jug for preparing each type of milk. Make sure the milk is fresh and stored at 5 degrees Celsius. Use the smallest jug you can that allows the following. Fill the jug one third, to about a centimetre below the spout. Using the spout as a guide, angle the jug slightly, and lift the jug until the steam wand is just below the surface of the milk. Hold the jug with your left hand in this position.
With your right hand, turn the steam up to full. Lower the jug slowly as the milk rises. The acoustic signature of correctly steaming milk for the first 10 seconds is a Ch Ch sound. For ten seconds slowly lower the jug, achieving that Ch Ch sound, and keeping the wand just below the milks surface. Keep tapping the side of the jug with your right hand. In about 10 seconds it will feel about body temperature. Remember it starts off at 5 degrees. This body temperature is around the ideal 37.8 degrees that we want to attain after 10 seconds. This is the ‘stretching’ phase of the milk preparation. What we are doing is stretching the milk fat globules so that they take on more volume. We have to avoid breaking the milk fat globules with too much heat.
Within these 10 seconds the milk will have doubled in volume. Tapping the right hand on the jug until it feels approximately body temperature, we then raise the jug and therefore dive the wand into the milk. We are now ‘rolling’ the milk. Ideally you will find a ‘sweet spot’ in the jug which ‘rolls’ the milk over. We continue tapping the jug with our free right hand until it feels too hot to touch i.e 60 to 65 degrees Celsius. The milk temperature should not exceed 70 degrees Celsius. At this temperature the milk calcium can burn, making the coffee taste bitter and burnt. The milk fat globules can also explode, separating into protein and water. The meringue consistency we are seeking is then impossible to achieve. This ‘rolling’ process ideally takes 20 seconds.
Remember to keep removing your hand when you are ‘tapping’ the jug, checking for temperature, otherwise your hand will lose sensitivity to the heat. Perhaps there is a market for a milk preparation jug which has a thermometer and timer built in?
You could use a thermometer, and a stopwatch while practising, and learning to remember the acoustic and visual quality control indicators.
Once the milk jug is too hot to touch, keep the nozzle deep in the milk while turning the steam off. It is critical that you do not remove the wand until the steam has stopped. If you do, you will ruin the milk by blowing it full of large bubbles. Remember the correct consistency we are seeking is a thick, rich, silky-glossy meringue.
You must add this prepared milk to your cappuccino immediately, before the milk separates into hot milk and foam. Tap the jug on the bench to break any large bubbles, and pour your cappuccino onto a shot of espresso, and fill the cup. The meringue foam will break down in the cup into hot milk and meringue.
Some people will claim that it is o.k to pour hot milk over the espresso, and then spoon froth on top of it. This is how a cappuccino is prepared in the ‘Australian’ style.
To make a latte, wait a few seconds while the milk separates, and then pour the hot milk into the glass over the espresso shot, and then pour or add the last 10 mm of foam.
Remember to use the smallest jug you can. Never reuse the heated milk to make meringue. Always only make as much as you need, using fresh cold milk. A cappuccino requires one third hot milk and one third meringue foam. This means you will need a jug for 30 ml. Remember that the milk will be stretched to double its volume, and as such you use half as much fresh milk per volume than you need to serve i.e 30 ml milk to make the 60ml volume to add to the 30 ml espresso shot.
Always clean the nozzle directly after pouring the cappuccino with a damp cloth. Serve the coffees immediately.
Use methods taken from psycho cybernetics initially. Visualise going through the process in your mind, noting the method, what actions you have to take and when, and what you are looking for as quality control and timing indicators.
Then do a dry run at the machine, pretending you are turning on the steam etc.
Once you have the actions clear in your head, practise with enough milk for a single cappuccino. Practise until you are confident. You can drink the milk, or make lattes and cappuccinos for your friends. Treat it as fun, and don’t be discouraged if it takes a lot of practise to get it right.
Your ideal meringue foam will be shiny, glossy, thick, and dense, with really compact foam.
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Serving suggestions: Doppio, ristretto, American, Cappuccino, Latte, Macchiatto, Corretto
Serving suggestions
A Ristretto is half the volume of a standard shot. The same quantity of coffee is used. The quantity of water pressed through it is merely halved. A ristretto is 15ml.
A Doppio is a double shot of espresso.
An American, or ‘long’ espresso is a double shot of espresso poured over a glass partly filled with hot water, to smooth out any bitterness or harshness. It is important to avoid using too large a cup, and thereby diluting the espresso too much with water or milk. Traditional porcelain and glass cups are recommended for this reason.
A cappuccino is a single shot of espresso (30ml) with a topping of hot milk and meringue foam. The foam is traditionally added immediately in one go. The foam then breaks down into milk and meringue. The cappuccino is, by volume, one third espresso, one third hot milk, and one third meringue foam. Remember that the volume of milk used is actually equal to the volume of espresso, just that it ‘stretched’ and ‘folded’ into a greater volume containing air and ‘stretched’ milk fat molecules. Sometimes a sprinkling of drinking chocolate is added.
A Latte is a shot of espresso poured over heated milk. 10mm of meringue foam is added to the top.
A Vienna (an Australian invention) is made by topping an espresso or doppia (i.e single or double shot of espresso) with whipped cream and grated dark chocolate.
A Macchiatto or ‘stained’ espresso is an espresso ‘stained’ with a dash of hot or cold milk which produces a striped or marbled effect, topped with a dollop of meringue-foam.
A Latte Macchiatto , or ‘layered’ latte, is a third milk, topped with meringue foam. A Doppio, or double shot of espresso is poured over the tip of a dessert spoon.
A corretto is an espresso ‘corrected’ with liqueur. Cognac, Anise, Almond, and Hazelnut liqueurs are common.
Sugar?
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Home espresso machines and grinders
Making coffee at home
Choice magazine recommended that it was more important to buy fresh ground coffee than how you prepared it. They stated that using most supermarket pre-ground packed coffees in an espresso machine gave about the same standard coffee as using freshly ground coffee in a plunger.
If you do insist on buying vacuum packed supermarket coffee, then choice recommends Café Aurora Medaglio D’oro. It is, thankfully, also one of the cheapest! No frills rated 10th out of 28 coffees, most of which were much more expensive. Vittoria Natural Decaf came out the best decaf in terms of price and satisfaction. Lilly Decaf came out best decaf overall, but is really expensive, packed in nitrogen gas.
Apparently we should not place coffee grinds down the sink, as they are organic matter, and can corrode pipes and cause environmental damage. It is best to compost them or put them in the bin.
Choice informs us that today’s decaf is just as satisfying as standard coffee. Apparently some evidence exists to link caffeine containing coffee with a decrease in the rates of type 2 diabetes. Of course overindulgence has the well know side-effects.
If you are using a plunger, then use a coarser grind, and leave the coffee 3 minutes before plunging. Drip filter coffee should have an ‘extraction’ time of around 5 minutes, and is ground finer than for the plunger.
Sometimes when I'm travelling and I don't even have a coffee filter and holder, I make coffee according to what East Germans call the ‘Turkish’ style. You simply spoon ground coffee directly into not quite boiled water (to maintain the oxygenation of it) and stir vigorously. Leave the coffee grounds to settle a few minutes and drink. The stirring produces a centrifugal effect, making the grounds ‘heavy’ and therefore sink to the bottom of the cup. Just don’t drink the last mouthful, or you will get a mouthful of grounds!
I wonder why none of the coffee retailers, Tchibo included, don't pack coffee in smaller portions. A single person won't get through a 250g package of coffee quick enough for it to remain fresh. 100g packages would be much better. I wonder if the packaging costs would be too high, or if the coffee retailers have more 'sinister' motivations? The alternative is to share your coffee with a friend. Each of you can alternately half your coffee packet each week, so neither of you have to drink 'stale' coffee. Could this be the higher motive of Tchibo after all?
Copyright 2002 Markus Heinrich Rehbach All Rights Reserved
