Coffee:The barrista as alchemist. Making the perfect cup of coffee

Guide to making good coffee

Markus´coffee guide

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 :

The Barista as Alchemist

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. Regular customers have been known to walk past their favourite café if ‘their’ Barista is not on duty. As 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%.

The ‘shot’

A single shot of espresso is the basis of all further coffee based drinks. The simple shot of espresso is perhaps the least forgiving of coffees, there being no milk or flavourings to compensate for any faults. It is therefore key to the Barista’s trade, to be able to reliably produce a great shot of espresso. The Barista must constantly hone their skills in order to be able to produce a great coffee under pressure!


Keep all cups and glasses warm by storing them on top of the espresso machine. Keep the group handles loosely attached to the group head at all times, to keep them warm. The glass or ceramic cup should not be too hot to hold. Coffee should be served and consumed immediately, to gain the full aroma and flavour, while being careful that it is not too hot. When making coffee at home using a filter or plunger, the water should not be allowed to boil, as this can de-oxygenate the water.

A continual cleaning routine must be automatic

It is not enough just to ‘back-clean’ or ‘back-flush’ at the end of the day. Coffee oil goes rancid. This rancid flavour can ‘spoil’ any beans added to the ‘hopper’, which feeds the beans down into the grinder. Therefore clean the ‘hopper’ at least twice a week with a weak detergent, and wipe daily with a brush, dry cloth, or paper towel. At the end of the day empty the hopper and run the grinder dry until all the grounds already in the grinder are fed through, and all you hear is the grinding plates grinding against each other.

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, as washing it 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 it to the group head and run hot water through for a few seconds while agitating it, moving it 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’ by allowing steam to run through it for a few seconds before every use. This removes overheated water and any milk that may have been forced back up the nozzle. It should be wiped clean with a cloth after every use.

Don’t hang tea towels or cloths on the machine, as this will keep them warm, and ideal breeding grounds for bacteria!

Roasting and Caramelisation

The heat applied during the roasting process initiates chemical reactions which produce aromatic oils. This heat produces some acids and breaks others down, unlocking the flavour and aroma of the raw coffee bean. this process is known as ‘caramelisation’ . The water soluable oils produced account for the flavour and aroma of the coffee. Different roasting times produce different aromas and flavours.

The Grind

Once you have set the ideal grind calibration on your grinder, various factors can make it necessary to adjust it. You will have to monitor the coffee produced. Humidity and temperature changes can make it necessary to re-calibrate your grinder.

As the grinding plates in your grinder age, they wear out, and lose their edges. They must be kept sharp as blunt grinding plates produce heat which can ‘burn’ the coffee.

The key to espresso is Extraction

There is a reflexive relationship between grind, duration of extraction, water pressure, and tamping pressure that you must master.

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, pushed down, with the ‘tamper’.

Make sure the group handle is attached firmly to the group head. Push the handle hard to the right, 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.

Espresso machines are engineered to produce constant water volume and water and pressure for a double group shot. Theyare tuned or alibrated for a double shot.

This explains why you don’t simply use half as much coffee to make a single as a double, as some people naively believe. It is a matter of mechanics and physics. Given that the water flow and pressure is constant, we can only adjust the quantity of grinds and the tamping pressure we apply 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, either 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. It would be more hygenic to use a metal ruler, wiping it across the rim making the heap level with it. 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, for reasons previously mentioned. The rim of the basket should be brushed free of grinds, so that the group handle can seal with the group head, and any remnants on the group handle don’t get ‘over extracted’ or ‘burnt’, adding unwanted bitterness to the espresso.

There are a number of signs to look for, and in the case of milk frothing, to listen for, when adjusting 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 and 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 like a ‘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.


The ‘crema’ is responsible for 90% of the aroma of espresso. High temperature and pressure caramelise the sugars naturally present in the roasted coffee, aerate it, and expel it along with the espresso. It should be thick, creamy, stable, and preserve the coffee flavour, aroma, and temperature.

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’.


Check the pump gauges continuously. While the machine is running the pressure should be between 8 and 9. The Tank pressure should be between 1 – 1.3 bar. It should return to this optimum after the shot and milk are prepared. If it is not operating within these ranges, then you need to contact the people who service and maintain your machine.

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.


Robusta is the cheaper bean variety. It is blended with Arabica beans to provide a richer crema and greater complexity. Robusta beans are higher in caffeine than Arabica. Most instant coffee is Robusta, therefore instant has more caffeine. Instant coffee prepared from Robusta beans is also higher in caffeine content than coffee made from ground coffee, whether brewed, plunger, or Turkish style (i.e simply stirred into hot water and left a few minutes to settle), simply because in the case of instant coffee, the entire bean is dissolved in the water and consumed. Instant coffee represents the absolute maximum extraction possible. Of course the greatest caffeine ‘hit’ can be obtained by eating the roasted coffee bean whole. Coffee beans coated in chocolate are available for this purpose. Yum!

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.

The art and science of milk preparation for ‘latte’ and ‘cappuccino’

The milk temperature should be 5 degrees. The higher the fat content, the richer the ‘meringue’ foam you can produce, and the easier it will be to attain the desired ‘meringue’ consistency. Soy also foams well. The fat content of milk is determined not only by the stated content i.e full fat 4%, low fat 1%, but by other factors such as whether the cows are weaning, the season, and the use of anti-biotics. A brand of milk is now available which is ‘designed’ specifically for use by Baristas. Skim milk froths easiest, but higher fat milk gives a richer texture. Skim milk is therefore easier to work with, and more forgiving.

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 used only for this purpose. 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. Practice 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 meringued milk foam will be shiny, glossy, thick, and dense, with really compact foam.

Serving suggestions

The fundamental basis for all coffee drinks is the shot of espresso. It can be served black, in a warmed ceramic cup. It is traditionally 30ml.

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 meringued milk 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 meringued milk 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 is traditionally added to espresso, to help reduce the natural bitterness of coffee. I also add a little  salt, as my fluid intake is so high, I need to rebalance my electrolyte intake to compensate.

Making coffee at home

Choice magazine had home espresso machines tested. Based on its report I recommend the Café Roma, ESP6 (black and steel finish) and ESP8 (all steel finish) as the best on the market. You can find them for $149 and $180 respectively in many retail stores. The home grinders recommended by choice were not available anywhere. They were both Swiss brands, and retailed at $169. You can of course negotiate or find better prices!

Choice magazine stated that how recently the coffee was ground was more important 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. So if possible buy freshly ground coffee, or grind the beans yourself.

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. Some evidence also exists to link caffeine containing coffee with a decrease in the rates of type 2 diabetes. Coffee is also higher in free radicals than tea, so rather than produce wrinkles, it may actually slow down the ageing process, and improve  our resistance to, and recovery from, dis-ease.

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 simply spoon ground coffee directly into not quite boiled water and stir vigorously. The stirring makes the grounds ‘heavy’ via a centrifugal effect, so they sink to the bottom of the cup. Just don’t drink the last mouthful, or you will get a mouthful of grounds!

Most coffee retailers 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 halve your coffee packet each week, so neither of you have to drink ‘stale’ coffee. Could this be the higher motive of coffee suppliers after all, to bring people together?

Update: I have noticed some coffee brands ARE now selling 100g soft bags of ground coffee.

©Copyright 2006 Markus Heinrich Rehbach All Rights Reserved