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Espresso Brewing Guide


October 24, 2016

Espresso Brewing Guide


Introduction

Baristas working in cafes the world over look for the perfect espresso in every cup, but they don't always get it due to the volatile nature of the ingredients and the number of process variants in the making, some of which are out of the barista's control. 

The problem is that just one poor quality input can result in your espresso being undrinkable. Until you get 10 out of 10 quality inputs you will not even get close to a 100% quality output. 

Getting the perfect espresso is a far greater challenge for the home barista. Here are the 9 areas you need to master to get there..

1. Select the right espresso machine
2. Select the right grinder
3. Meticulously maintain the equipment
4. Use the purest water
5. Select quality coffee beans
6. Maintain the freshness of the coffee
7. Create the perfect resistance
8. Get the pre-extraction settings right
9. Get the timings right


1 - Select the right espresso machine

The Italians have a long and inventive history in espresso coffee machine manufacture, starting with Angelo Moriondo's invention in 1884. It is any wonder then that they still dominate this market with the most respected brands like Rancilio, Dalla Corte, La Marzocco, La Cimbali, Faema, La Spaziale, Wega and Nuova Simonelli all being made in Italy. 

2 - Select the right grinder 

While all 10 quality inputs are critical for extracting 'the perfect espresso', I personally think that the right grinder is the first among equals. Here's why! Your grinder needs to be a slow rotating, deep seated, conical burr grinder with a powerful motor that can consistently deliver into the portafilter, finely ground coffee that is measured to a precise volume. The best Mazzer grinders from Italy fit these requirements admirably. 

3 - Meticulously maintain the equipment 

Few people realise the speed at which the burnt caked-on coffee residue can build up in an espresso machine will destroy any chance you might have had at 'the perfect espresso'. Keep it clean!!!

4 - Use the purest water 

Given that water constitutes 95% of an espresso shot, some attention should be paid to its impact on the espresso outcomes. The quality of the water that the espresso machine connects to, can have a detrimental impact on both the espresso taste and the brewing equipment's performance and reliability. 
Water as ‘the universal solvent’ takes up airborne gases and industry air pollution as it falls and then dissolves the naturally occurring calcium, magnesium and iron in the soil and carries dirt in suspension as it soaks through the ground. Public water authorities remove most of the dirt particles and add chlorine to make the water safe to drink. But to produce the best espresso, water filters (left below) are needed prior to the water entering the espresso machine to remove unwanted suspended material and the chlorine.

Water hardness (the amount of calcium and magnesium in the water) is another issue that needs to be considered in pursuit of 'the god shot'. Now while up to 90 parts per million (ppm) of these minerals in the water can enhance the espresso taste, above this concentration there are no noticeable flavour benefits yet at 150ppm (8.5 grains per gallon) and above, a significant build up of calcium scale in the coffee brewing equipment can occur, negatively affecting its performance. 
A water filter will not remove these minerals so you also need to connect a water softener to the water supply (right above), which replaces the calcium content with sodium. 

5 - Select quality coffee beans 

Quality coffee beans means selecting a premium grade of the right coffee species from the right country/estate and roasted to the optimum level for espresso coffee making. All coffee-bean exporting countries grade their coffee beans for quality but they don't all use the same names or ascribe the same meanings to similar grade names. Premium grade is usually determined by a combination of known taste enhancing factors primarily classified by large size, heavy density and a minimal number of defects (5 or less full defects in 300 grams of coffee beans). Without a doubt, the wet processed Speciality Grade, Arabica coffee species that is dark roasted, produces the best espresso tastes and should be your bean of choice in your pursuit of 'the perfect espresso'


6 - Maintain the freshness of the coffee 

The most delicate and flavoursome compounds in coffee beans are lost with even the most minimal exposure to the moisture found in ambient air. Moisture causes the aromatic compounds in coffee to oxidise and so destroying the fine aromatic tastes and replacing them with rancid ones. 

Furthermore, once ground, these most prized aromas in the coffee are lost soon after the grinding process if not used within 15 minutes. These compounds give coffee its sweet, caramel, “butter-like”, fruit/floral-like aromas, however they are easily oxidized (changed into acid and water) or dissipated (into air) especially when subject to the grinding process.


So for your best chance at 'the perfect espresso', roasted coffee beans must be kept in a sealed one-way-valve bags in transit, stored in a cool dry place in air-tight opaque containers when removed from their transit bags, placed in minimal lots in the coffee grinding hopper and used immediately once ground. Always buy beans and grind yourself.

7 - Create the perfect resistance 

The perfect resistance is where the pressure from the espresso machine's pump only just wins the battle when confronted with the resistance of a tightly packed finely ground coffee filled portafilter basket. The closer you can manipulate the elements to create the perfect resistance, the better your chance of extracting 'the god shot'. 
On one side of the perfect resistance is a powerful volumetric pump set to 9-10 bars of pressure when extracting. On the other side is the fineness of the grind, the amount of ground coffee, the compactness of the two in the portafilter basket and the pressure you are able to exert on the ground coffee as you engage the portafilter with the espresso machine. 
You will know that you have the perfect resistance when an extra half a teaspoon of ground coffee causes the pump to stall and the lights on the espresso machine to flash. The coffee extraction from the perfect resistance will be delayed 3-5 seconds after pushing the button, start by dripping slowly in a thick honey-like density, build to a mouse-tail look as the espresso extraction curls under the portafilter spout and thins as it falls.


8 - Get the pre-extraction settings right 

There are many seemingly insignificant things that an expert barista will do when preparing for a potential 'god shot', which are explained in detail here ... What attributes set a great barista apart from the run-of-the-mill? 


They will flush hot water through a rotating empty portafilter in the group head to clear away spent coffee grains from the group head gasket, the group shower and the portafilter basket, they will wipe the filter basket dry and remove all traces of previously spend coffee grains from the portafilter rim, they will flush water through the shower-head again to reset the temperature at the shower-head to the optimum level for perfect extraction, they will attend to the gauges to ensure that both boiler pressure (temperature) and pump pressure are optimally set and ready and they will wipe excessive new coffee grains from the rim of the portafilter as they create an impenetrable seal with the group head in the espresso machine. 


9 - Get the timings right 

Timing is a vital part of extracting 'the perfect espresso' and the expert barista is attentive to them all. From the time that the coffee beans were ground, to the time it takes  to serve the espresso to the customer. The expert barista is seeking the minimal time at each of these touch points to maximise the potential for the perfect espresso extraction. 
But by far the most important timing is the length of the extraction time and identifying the optimal time to stop the process. An expert barista knows that the perfect time to finish the extraction is when the total available flavours of the ground coffee have been extracted yet seconds before the tanic acid has had a chance to breakdown from coffee shell and leach into and destroy the cup with its bitter, burnt and astringent aftertaste. You know you have gone too far when the rich dark caramel creme changes to a lighter straw colour extraction.

Practice 

The 'eye of the barista' is developed from studying the cause and affect results from tens of thousands of espresso extractions. A great barista can accurately rate an espresso coffee taste purely on the look and form of the extraction. We know this is a detailed guide but read through and take the advice you can and apply it to your home scenario.

Get the Brew On




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