Bitterness is the peculiar sensory characteristic of coffee. But why is coffee bitter and why do we like this typically unpleasant taste in our favorite drink?
Talk to professional baristas and they will tell you that the only way to make true coffee is via an espresso coffee machine.
The word “espresso” springs to mind when we talk about pressure brewed coffee.
Defining the espresso
Espresso coffee is the result of extraction that takes place under pressure and involves a certain amount of water and ground, roasted coffee.
Thanks to Italian technology, espresso stands out since it seizes a real concentration of aromas and flavors from the beans.
It’s not pure chance, in fact, Italian espresso is appreciated more and more around the world.
Its crema, aroma, body and flavor are the unmistakable characteristics that distinguish it from other methods. It’s an art that is truly made in Italy.
Using about fifty beans of roasted coffee, finely ground and putting hot water through them at high pressure, we not only obtain the much loved black beverage, but also a concentrate where thousands of aromatic substances burst out, to make espresso unique. Moreover, the sensations it offers do not end in the moment it is tasted, but persist for a long time.
The espresso supply chain is by no means short. Many variables contribute to the cup’s final result.
It is worth recalling that 6 months elapse from the time the coffee bean is harvested to the moment it is served in the cup. The last link of the chain (preparation of the espresso the moment before serving) takes just under 6 minutes and during this brief lapse of time many variables can affect the quality of the espresso.
The espresso coffee machine
By comparison to the moka pot, an espresso coffee machine is a much more complex coffee making apparatus.
Anyone who knows anything about coffee knows what an espresso coffee machine is. It has been keeping us caffeinated since 1901!
Italy has always been the leader in espresso coffee made in Italy.
As well as in espresso coffee machines and in coffee grinders, which in the barista’s hand turn the blend into that vibrant, flavorful product so highly appreciated by consumers in the four corners of the globe.
The result is a cup of quality and this is independent of the consumer’s highly subjective individual taste or any environmental, socio-cultural and even physiological factors.
From the very outset, coffee machines have been more than a refined, technologically precise instrument. They are elegant, artistic items that are true and proper works of art reflecting the times and Italian lifestyles.
The daily habit of the breakfast cappuccino (with or without cornetto), the mid-morning espresso consumed standing at the bar, the after dinner coffee (although, when the barista is negligent, lackadaisical or unskilled, the apotheosis can become a negative experience leaving a bitter taste in the mouth, an experience to be forgotten).
There is an entire world behind the espresso coffee machine.
Superb cup quality depends first of all on extraction capacity, the machine’s ability to draw into the cup all those positive aspects of the components in the blend while leaving the negative ones behind.
Producing an espresso requires meeting precise percolation conditions, factors that affect the machine’s ability to extract the brew.
Temperature and pressure are the two key variables and thus the main pathways to innovation: one affecting the machine’s thermal stability, the other modulating its pressure. Therefore, the barista must have the full, flexible control over all water-related settings.
In order to guarantee constant quality the following come into play:
– the ergonomics that ensures total comfort, safety, health and efficiency
– the easy access to the main components of the machine, which makes it easier for the barista to maintain his equipment.
What’s it made of?
Today, espresso coffee machines come in various shapes and sizes with loads of features and gimmicks.
Some are automatic and use complex electronics for the proper brew time and water flow whereas others give the barista a little more control over the extraction process.
However, the basics are the same: pressurized water is pushed through a chamber/puck of finely ground coffee beans, through a filter, resulting in what we call a shot of espresso.
The main components of a traditional espresso coffee machine generally are:
- the water boiler which contains hot water and steam. Cold water from the water main is heated inside the boiler, thanks to the heat source (if electric, an internal heat coil).
- the heat exchanger is used to quickly bring water to a temperature of 90°C which is ideal for espresso preparation. This device is dipped in the boiler and heated from the outside through the boiler’s own hot water and steam.
- the pouring unit is the part the filterholder is clasped to. The unit is kept at a steady temperature through a continuous water thermosyphonic circulation system in order to avoid any sudden temperature drops in the device that will be used to produce the beverage.
Cold pouring units damage the final quality of espresso.
Espresso coffee machines can have from 1 to 4 pouring units.
- the pump: the public water mains generally have an average pressure of about 1-3 atmospheres; the electropump is used to rise the pressure to 9 atmospheres, so that water can seep through the layer of ground coffee and extract its substances. This device can be found inside or outside the coffee machine and can have filters to segment out limestone and other impurities.
- the steam and hot water nozzles: faucets are used to get steam to froth the milk, heat liquids and draw hot water to prepare other hot beverages.
- the filterholder is made up of a metal container where the filter is inserted (it might contain ground coffee doses to make one or two espressos), a thermally-isolated handle and one or two spouts that the extract will be discharged from.
- the control panel:
– pressure gauges (manometers): indicate the pressure of both the water injected by the pump and the one inside the boiler.
– pneumatic pressure switched: these instruments are pressure monitors located inside the machine. They maintain a constant temperature of the water inside the boiler through the inlet or the exclusion of heat (+/- pressure = +/- heat). In new concept machines, this role is performed by electronic temperature probes.
– solenoid valves set the correct flow of water or steam.
– water regulator keeps a set level of water in the boiler.
How does it work?
The boiler uses an electrical heating element that heats up the water; the heated water then heats water running through the tubes passing through the boiler (the heat exchanger). Generally, each group has its own heat exchanger.
However, heating all the various parts of the machine always depends in some way on the water in the boiler.
The new generation of espresso coffee machines
have independent groups instead of having individual water reservoirs.
The substantial difference lies in the fact that each group has its own hydraulic circuit, heating system and water reservoir for the preparation of espresso. And in the use of electronics and software.
Independent hydraulic circuits for each group means therefore that each group has its own independently heated reservoir, with its own electronic control to determine the temperature of the water inside.
The same holds for the group heads which are also heated by their own heating element and this heating is constantly monitored by a software-controlled temperature probe.
Obviously, the machine has a service boiler to provide steam and water for tea.
The brain behind all this is a true and proper computer which controls all machine operating parameters using sensors. It monitors: temperature of the group and reservoir, extraction time, coffee flow checking both rate and adequacy as it flows into the cup (using a system that checks the real flow against an ideal flow curve), humidity and self-learning system that helps manage energy saving.
Therefore, not only do these units focus on keeping the temperature constant throughout the day (+/-1°C), they also ensure a perfect cup with an utmost saving of energy (since the energy is brought to bear where it is needed, when it is needed).
The research of increasingly effective solutions is non-stop and ultimately ends with allowing the barista free rein to his professionalism, producing perfect espressos and cappuccinos while guaranteeing good results in the cup with just a few gestures.
The innovation has brought about major technological evolution. Indeed the results obtained with today’s espresso coffee machines are wonders in terms of quality of the results, reliability in time and flexibility for use.
Electronics and research into new materials with low environmental impact and greater thermal resistance, into such as yet unexplored fields as remote post-market service, still have a long way to go.
How to use it?
Espresso coffee extraction process
The filterholder containing the perfectly ground, measured and pressed roasted coffee is clasped to the pouring unit where the pre-infusion and extraction stages of the beverage will take place.
When the pouring button is pressed, the electric pump has the task of raising the pressure of the water drawn directly from the water main and sending it into the boiler through the heat exchange unit and then on the pouring unit.
Once hot water has reached its destination, the sprayhead guarantees its homogeneous discharge over the layer of ground coffee which is transformed into espresso.
Skill level required: barista
The “hand” of the barista plays a fundamental role in all of variables.
A skilled hand is essential for a quality espresso.
First of all this “hand” must choose what type of coffee to use. The choice of the right beans coffee blend and the degree of roasting affect the subsequent steps in the preparation.
The “hand” must ensure that the beans are ground properly with a grinder that is in good condition and suitable for grinding espresso and able to ensure that the coffee powder (the grinds) have the correct particle size distribution.
Then they must decide the dose to be set into the filter.
This is followed by pressing of the coffee into the filter, if possible by hand, exerting adequate pressure so the pad of coffee will be correctly compacted.
Before actually pouring out the beverage, the barista must make certain that the machine is clean and functioning properly, checking the pressure of the water supplied, its temperature and ensuring that this temperature remains constant.
Once the coffee starts pouring out, the first drops of the beverage exiting the filterholder spout should be checked to ensure that the percolation is uniform, without creating any preferential paths that would result in an under-extracted beverage.
Of course, one must not underestimate the cup that will accommodate the espresso. The material, shape, color and temperature must all be controlled before output.
And it is the “hand” that judges the final result obtained, determining the organoleptic properties of the espresso.
Independently of the culture and geographic area where this coffee is consumed, one characteristic essential to all is the absence of any defects in the cup, that can stem from the raw materials or improper preparation parameters.
This requires constant training in tasting and testing different profiles, different coffee parameters and understanding that varying water temperatures by just 0.5°C can significantly change flavor profile.
What To Expect
Resulting brew: a perfect shot of espresso!
When done right..
All too often the barista is an improvised operator without the necessary professional skills or passion. They do not realize that being a barista is a true and proper profession. It requires experience, technical mastery, knowledge of how to manage, check and maintain all the products and equipment involved in making a perfect Italian espresso.
Hey barista, warning to the under or over-extraction!
The espresso coffee machine allows to manipulate and change multiple variables including water temperature, extraction time and the total amount of coffee brewed, and so it can help to have consistency, quality and control. However, good extraction is not enough. The barista has to ensure consistency from cup to cup.
Closing thoughts about espresso…
The verdict: we prefer a good, unique espresso shot!
And what about you?