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?
Barista’s skills for the perfect espresso.
A skilled barista’s hand is essential for a quality espresso.
- choose the variety, what type of coffee to use. The choice of the right coffee bean blend and the degree of roasting affect the subsequent steps in the preparation;
- manage stock;
- ensure consistent quality.
- ensure the beans are ground properly (type of grind required: a fine, consistent grind);
- adjust the dose according to the weather;
- only grind enough coffee for the day’s consumption.
Grinding the beans
The grinder-doser is the instrument used to transform roasted beans into ground coffee. They grind the beans on demand to increase the surface that will come into contact with the hot water, thus better extracting the soluble substances.
If the coffee is properly ground, it will take between 25 and 30 seconds to extract an espresso.
If the grinds are too coarse, the water will flow through too quickly and the espresso will be under-extracted. On the other hand, if it is too fine, the water will have difficulty passing through and drip slowly from the spout and in this case the espresso will be over-extracted.
Here’s a trick of the trade: pinch your grind and observe what happens. It should clump in your fingertips. Too coarse and it won’t clump at all, too fine and it will clump excessively.
To prepare the perfect espresso, ensuring the best extraction of the substances in the coffee, the grind must be adjusted according to the texture of the beans and the relative humidity in the environment. Therefore, in damp weather, the grind must be coarser but finer when the air is dry.
The world of grinding in the last few years has seen a true and proper revolution bringing coffee blending to peak levels, exalting the aroma of coffee, taking it directly from bean to cup.
New technologies applied to coffee grinders provide a new generation of “on demand” grinders and the result is a more precise, reliable and efficient grind. The modern grinders place customized functions at the barista’s fingertips, guaranteeing utmost quality in grind.
- set the correct weight (7gr).
Then decide the dose to be set into the filter as this dictates the size of the filter to be used.
Once the filterholder is latched onto the unit, it is important to ensure that there is adequate space to allow for correct preinfusion and expansion of the coffee grinds as they absorb the water.
- correctly press by hand with the tamper the ground coffee set in the filter exerting adequate pressure so the pad of coffee will be correctly compacted.
Remember, by definition, espresso requires that the pressure of hot water supplied by the pump drops as it passes through the coffee; thus it is essential that the pad be porous enough for this to happen.
The most underrated gesture: compaction.
The preparation of the filterholder is not complete without compaction, a fundamental gesture, together with the grinding, for an espresso rich in properties and aromas.
Thanks to the press, operated in a rotary direction, a force of around 20 kg is obtained on the powder which is the perfect pressure to obtain the right resistance to the passage of water. The sensitivity of the barman is essential to perform this important maneuver.
When preparing espresso, the ability to properly and evenly press the layer of ground coffee in the filter is frequently disregarded.
If the layer of ground coffee is pressed incorrectly, water pushed by the coffee machine at a pressure of about 9 atmospheres, will flow towards only one side, where the dose is less dense and thinner. As a consequence, coffee will not be fully extracted. If the pressing applied is too light, the espresso will be under-extracted; if too heavy, the espresso will be over-extracted.
- evaluate the most appropriate water treatment system to meet the bar’s needs.
- good manual skills for preparation are essential: starting the flow through the heads and turning on the steam wand at the right moment, cleaning the filter before hooking it on, emptying out used grinds, keeping the filterholder warm and connected to the unit;
- 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.
Cup and accessories
- select the right cup.
Of course, one must not underestimate the cup that will accommodate the espresso: the material, shape, color and the temperature must all be controlled before output;
- arrange cups in a functional manner on the cup warmer;
- organize the work space.
- offer fast, clean, courteous service with a smile and well-groomed appearance.
Espresso coffee machine
- before pouring out the beverage, make certain that the machine is clean and functioning properly;
- check the pressure in the boiler (around 1 bar);
- check the water pressure during extraction (8-10 bar);
- check temperature of the outcoming water (88-92°C);
- check the condition of the heads (gaskets, sparyheads, filterholder, filter and spouts);
- ensure the extraction takes between 25 and 30 seconds, producing a volume of 25-30cc.
- check the degree of grinding;
- ensure the grinder is suitable for grinding espresso and able to produce coffee powder (the grinds) that have the correct particle size distribution;
- check the grinder for wear;
- check the dose and that the doser emits the right amount of coffee.
- check temperature of the cups.
- check water hardness and chlorine content.
Espresso coffee machine
- clean the gaskets, spray heads, filterholder, filter and spouts;
- clean the cup holder grid, drain tray and steam wand;
- wash the head with the blind filter;
- call technical services twice a year for general machine check-up.
- clean the bean container, grinder blades and doser;
- call technical services to replace worn blades.
- replace cups that are chipped or worn.
- change water in the boiler.
- periodically regenerate water softenening resins;
- change resins according to installer recommendations.
And it is the “hand” that judges the final result obtained, determining the organoleptic properties of the espresso.