Brewing Guide to Espresso Machines
This is the basic technique to brewing espresso with an espresso machine. Once you have mastered this you can then start to experiment and find your very own 'Espresso Nirvana' .
Use filtered water in your espresso machine. Water from the tap may contain particulates (such as dirt, sediment and rust) that can affect the taste, texture and aroma of espresso. Particulated water also causes added wear on parts; and can clog solenoids, valves and groupheads.
You should aim to complete all these steps as quickly as possible, but it is important not to rush any stage, particularly the tamp.
Basic Espresso Brewing Method
1. Fill the water tank of your espresso machine with filtered water, attach the portafilter (empty at this stage) and turn on the machine. Wait for the machine to warm up.
2. Switch on the espresso function (pump) and allow hot water to pour through the portafilter for between 10-20 seconds. This will ensure that the grouphead and portafilter are hot.
A small variation in temperature can make the difference between a great espresso and a passable one, so it is very important to ensure that every part of of your espresso machine and the water inside it are at a constant temperature.
3. Remove the portafilter and quickly wipe dry with a soft clean cloth.
4. Grind your coffee beans and dispense 7 grams of grounds (14 grams for a double shot) into the portafilter basket. Use a finger to brush the grounds around in the portafilter to level them as best your can.
5. Use a coffee tamper to press down the coffee grounds into the portafilter basket to form a tight puck. You should apply 30lbs/13.6kgs of downwards force to avoid 'channelling'. As you remove the tamper, twist it 360° to leave the puck with a polished surface.
The concept behind tamping is: to ensure that the grounds are evenly distributed in the basket; and that there are no tiny air pockets. The tamp is very important as water always seeks the path of least resistance; so if you tamp too lightly or not at all, the water will find the areas where there are least grounds and channel through them. These areas will become over-extracted and release bitter compounds into the espresso, whilst the rest of the puck will be under-extracted, leaving behind much of the flavour. To work out exactly how much pressure to exert, practice by tamping the portafilter on some bathroom scales.
6. Attach the portafilter back onto the machine and switch on the pump. It should take between 25-30 seconds to produce a 1.25oz/35ml shot (or 2.5oz/70ml for a double shot).
If the shot volume is less than 1.25oz after 30 seconds, adjust your coffee grinder to a slightly coarser setting; and if the shot volume is more after only 25 seconds, adjust your grinder to a slight finer setting. It will take several attempts with a new grinder to get it dialled exactly right for your espresso machine.
N.B. The level of moisture in the coffee grounds affects the flow-rate of espresso, as the higher the moisture content the tighter the grounds will pack. As different espresso blends contain different levels of moisture you will need to adjust the settings on your grinder accordingly. Also as coffee is hydroscopic (it absorbs moisture from the atmosphere) it is, therefore, a good idea to regularly monitor the flow-rate of espresso, even if using the same blend, as changes in humidity may need to be compensated for by altering the grind slightly.