Points to Consider When Buying an Espresso Machine
What is meant by Bar Pressure?
A good ‘crema’ on your cup of coffee will be achieved with good bar pressure- this is the speed that steam meets your coffee grounds. A bitter taste will result if this speed is too slow. Whilst some say that with correctly ground beans 9-11 bar pressure is enough, most agree that 15-19 bar is the optimum.
What is ‘Crema’?
The rich, creamy ‘crema’ of an espresso coffee is the pure coffee extract you find on the top of an espresso, (a little like the head you’d find on a beer). It is a combination of emulsified coffee oils and tiny bubbles of carbon dioxide, trapping the all-important Volatile Organic Compounds that are the key to the exquisite aromas unleashed when you taste the espresso coffee. You need pressure to achieve this extraction as without it you are merely brewing the coffee.
If the crema is lacking or the espresso coffee is extracting too quickly (and assuming that the espresso coffee is fresh enough) you could try: adjusting the coffee grind size finer; using a little more coffee; applying a little more pressure in the tamp. If problems still exist, it could be that the machine is operating at an incorrect water temperature or pressure.
Test your crema by putting a little sugar on the top – you will have succeeded if this takes a little time to fall to the bottom of the cup!
What is a Thermoblock?
A Thermoblock (or thermocoil) is a heating element that ‘flash heats’ the water. Water is drawn from the cold water reservoir and passes through the heated thermoblock and delivered on demand. Thermoblock steaming is achieved by raising the temperature of the device even higher and having the pump deliver small bursts of water that are again passed through the thermoblock and heated into steam. The advantage of a thermoblock system is that it heats up very quickly and espresso or steam production is not limited since the thermoblock is always hot.
What is a Portafilter?
The portafilter (or group handle) holds the tamped puck of ground coffee in its filter basket (ideally this is kept warm) and is attached to the group espresso machine. Basic models have aluminium portafilters but the more expensive have brass holders which retain heat for longer. The handle of the portafilter is generally made of plastic or wood. Keeping the portafilter/basket scrupulously clean is essential.
What is the Valve?
Valves, whether mechanical or solenoid, control the water pressure at the point of delivery and also shut-off after extraction has finished.
Why does the Wattage matter?
If you are making several espressos at a time you will need a high wattage machine as the water is boiled faster. If you only make the occasional drink then this is not so important.
What does ‘Tamping’ coffee mean?
Tamping is the compacting of the ground coffee in the portafilter prior to brewing and is an influential step in determining the excellence of a cup of coffee.
With firm and even tamping, the water has no choice but to flow through all the coffee uniformly and if your grind is right and you are using a good quality espresso machine, your will achieve the best the coffee has to offer. Uneven, light tamping will cause the water to run through channels and under-extract the coffee, leaving the taste bitter and astringent. Over-tamping will cause the water to take too long to go through.
Having dosed the proper amount of coffee into the portafilter basket, level it out so that it has an even distribution in the basket. (It is easiest to rest the portafilter on your counter-top and always use a flat-faced tamper which gives control to the strength of your tamp) Firmly tamp flat down on the inside of the basket working around in about 3-4 tamps to compact the grounds evenly. Any “high” points will result in areas more compacted than “low” points after tamping, so it is important that the coffee be packed full and level in the basket. Never tamp and then tap the side of the portafilter, this will undo your careful work and cause channels and cracks.
(If you want to critique your tamping skills, examine the spent coffee in the basket after brewing looking for ‘worm holes’ which is a sure sign of channelling where the water found a weak spot. After brewing the knocked out grounds should form a dry puck – if it’s wet and mushy, the grind and the tamp were off!)
Which is the best milk to use for Frothing?
Any type of milk – whole, semi-skimmed or skimmed – is fine for frothing as long as it’s fresh, any more than four days and its best not to use. Most baristas however, would choose whole milk because the fat content is neither too much or too little to achieve an ideal balance of taste and texture when mixed with coffee.
A stainless-steel jug (which conducts heat better) should be used for milk-frothing, filled to just under half with cold milk. The froth is ready when the base is too hot to touch. To get rid of any bubbles, give the jug a couple of taps and then spoon the froth onto your espresso.
How do I make the perfect cup of Espresso or Cappuccino?
Espresso coffee is seen as the very essence of coffee – an intense hit of pure coffee indulgence using around 25-30ml of water. However, it has often been the case the some of the world’s very finest coffees become distorted when using this method – in particular it intensifies acidity thus making a pleasantly acidic coffee unbearably tart. For this reason blends have histroically been developed for espresso to combine the finest elements from each of a number of coffees.
However, things are changing and through experimentation with different coffees available, roast styles and set up, we’re seeing single farm or estate coffees being used on their own as espresso coffees.
For the very best results please follow the manufacturer’s guidelines, as each machine varies.
Follow these tips for your perfect espresso or cappuccino:
- It is preferable to grind your own espresso beans for this method, but otherwise use ‘espresso grind’ pre-ground coffee.
- Ensure that your coffee is very fresh otherwise this will impact on the quality of the espresso coffee from extraction to crema, and from aroma to taste.
- However there is one thing to note, coffee can be too fresh for espresso!Within the first week after roasting, the extraction can be bubbling and foamy and the taste of the espresso skewed and ‘hard’.Espresso coffee blends often need a week or two to settle after roasting.
- This coffee requires a very fine grind-size because the contact time between coffee and water is so relatively short.It will vary slightly based upon the equipment used and other factors such a freshness of the coffee.
- Ideally, a high water pressure (around 9 bars) is required for the best extraction of espresso coffee, as you’re trying to extract all the very best elements from the coffee and avoid any of the negative characteristics.
- Ensure that the machine is fully heated before use and that cups to be used are warmed through..
- You will need at least 7g of finely ground coffee for a single espresso, and minimum of 14g for a double (depending upon how much your portafilter will allow).
- Next, fill the portafilter with the coffee and tamp the coffee down, applying enough pressure to ensure that the coffee has been compressed evenly. The grounds need to be compacted evenly so that the water flows through evenly – otherwise at pressure, water will find the route of least resistance and lead to a very inconsistently extracted espresso coffee.
- Press the correct button (see manufacturer’s guidelines) to begin extraction. If every factor is working in tandem, a rich espresso coffee with a thick ‘crema’ should have been delivered in around 25 seconds.
Espresso coffee can be used as the base for the following drinks:
- Cappuccino – adding steamed and foamed milk to the espresso coffee.
- Café latte – adding steamed milk and a touch of foamed milk to the espresso coffee.
- Macchiato – adding a touch of foamed milk to an espresso coffee
- Americano – adding an espresso coffee to hot water to make a black espresso coffee
What is the difference between Plate and Burr grinders?
Burr grinders use burrs to crush coffee beans to a particular size and can be plate burrs or conical burrs – both achieve the same goal in grinding and both produce high quality grinds. Conical burrs grind the beans slower and produce less heat which can result in less loss of flavour in the beans due to vaporisation of the bean’s oils.
Blade grinders use spinning blades to chip the beans. The size of the grind is dependent upon the time you leave it grinding and can also be subject to spoiling the bean by overheating.
Why clean or descale my Machine?
Your coffee machine’s number one enemy is limescale, especially if you live in a hard-water area. Limescale develops every day and can, over the long term, affect the taste of your coffee or even stop your machine working properly.
You should make sure you use a descaler, cleaning product and/or cleaning tablet on a regular basis (a minimum of every 6-8 weeks). Tablets are the easiest to use, as they can be simply dropped into the water tank before you run the machine’s cleaning programme or its regular programme without coffee.
Water-filter jugs are a great way of avoiding limescale and chlorine getting into your water tank. However, using a filter jug doesn’t relieve you of the task of regularly descaling your coffee machine.
Are Auto-Frothers difficult to clean?
Auto-frothers are extremely simple devices to clean as no milk is actually drawn into the machine. To clean, all that is required is for water to be drawn through the hose after a certain number of coffees.