1) Grinding too much coffee
Freshly ground coffee will give the freshest, richest tasting espresso and having a good quality burr grinder is an important part of your home coffee setup. Unfortunately people often defeat the purpose of having a coffee grinder by grinding too much coffee and then using the excess coffee for their next coffee making session.
A common mistake is to grind too much coffee into the doser of the coffee grinder, where it goes stale. This is one of the key advantages of using grind-on-demand coffee grinders for home use; coffee is directed into the filter as it is ground leaving limited ground coffee left to oxidise between coffee making sessions. Another bad habit is grind a whole heap of coffee into a cup or bowl and to keep the excess for multiple coffee making sessions. Coffee will begin to go stale from the moment it is ground, in a couple of hours it will prduce less than satisfactory results.
Try to grind only enough coffee for the number of beverages you are making at that particular time. When you start your coffee making session, remove any "old" ground coffee from your coffee doser before griding some fresh coffee.
2) Leaving coffee in the filterholder basket
Leaving spent coffee in the filterholder will not only make you extremely unpopular with the next user of the espresso machine, leaving spent coffee in the filterholder accelerates the builtup of coffee oils and grime inside the coffee group and filterholder of your machine resulting in more regular cleaning.
After making the last espresso of your coffee making session dump out the coffee puck, re-engage your filter holder into the espresso machine and flush some fresh water through your portafilter. Flushing an empty filterholder with fresh water will remove the majority of spent coffee oils from the grouphead, shower screen, filter bastket, and the filterholder.
3) Lazy tamping
Tamping is not rocket science, but taking a bit of care when tamping your freshly ground coffee into the filterholder can be the difference between two great shots of espresso and an uneven soupey mess. An uneven tamp, a tamp that leaves the coffee puck fractured, leaves the surface uneven or simply not applying enough pressure to the coffee puck, will result in poor quality espresso. Use an appropraitely sized tamper to fit your filterholder basket and chose a tamper that is comfortable to use. It doesn't have to be a super expensive stainless aftermarket unit, even the ubiquitous plastic tamper will produce a good result used correctly. Place the thumb and forefinger on the rim of the tamper and place the shaft of the tamper in the palm of your hand. Ensure the filterholder is supported on a flat stable surface and press down firmly and ensure that your compressed coffee puck is flat and even. Remember to wipe any excess coffee grounds from the rim of your filterholder basket.
4) Leaving the espresso machine uncleaned
"What gets done now is one less thing to do later..." and "what gets cleaned now will be 10 times easier to clean now than it will be after an hour of baking on to a hot espresso machine part".
Left alone, coffee oils and milk will "bake" onto the hot parts of the espresso machine. You can see this as the brown coating on an uncleaned steam wand or the brown-black sludge that builds up in the bottom of your filterholder. Quick and regular cleaning procedures can minmise the buildup of such things. We are not talking about perdiodic cleaning like backflushing and descaling, this is simply a quick clean to ensure the machine is in the cleanest possible condition for the next coffee making session.
- Wipe the steam wand to remove all the surplus milk, if it has a frother assister remove this and wipe the steam wand below. Open the steam wand to "blow" any excess milk from inside the steam wand.
- Empty the portafilter to remove spent coffee and flush it with water.
- Brush up any excess ground coffee and dispose.
- Rinse your coffee cloths, remember to use one for wiping surfaces and one for wiping food contact areas such as steam wands and filterholders.
- Empty, wash, and clean any drip trays if they are full or overly dirty.
5) Not watching the espresso pour
It is good to watch. Whenever I visit a cafe I take an interest see how they do things and if their coffee is up to standard or not and one of the most fundamental mistakes I see is staff not watching what they are producing, especially people using volumetric machines. I have seen everything from 10 second gushes of weak under extracted coffee to 40 second over extractions and everything in between. More often than not they clearly pay no attention to the espresso extraction. Whether you are making espresso at home, in the office, for clients, or for paying customers pay attention to the espresso pour, it will tell you more about what is going on than almost any other sense.
- Slow flowing extraction indicates too fine a grind, too much coffee, or too much compression on the coffee puck.
- Fast flowing extraction indicates too course a grind, not enough ground coffee, or not enough compression on the coffee puck.
- A very light under extracted crema can indicate a number of defects including a cold portafilter, insufficient extraction pressure, too little ground coffee, stale coffee, poor quality coffee blend, or cold cups.
- A very dark over extracted crema or a very thin patchy layer of crema can indicate a number of defects including too greater extraction pressure, too much ground coffee, a dirty grouphead shower screen, or too long an extraction time.
Watch how the espresso is extracting and you will pickup when something is going awry.
6) Not tasting the coffee
Is the milk too hot? Is the milk to cold? Is the coffee we are using terrible? Is the grinder set correctly? Is the machine clean? You are not at the SCAA world finals, but your aim in life is to eliminate the negatives so that your customers, colleagues, family, friends have a pleasant coffee experience. The quickest and most accurate way to tell this is to taste what you are making. The tongue doesnt lie and you will quickly identify if you need to steam the milk a little longer, if perhaps the machine needs cleaning, or if you have bought some rubbish coffee. It is better that you pick up any defects before your customers, clients, or dinner party guests make a comment.
7) Presenting the coffee poorly
No matter how well you can prepare coffee, presenting it poorly detracts from the whole experience. Using poor quality incorrectly sized cups removes from the feeling of quality and the enjoyment of the beverage. This can be something as simple as not heating a cappuccino cup or something more extreme like having a takeaway lid that doesn't fit firmly on the cups you are using. If the customers coffee goes cold quickly or spills down them, the quality of the beverage becomes irrelivent.
No matter if you are making espresso at home, for clients in the office, or for paying customers presenting the coffee properly completes the whole experience. Select quality ceramic cups for capuccinos and flat whites, glasses for caffe lattes, and demitasse for espresso and macchiato. Latte bowls are a fad which I am pleased to see is slowly dying and of course mugs are only good for hot chocolate or drinking filter coffee.