These tips probably apply more to a commercial environment than a domestic one, but hopefully there are some useful reminders for anyone in here.
We’ve all ended up drinking espresso, somehow a delicious espresso remaining elusive. These may seem obvious but all get overlooked from time to time.
1. Plan for palate fatigue
Palate fatigue is inevitable, and too much coffee doesn’t just change and dampen your ability to discern flavours – it also quickly affects your enjoyment of coffee too. David Schomer made a very good point once – coffee never tastes better than when your body really wants it. We can often be a lot more forgiving of flaws when drinking that first cup that we really want. The opposite is true for me also. After too much coffee nothing tastes good. When my body has had enough caffeine an espresso may be technically correct but I won’t find it delicious. At this point continued tasting is not particularly useful.
Scott Rao recommends not just spitting the espresso you taste, but also rinsing immediately afterwards with water. This is pretty much the best way I’ve found. Drinking less coffee slows my caffeine ingestion, and the rinsing slows general palate fatigue.
2. Don’t overreact
Frustration dialing in a grinder often leads people to react too quickly to a bad shot. Making sure that you’ve isolated the problem before making a change is very important. All too often a shot will run fast and a barista will immediately change the grind a little finer. The next shot runs too slow. Double check before making a change, because everyone makes mistakes – an accidental underdose for example.
Even the best grinder in the world retains quite a lot of ground coffee. Most visibly in the throat between the burrs and the dosing chamber, but also in the dosing chamber as well. Every grinder benefits from a decent purge – 10g to 15g is plenty. Consider it an investment in the next shot, rather than a waste. Ending up with a dose made up from a mixture of grind settings is not a good thing.
4. Taste tells you everything
It won’t always point to the problem, but the balance of the espresso will give you a pretty good idea of what is wrong. Unbalanced, dominant acidity coupled with astringency points towards underextraction. It could be a number of reasons – pour too fast, temp too low, shot volume too short – but you can be pretty confident that you haven’t taken enough from the coffee. An excessive, dominant bitterness and an unpleasant finish will usually point to overextraction.
5. Take a broad sampling
When you are dialling in things like brew temperature this is incredibly difficult to do from only a few espressos. Tasting more will allow you to get a better idea of what is wrong. Little mistakes made from shot to shot can easily obscure bigger problems. I don’t feel confident about saying a brew temperature is wrong until I’ve experimented with a number of other things first.
Shared from Jim Seven (http://www.jimseven.com/2009/12/12/7-tips-for-dialling-in-an-espresso-blend)