Things to investigate and adjust to get your espresso tasting perfect to your taste.
I created a quick list of possible issues that can cause your coffee to taste more bitter than you like or expect, followed by a more detailed explanation and a rule of thumb to aim for.
- Over extraction
- Too much water
- Water to hot
- Grinding gone wrong
- Not the right bean or roast
- Old coffee beans or grind
- Dirty equipment
- Bad Water
Too much water
Too much water causes over extraction and the bitter compounds in the grind which dissolve slower get pulled into your coffee.
Rule of thumb: Pull twice the size of coffee out as the amount of grind.
For 18 grams of grind use 40ml to get your 36ml (=36gr) espresso.
Water too hot
The hotter your coffee the easier it becomes to dissolve the components in the coffee grind, including the bitter components.
Rule of thumb: Aim to use water at 94 degrees Celsius.
The Pull took too long
Bitter components release slower than most of the other components in a coffee grind.
When you pull the water through the coffee grind, more and more bitter components dissolve and end up in your coffee.
Rule of thumb: Do your pull in around 28 seconds.
The type of coffee roast
The darker your coffee roast, the higher the concentration of bitter components. Try a lighter roast if the coffee is too bitter to your taste.
Rule of thumb: the darker the roast, the more bitterness you may expect.
Grinding gone wrong
Too fine grind causes over extraction and the bitter compounds in the grind get dissolved more easily and pulled into your coffee.
It is difficult to measure the coarseness of your grind.
Rule of thumb: 1 use your eyes to observe the coarseness and also feel the coarseness by taking a pinch of grind and rolling it between your thumb and finger. 2 If you can measure the pressure of your pull there is a rule of thumb. A pressure buildup of 9 Bar indicates the grind is of a good coarseness.
Old grind or coffee beans
Your coffee beans or grind is not fresh
Over time beans lose their freshness.
Once beans have been roasted they will interact with air. The most volatile components release the quickest. Most bitter tasting components are less volatile. Thus older beans and grind will have relatively more bitter tasting components.
Because of a bigger surface area exposed to the air, grind loses its freshness faster than a bean.
Rule of thumb After opening a sealed pack roasted beans last maybe a month and ground coffee a week.
Your container, grinder, espresso maker and tools should be clean. When you leave coffee beans, grind or sediment behind on any of material or tools to make your espresso you contaminate your pull. Clean and maintain your tools.
Rule of thumb: Clean and dry as much as you can between pulls, a good clean by end of day and a thorough clean every week.
Tip: Also remove your basket once in a while from the handle and clean them separately.
You could have water coming out of your tap that makes your coffee bitter. An easy test is to make your coffee from a bottle of water you buy in a shop. Any taste difference implies that there might be something wrong with your water. Filtering your water might solve that issue.