There is nothing worse than the disappointment of a bitter cup of coffee.
Coffee has natural bitterness due to its caffeine content, but only about 10-15% of bitterness is due to the caffeine. A low level of bitterness actually helps tame coffee acidity. However, we recognise that overpowering bitterness or unbalanced coffee is disappointing to the consumer. So why is your coffee bitter? Perth’s best coffee enthusiasts will tell you the bitter taste left in your mouth is often a result of one or maybe even a combination of the following three things:
1. Over extraction
When we brew coffee, the flavour hinges on the extraction of solids from the coffee itself. The total dissolvable solids, along with the evenness of extraction determines just how good your espresso tastes.
Brew ratio is all about getting the balance between the amount of ground coffee and the amount of water used correct. Not enough water results in sour, under-extracted coffee, and too much water results in bitter, over-extracted coffee. The espresso ratio we recommend is 1:2 (coffee:water).
Volumetrics and coffee machine programming
Checking the volumetrics on the coffee machine is part of our daily set up. Volumetric programming ensures our coffee machine is dispensing the correct amount of water for the dose we are using. We recommend that baristas weigh their yield of espresso to ensure consistency. As always, weighing your dose is a crucial step in maintaining your brew ratio and making the best coffee.
2. Grind Size
Just as brew ratio affects espresso extraction, the grind size of our coffee also plays a huge part in the overall taste of the coffee.
Using a grind setting that is too fine or too coarse will significantly alter the flavour of your espresso.
Espresso that pours too fast results in under extraction. Espresso that pours slower becomes stronger in flavour as the coffee solids have more time to dissolve – but only up to a point. If the shot pours too slowly due to the grind being too fine, the espresso will taste bitter. You need to make your coffee grinds coarser so that the water is not so restricted.
Espresso should pour between 25 – 35 seconds, with the best results usually found between 27 – 33 seconds.
3. Dirty machine and equipment
This is a no brainer.
DIRTY EQUIPMENT = BAD TASTING COFFEE
If oils are not removed through regular cleaning of your coffee machine, then they will go rancid.
Metallic, bitter or astringent flavours in coffee are commonly blamed on the barista or the coffee beans. In actual fact, they are often caused by dirty equipment.
We often hear that a machine with low usage does not need to be cleaned with the same frequency or care that a high volume machine does. This is simply not true. An inactive coffee machine will build up oil just as quickly as a frequently used coffee machine. This is due to the increased idling time; with no water to pass through the various parts, oil is allowed to build up quickly.
If your net showers and group head assembly become blocked with coffee oils, the water flow is restricted. This leads to channeling and uneven extraction. Not only does this cause bitter tasting coffee, it puts stress on vital parts of the coffee machine (like the solenoid and the pump). This causes unnecessary and avoidable wear and tear.
Backflushing your coffee machine
We recommend that you backflush your coffee machine with plain water as often as possible throughout the day. At the end of the day, backflush each group head with specialised coffee machine cleaner.
Dirty portafilters and baskets can also cause coffee to taste ashy and bitter if not cleaned properly. You should regularly clean these parts during service. Give them a good soak in hot soapy water at the end of the day, before scrubbing, rinsing and putting back into the machine.
Don’t forget your coffee grinder!
Doser coffee grinders need to be thoroughly cleaned from any excess coffee grinds. Additionally, coffee beans need to be returned to an airtight container or bag overnight. Find more coffee storage tips here.
Some other things to consider:
- Ensure the coffee beans you are using are fresh. 1-2 weeks after roasting is recommended.
- Try a lighter roasted coffee.
- Check your water is of good quality. Water filters should be changed regularly. Make sure that the temperature is not too high; optimum is between 92 – 96 degrees.
If you would like more information regarding any of the above issues, check out our barista training classes. We cover detailed coffee preparation and how to implement an espresso recipe. You will be making some of Perth’s best coffee in no time! Book online or contact us firstname.lastname@example.org
– Summah (Barista Trainer)