Bitter coffee: Why it happens? - cafelier

Bitter coffee: Why it happens?

Bitter coffee: Why it happens?

Statistics show that 54% of Americans drink coffee every day, and our own statistics show
that 99% of people cannot function normally without coffee.
Nobody is born a coffee enthusiast. Similar to fine wine, it takes some getting used to. Even
though coffee is naturally bitter, after trying a new blend, your face might scrunch up from
how bitter it is. Instead of being an overpowering dose of bitterness, your coffee should be a burst of
flavour. So, why does it turn bitter? Let’s look into the science of coffee bitterness and see
what causes it.

Technical Factors: Why Does Coffee Taste Bitter?
Overextraction is the primary cause of bitter coffee according to the science of coffee
brewing. The extraction procedure transforms clear water into that deliciously dark brew by
drawing the flavour out of the coffee. Coffee flavorings are dispersed chemically when
water is added to the coffee grounds. The secret is to get the good ones out instead of the
bitter ones, which come out over time.
In light of this, a further major factor that might be to blame for that bitter cup and that you
can easily avoid the next time is dirty equipment.

The leftovers from your most recent brew can quickly add up, and the math isn’t always
pretty. Old coffee residue frequently adds bitterness and makes your most recent brew
taste stale.

How do we fix this?
Clean, clean, clean! Oils will turn rancid if your espresso machine is not regularly cleaned to
remove them.

Coffee flavors that are metallic, bitter, or astringent are frequently blamed on the barista
or the coffee beans. In reality, they are typically caused by dirty equipment.
It’s a common misconception that a machine with low usage doesn’t require as frequent or
careful cleaning as one with high usage. This is simply not true. An inactive espresso
machine will accumulate oil just as quickly as one that is regularly used. Due to the longer
idle times, oil is allowed to build up more quickly because there isn’t any water to pass
through the various components.
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, but it also puts stress on vital parts of the coffee machine (like the
solenoid and the pump). This causes unnecessary and avoidable wear and tear.

Some other issues to consider:

  • Ensure the coffee beans you are using are fresh. 1-2 weeks after roasting is
  • 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; the optimum is
    between 92 – 96 degrees.

If you would like more information regarding any of the above issues, feel free to contact
our Barista “know-it-alls” at or

See our product descriptions on our website for more information on detailed cleaning processes and how to incorporate our Cafelier into your espresso machine cleaning process, or contact

With a Cafelier in hand, you’ll be making the best coffee in no time!