Some people do not like coffee, because they think it tastes bitter. Others feel like that this is exactly how it is supposed to taste. So again, this is quite a controversial question. Let’s try to shed some light into the dark.
Bitter substances are chemical compounds that have one thing in common (attention!): They taste bitter. And we perceive bitterness the same way we do all other flavor categories – sweet, sour, salty, and umami – with the taste buds on our tongue. Contrary to what is often claimed, we identify all basic flavors with our tongue buds. Many plants use bitter substances to protect themselves from hostile predators. For humans, most bitter substances are healthy, as long as they are natural (!). They have for example a positive impact on the digestive system. On the other hand, bitter taste is an alarm signal for our “reptile brain”: Caution this might be toxic. So much for the basics.
It is not surprising, that the coffee used to taste really bitter in former times, when it was roasted in a pan and had to be spiced up with milk and sugar. Today, people tend to describe a coffee as bitter, when it simply has a balanced acidity (provided that it has been prepared well).
The interplay of bitter and sweet components and a fine – well-balanced – acidity is what makes a coffee taste good in the first place. If one component is too dominant, the coffee does not taste round, and might feel like a coating on your tongue. Not good.
Among other things, it produces caffeine and chlorogenic acid. The latter is perceived as bitter (even though it is an acid). Its job is to reduce the stress level of the plant, that is for example caused by solar radiation. It has an antioxidative effect. But back to the initial question.
Even a perfectly roasted coffee can be easily ruined. Just through over-extraction – which simply means: The water has extracted too many bitter substances from the ground coffee. The reasons for that?
• The water is too hot
The ideal brewing temperature is between 198 and 205°F. So, not boiling anymore.
• The grinding degree is too fine – or the grinding degree is not appropriate for the preparation method
The finer the coffee grounds, the larger the surface area and the more substances can be extracted by the water. Which is also a matter of brew time. Quite logical, isn’t it?
Thus, an espresso should be finely ground, because its contact time with water in the portafilter is quite short. A French press coffee on the other hand, is ground coarsely, because it has a rather long contact time with water.
• Too much coffee grounds in proportion to the water
The standard recipe, that should always turn out well, is: 2.1oz coffee grounds for 34fl oz water. Of course, this ratio might vary depending on the coffee type and personal preferences in taste.
But luckily, all of this is no rocket science, it just needs a bit of accuracy. And it is totally worth the effort for a nice, non-bitter coffee.
Here, you find more tips and tricks fort the preparation of coffee.