Tasting Coffee – Part Two: Developing Bitterness

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In part one on tasting, we outlined the basic differences between taste and flavour. Concluding, the experience of tasting is deceptively complex. For part two, I want to talk more specifically about how this relates coffee.

Let’s start with the classic dark roast. It is famous for being bold, bitter, and smooth. These traits are due to a number of chemical reactions including an increase in quinic acid, degradation of chlorogenic acids, and caramelization of sugars. The roasting process overwrites the flavour traits associated with origin and you get a cup with very little perceived acidity. Add enough sugar and your cup with be balanced between bitter and sweet, which can be very pleasant. Especially when accompanied with more sugar in the form of a sweet pastry that provides contrast with every bite.

Modern coffee re-orientates the taste profile away from the flavours of the roast process towards those associated with the green coffee itself. In place of the universal notes of bitterness and char, we showcase the floral, cirrus, berry, and fruit tastes unique to a crop. Not all farms are created equal, so the basis of well-executed modern coffee is reliant on the producer. At its best, the cup balances sweetness with bright and clean acidity.

However, modern coffee frequently fails to create balance for two main reasons. First, underdevelopment of the inner coffee bean. While the outside of a coffee bean may appear to have a perfect shade, the inner bean lagged behind. It will taste “green” with the flavours of pea pod, celery, grass, hay, or under-ripe fruit. Second, there is a roaster myth that a faster roast time means better clarity and quality of acidity. Many roasters charge (or pre-heat) to high temperatures to accelerate the roast process. The result is charring or tipping, as the outer beans burn against the drum. The end result is a blunted cup with those char notes of a dark roast. These speedy roasts also often mean that gradient between inner bean and outer bean is offset resulting in a rough burnt on the outside/raw on the inside or over/under flavour profile.

The interesting element of taste that comes across in both of these scenarios is …. bitterness! The line between the pulp of an orange and its peel is one between sour and bitter. Equally, even if the roast communicates some level of sour and sweet but has been charred, there is a dark roast element clouding the cup. Meaning despite appearance that these are on other end of the spectrum, they actually share more of the flavours associated with a dark roast than a well-developed or ‘in-between’ coffee.

Let me just close with a tidbit on flavour and taste that draws this all together. Commonly, bitter and sweet are considered complimentary. Sour and sweet also fall into the category of complimentary. Sour and bitter, however, clash with each other! DUN DUN DUN! The result of poor roasting in our industry means we are pushing cups with conflicting, angular, and unbalance notes. No wonder people are seeking ‘smooth’ coffees. The solution is well-developed coffees because it means balance between elements and, most importantly, sweetness.