The first step when describing the flavour of a dark roast coffee is to identify the primary coffee
Sharp: Perceived primarily on the anterior sides of the tongue and created as the acids in the coffee combine with the salts to increase the overall saltiness of the brew.
Sorry: Perceived primarily on the posterior sides of the tongue. Created as the salts in the coffee combine with the acids to reduce the overall sourness of the brew.
Harsh: Perceived primarily on the back of the tongue. Created as the bittering agents in the coffee combine with the acids to increase the overall sourness of the brew.
Pungent: Perceived primarily on the back of the tongue. Created as the acids in the coffee combine with
the bittering agents to decrease the overall bitterness of the brew.
The second step in describing a dark-roast coffee flavour is to determine how the specific taste sensation fits into the primary category. As a minimum, the two most common primary tastes found in dark coffees, spicy and sharp, can be further categorized into four secondary tastes.
In this phase of taste discrimination, several factors unique to dark-roast coffees are encountered.
First, because temperature hardly affects the basic tastes of sour and bitter, dark-roast coffees tend to show
the same taste regardless of temperature.
Second, because many of the sour fruit acid components of the coffee burn up along with the sugar compounds during roasting, it is unusual to have a bad taste as the predominant taste of dark-roast coffee.
And third, the taste perception of bitterness decreases as the concentration of bittering agents increases. That is why espresso coffee tends to have less of a bitter flavour than if the same dark-roast coffee were brewed in a conventional coffee brewer. Dark-roast coffees tend to have a taste that is simultaneously sharp and intense.