Sometimes it is easier to describe what we don’t want rather than what we do when it comes to selecting coffee. For many, the primary desire is to find a coffee that is not acidic or bitter. However, few individuals are aware of what causes acidic or bitter coffee and many confuse the terms.
Acidity is perhaps the most often confused term.This is because when coffee roasters speak of acidity, they’re referring to a desirable attribute in a coffee’s flavor that is an indicator of crop quality.The average coffee drinker, however, tends to equate the term acidity to an acidic feeling or a sour feeling occurring after the coffee is consumed, not an impression on the palate.
Coffee can exhibit a number of naturally occurring acids. Current crop coffee should display ‘good’ acidity and should be a clean, bright flavor resembling lemons.The presence of other acids may indicate issues related to growing or preparation.There is a relationship between the degree of roast and the amount of acid. Generally speaking, acidity declines as roast degree increases.Thus, lighter roasted coffees tend to be more acidic than darker roasted coffees.
Acidity is similar to the carbonation in a soda. We wouldn’t want a flat coffee just as we wouldn’t want a flat soda. Similarly, we wouldn’t want too much brightness in a coffee; rather, we desire something that makes the coffee lively without having an excessive bite.The job and challenge of the roast master is to find the ideal roast that balances acidity with aroma and body.This challenge is furthered as coffee is an organic compound and like all organic compounds, it responds to care, or lack thereof. One of those issues is quinic acidulation.
Quinic acids can be produced during roasting in machines that have poor heat transference. Unroasted coffee beans contain about 12% water by weight.This water must be eliminated before the bean can be effectively roasted. Many poorly designed roasting machines allow the still-wet beans to be exposed to high temperatures for excessive amounts of time. Kaladi utilizes the most efficient heat transference roaster available in the world. In our roaster, water is evaporated off the beans within the first minutes of the roast, thereby sharply reducing quinic acids.
Quinic acidulation can also occur when a pot of coffee sits too long on a heated surface, allowing the brew to “cook.” This is a common experience at countless restaurants when the staff pays poor attention to the coffee and serve a brew that has been allowed to burn for extended periods of time. Airpots and thermal carafes have eliminated quinic acidulation for quality-conscious restaurateurs.
Bitterness is perhaps the easiest element of the coffee experience to describe as it is one of the four primary taste sensations that our tongue perceives.The other three: sweet, salty, and sour, are also experienced in coffee. As with all these characteristics, there are both desirable and undesirable elements to the same taste. A coffee that displays too much of a salty characteristic would be undesirable, while a coffee that has some saltiness is often described as a soft or neutral coffee and can be quite pleasing.Too sour of a coffee causes us to pucker up while the right type of sour sensations can give a coffee a wine-like quality.The right stimulation of the bitter taste buds creates a pleasant bite to the coffee and can be most desirable.
Over roasted coffee can display bitterness due to the excessive breakdown of the coffee’s components, creating an unpleasant, carbon-like flavor.This is especially true if the coffee is a lower grown, low quality bean that has little density. Higher grown, high quality beans are denser and as a result, can be roasted darker.
Excessive bitterness is also a result of improper grinding and brewing of coffee. When there is a lingering bitter characteristic from coffee it is an indicator that the coffee was too finely ground or too much coffee was used in the filter basket because the water used during brewing can’t flow properly.
Finally, the brew rate of a coffee maker has a direct effect on bitterness and acidity. An ideal brewing time is less than four minutes. Most electric home coffee brewers have inadequate water heating elements and result in too long of a brew time. Pour-over coffee makers such as Chemex, Press Pots and Aeropress produce superior flavor since the water contact time is better managed.