Acid Citric or Citric Acid (CA), a prominent type of acid, is widely used and plays a critical role in the metabolism of plants, along with other life forms. In the context of coffee, particularly green coffee, citric acid contributes significantly to the total acidity. This, in turn, plays a key role in shaping the final taste of the coffee, giving it a sharp and distinctive edge.
The concentration of citric acid in coffee beans is subject to change during the roasting process. Its levels peak during the light to medium stages of roasting and subsequently decrease rapidly as the roast level intensifies. It is common to observe that a typical medium roast coffee will lose approximately half of its initial citric acid concentration in the final stages of roasting, and this reduction continues progressively.
Citric acid imparts a strong, tart flavor, which can be likened to that of unripe fruit. It’s important to note that while pure citric acid is frequently utilized as a food ingredient, an excessive amount can be indicative of substandard processing.
In the context of coffee production, unripe or ‘green’ coffee cherries are known to contain substantial levels of citric acid. Therefore, coffee producers, especially those aiming for specialty coffee, are tasked with selecting only the ripest cherries.
Interestingly, as coffee cherries mature, their citric acid content declines while their sugar content increases, thus contributing to the balance of acidity and sweetness in the final cup of coffee. For instance, coffee from Kenya typically presents lower citric acid content compared to Central American coffees. This could suggest differences in plant metabolism between the regions, potentially influenced by factors such as growing conditions and varietal characteristics.
Please note, this is a generalized overview and specifics may vary. For more detailed information, it’s always advisable to refer to scientific literature or academic resources. For instance, studies such as “The Chemical Components of Coffee” by Clarke, R. J., & Vitzthum, O. G. (2001), provide comprehensive insights into the chemistry of coffee.