Glossary of terms used on this site
Caffeine is present at about 1.2% and 2.2% in Arabica and Robusta coffee, respectively. Caffeine belongs to a large class of methylxanthines commonly found in plants and serves as a strong stimulant to the central nervous system. During brewing almost 90% of the caffeine in filter is extracted within the first minute.
Citric acid is the 2nd to 3rd highest organic acid found in coffee after chlorogenic acid. A typical medium roast will lose about 50% of its initial citric acid content and contributes to the bright acidity found in arabica coffee. It is extremely soluble in water and readily extracts into the cup at both ambient and hot temperatures.