A naturally occurring cyclic hydroxy acid found in coffee beans, cranberries, cinchona bark, and many other plant materials. In coffee it is esterified with caffeic acid to form chlorogenic acids, the major phenolic compounds behind coffee’s acidity, astringency, and antioxidant capacity; roasting progressively breaks these esters down, releasing quinic acid and shaping cup character. Cranberries owe part of their tartness to it alongside benzoic and malic acids. Analysts measure it as a marker of authenticity and processing in juices and coffee, and its metabolism in the body links dietary intake of plant phenolics to their biological effects.