chicory

Chicory (Cichorium intybus) is not a vegetable with one fixed way of preparation. Under EU geographical indication registration, forms ranging from red and variegated heading types of radicchio called Treviso, Castelfranco, Chioggia, and Verona, to young flower stems called puntarelle, are all positioned as varieties of chicory. Roasted and ground root has also been used as a coffee substitute. From leafy vegetables to processed root products, the range of forms is broad, but what is common to all is the bitterness characteristic of chicory.

The representative compounds that carry this bitterness are lactucin and lactucopicrin, which are classified as sesquiterpene lactones. In one study, lactucin was detected at 42.13 umol/g and lactucopicrin at 11.93 umol/g in raw chicory roots, and neither was present in roasted coffee. However, this concentration is not a fixed value specific to the material. In another study using fresh-cut chicory, the total amount of sesquiterpene lactones was reduced by 60.9–64.5% depending on the washing method, and the composition ratio of lactucin-class compounds was shown to change during storage.

There are also reports that in roasted chicory-containing coffee substitutes, the perception of bitterness changes depending on the order in which they are consumed. In a human taste-comparison test of chicory, coffee substitute, and roasted coffee, the bitterness of chicory was rated lower immediately after roasted coffee consumption, but conversely, the bitterness of roasted coffee did not change even when chicory was consumed first. The authors consider this asymmetry may be because roasted coffee activates a broader set of receptors, whereas the lactones contained in chicory act on a limited set of receptors that desensitize first; however, this is an interpretation from a single test with a panel of 16 individuals.