Research note 048 — 2026-09-04
Italy's Bitter Vegetables — Chicory, Radicchio, Artichoke
North Italian greengrocers stock several kinds of chicory that look nothing alike — a red head, variegated leaves, a slender flower stalk. These are all varieties of the same species, chicory (Cichorium intybus), yet each carries a separate EU geographical indication, and their production specifications (disciplinari) do not describe the strength of bitterness in a single, uniform way. The bearers of that bitterness are sesquiterpene lactones named lactucin and lactucopicrin, whose amounts shift with washing and storage conditions. Artichoke and dandelion, plants of the same family, carry the same skeleton of bitterness too, through sesquiterpene lactones that go by different names. This note lines up cultivars and origin, the specifications' own wording, the compounds and how they behave, and the reach to artichoke and dandelion, within the material collected here.
On this page (9 sections)
- What this page establishes
- Cultivars and origin — one species, different names
- How the specifications write bitterness
- Origins that write the shading process, and those that don't
- The molecule that carries bitterness — sesquiterpene lactones
- Washing and storage move the amount
- Artichoke and dandelion — the same family's bitterness under different names
- What is not known
- Frequently asked
What this page establishes
- Treviso, Castelfranco, Chioggia, and puntarelle are all varieties of chicory, yet it can be confirmed that each is described by a separate EU specification, and each uses different words for the intensity of its bitterness.
- One review states that cynaropicrin is responsible for approximately 80% of artichoke's bitterness.
- One study has measured that washing freshly-cut chicory in warm water lowers the total amount of sesquiterpene lactones by 60.9-64.5%.
- Whether the difference between the specification documents' words "pleasantly bitter" and "lightly bitter" reflects a difference in measured bitterness intensity has not yet been confirmed.
Cultivars and origin — one species, different names
Treviso's red radicchio is defined, under the EU geographical indication, as consisting of the tardivo and precoce types of the chicory variety silvestre.
Scope: Classification under the EU PGI specification
Note: In the legal specification, it is Cichorium intybus L. var. silvestre.
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ingredient-radicchio-treviso —is_a_type_of→ ingredient-chicoryCastelfranco's variegated radicchio is likewise placed within the same genus, species, and variety lineage.
Scope: Classification under the EU PGI specification
Note: A variegated form of Cichorium intybus var. silvestre.
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ingredient-radicchio-castelfranco —is_a_type_of→ ingredient-chicoryChioggia's radicchio is defined as the same variety, comprising two types, early and late,
Scope: Classification under the EU PGI specification
Note: Includes 2 types, early and late.
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ingredient-radicchio-chioggia —is_a_type_of→ ingredient-chicoryand Verona's Rossa cultivar is likewise defined as a chicory product with two types, precoce and tardivo.
Scope: Classification under the EU PGI specification
Note: Rossa di Verona, of the genus Cichorium, species intybus.
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ingredient-radicchio-verona —is_a_type_of→ ingredient-chicoryFurther south, in Puglia, away from Veneto, a geographical indication registration covering the head and young flower shoots (puntarelle) is under way.
Scope: A 2026 EU geographical indication registration application
Note: This is treated as still at the application stage, not as a completed registration.
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ingredient-puntarelle-molfettese —is_a_type_of→ ingredient-chicoryHow the specifications write bitterness
Reading "lightly bitter" and "pleasantly bitter"
Set the specifications' original words side by side, and a word that states a degree of bitterness can be read apart from a word that adds an evaluation. Leggermente corresponds to "lightly," gradevolmente to "pleasantly." There is also an unmodified amarognolo. This table, though, compares how the specifications word things — it is not a table lining up each product's bitterness as actually measured.
| Product / type | Specification's original wording | Near-literal translation | Reader-facing translation | Added degree word | Added evaluation word | Part / type |
|---|---|---|---|---|---|---|
| Treviso tardivo | costola dorsale di sapore gradevolmente amarognolo | midrib of a pleasantly bitterish taste | the midrib is pleasantly bitter | none | gradevolmente | tardivo's midrib |
| Treviso precoce | foglie di sapore leggermente amarognolo | leaves of a lightly bitterish taste | the leaves are lightly bitter | leggermente | none | precoce's leaves |
| Castelfranco | foglie di sapore dal dolce al gradevolmente amarognolo molto delicato | leaves of a very delicate taste running from sweet to pleasantly bitterish | the leaves' taste is very delicate, running from sweetness to a pleasant bitterness | molto delicato is not a degree of bitterness, but the delicacy of the whole taste | gradevolmente | leaves at shipping |
| Chioggia precoce | foglie di sapore dolce o leggermente amarognolo | leaves of a sweet, or lightly bitterish, taste | sweetness or a light bitterness | leggermente | none | precoce's leaves |
| Chioggia tardivo | foglie di sapore amarognolo | leaves of a bitterish taste | the leaves are bitter-tinged | none | none | tardivo's leaves |
Translate both leggermente and gradevolmente as the same "mild bitterness," and the difference between degree and evaluation disappears. Leaving just the one original word in place makes it possible to tell whether the specification stated lightness or pleasantness.
"None" means that no degree or evaluation adverb has been added to amarognolo. It is not a column that denies the meaning of amarognolo itself.
Even where the same amarognolo takes an adverb, the adverbs do not do the same job. Treviso's tardivo writes the taste of the midrib as gradevolmente amarognolo. Gradevolmente adds an evaluation, pleasantness — it is not a word that measures the strength of the bitterness.
Scope: The taste of the midrib under the EU specification
Note: Describes "pleasant somewhat bitter" and "crunchy" as separate attributes.
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ingredient-radicchio-treviso-tardivo —has_sensory_attribute→ sensation-bitterWithin the same Treviso product, though, the precoce type is written as leggermente amarognolo, where leggermente marks a lightness of bitterness. Precoce goes through a binding step (legatura) that suppresses photosynthesis, a process different from tardivo's forzatura-imbianchimento.
Scope: The sensory description of the precoce type in the original Italian-language disciplinare (Art. 6, comma 2, lettera c)
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ingredient-radicchio-treviso-precoce —has_sensory_attribute→ sensation-bitterCastelfranco's specification, too, chooses the same word, pleasant, as Treviso's tardivo.
Scope: The sensory description at shipment under the EU specification
Note: Described not as bitterness alone, but as a continuum with sweetness.
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ingredient-radicchio-castelfranco —has_sensory_attribute→ "A delicate taste running from sweetness to a pleasant bitterness"Chioggia's specification writes its two types, within the same product, in different words. The early type is written with a range,
Scope: The early type under the EU specification
Note: Keeps the range expression "sweet to slightly bitter".
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ingredient-radicchio-chioggia-early —has_sensory_attribute→ "From sweetness to a light bitterness"while the tardivo type is written as amarognolo, with neither adverb, gradevolmente nor leggermente. This means only that no evaluation or degree word has been added in the specification's original wording — it does not mean that the measured bitterness was stronger than in the other type.
Scope: The late type under the EU specification
Note: Recorded as "slightly bitter".
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ingredient-radicchio-chioggia-late —has_sensory_attribute→ sensation-bitterPuglia's puntarelle specification brings in a timeline of its own: it records that the young flower shoots carry a sweet taste with a light bitter aftertaste, and that this aftertaste increases as the plant grows.
Scope: The sensory specification in the EU registration application
Note: Records both a sweet taste and a light bitter aftertaste.
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ingredient-puntarelle-molfettese —has_sensory_attribute→ "A light bitter aftertaste that increases as it grows"Origins that write the shading process, and those that don't
The specifications for Treviso and Castelfranco state explicitly that the process of forming new leaves in the dark (forzatura-imbianchimento) reduces fibrousness and brings a crunchy texture and a pleasant bitterness.
Scope: The traditional process of the Castelfranco PGI
Note: A description of this specification, not a universal effect of the process in general.
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process-radicchio-forcing-blanching —develops→ "Crunch and a pleasant bitterness"Chioggia's specification, by contrast, never once uses the Italian words for this process (forzatura, imbianchimento). Only the harvest method and the hand-trimming that follows it are specified, and the choice not to write down a shading process can itself be read as part of the specification.
Scope: The full text of Art. 5 (Tecniche di produzione e raccolta) of the original Italian-language disciplinare
Note: After harvest (raccolta), only toelettatura (trimming) is specified, and there is no mention of the forzatura-imbianchimento (forced blanching in the dark) process found for the Treviso tardivo, Castelfranco, and Verona tardivo types. This holds for both the precoce and tardivo types.
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ingredient-radicchio-chioggia —lacks_process→ process-radicchio-forcing-blanchingThe molecule that carries bitterness — sesquiterpene lactones
Behind the bitterness that each disciplinare writes about in words sits a compound with a name of its own. Lactucin is present in large amounts in raw chicory root, keeps much of that amount in roasted coffee-substitute powder, but drops sharply in concentration once it becomes an extract.
Scope: Chicory and chicory-based coffee substitute in the cited research
Note: Concentration varies with the material and preparation.
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ingredient-chicory —contains→ compound-lactucinLactucopicrin is present in the same root, and likewise drops in concentration in the extract. Neither compound is present in roasted coffee itself.
Scope: Chicory and chicory-based coffee substitute in the cited research
Note: Concentration varies with the material and preparation.
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ingredient-chicory —contains→ compound-lactucopicrinLactucin is reported as a compound that contributes to chicory's bitterness.
Scope: Chicory and chicory-based coffee substitute in the cited research
Note: Receptor activation together with the concentration in the food forms perception.
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compound-lactucin —contributes_to→ sensation-bitterLactucopicrin is likewise reported as a compound that contributes to bitterness, and is placed as the most potent of the chicory-derived lactones tested.
Scope: Chicory and chicory-based coffee substitute in the cited research
Note: Receptor activation together with the concentration in the food forms perception.
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compound-lactucopicrin —contributes_to→ sensation-bitterWashing and storage move the amount
A study comparing four washing conditions for freshly-cut witloof chicory reports that sesquiterpene lactone content and bitterness fell significantly under every washing method, and that warm-water washing reduced the total amount by 60.9-64.5%.
Scope: 4 washing conditions for freshly-cut witloof chicory
Note: Warm-water treatment reduced total sesquiterpene lactones by 60.9-64.5%.
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process-chicory-washing —reduces→ sensation-bitterA separate storage trial compared the dark held at 8 degrees against 4500 lux of light for 11 days, and reports that the sesquiterpene lactone concentration in the central axis rose clearly in the lit group. The rise in the leaves was smaller than in the central axis.
Scope: A storage-condition comparison trial on 2 cultivars of witloof chicory
Note: This study consists only of chemical analysis (HPLC-DAD-MSn) and measurements of pigments and O2/CO2; it did not carry out a sensory evaluation of bitterness. The paper's opening states that "greening is generally associated, as a major quality defect, with increased bitterness," but this is background description, not a result of this study itself measuring the perception of bitterness.
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ingredient-witloof-chicory —has_composition→ "Under light exposure during storage (at 8°C, dark vs. 4500 lux illumination, for 11 days, packed in consumer polyamide bags), the sesquiterpene lactone concentration in the central-axis tissue of 2 cultivars rose clearly in the illuminated group. The rise in leaf tissue was smaller than in the central axis. Photosynthetic pigments (chlorophyll derivatives and beta-carotene) also rose clearly in the leaves under illumination, and respiration was likewise elevated in the illuminated group."A study of the roots of 3 chicory cultivars grown in northern France developed an ELISA to quantify the bitter component 11beta,13-dihydrolactucin, and reports that its concentration ranged from 485 to 1720 milligrams per 1 kilogram of dry matter, correlating with the strength of bitterness at r=0.9.
Scope: The roots of 3 chicory (Cichorium intybus) cultivars grown in northern France
Note: A follow-up investigation into an item that had been deferred (11beta,13-dihydrolactucin). The existing claim had only compositional information -- content that rose or fell in the root -- with no connection to bitterness. This one is based on primary material that directly links the compound to bitterness: a correlation between the ELISA-quantified value and the sensory panel's bitterness assessment (r>0.9). Because the body text has not been read in full, this is kept as supported rather than established.
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compound-11-13-dihydrolactucin —is_correlated_with→ sensation-bitterArtichoke and dandelion — the same family's bitterness under different names
Artichoke, a different genus but the same family, Asteraceae, as chicory, also has a sesquiterpene lactone with a name of its own. A review sets out that the bracts contain several sesquiterpene lactones, mainly cynaropicrin, and that the stem, too, carries a small amount of cynaropicrin.
Scope: Artichoke's bracts and stem
Note: Content differs by plant part, so no single concentration figure is given.
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ingredient-artichoke-globe —contains→ compound-cynaropicrinCynaropicrin is recorded, in a review, as the component responsible for artichoke's characteristic bitterness.
Scope: Artichoke's characteristic bitterness
Note: A review's synthesis of primary research.
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compound-cynaropicrin —contributes_to→ sensation-bitterAnother review goes further, stating that cynaropicrin is responsible for approximately 80% of artichoke's characteristic bitterness.
Scope: A literature review on the bitterness of artichoke (genus Cynara) plants.
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ingredient-artichoke-leaf —has_major_bitter_compound→ compound-cynaropicrinThe PDO specification for Sardegna's spiny artichoke (Carciofo Spinoso di Sardegna) defines this product's flavor as a balance of bitterness and sweetness brought about by polyphenol derivatives and cynarin.
Scope: The EU PDO sensory specification
Note: The causal link to the compounds is recorded as the specification document's own explanation.
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ingredient-artichoke-sardegna —has_sensory_attribute→ "A balance of bitterness and sweetness attributed to polyphenol derivatives and cynarin"Moving to a still more distant genus, a review states that in dandelion, another member of the family Asteraceae, bitterness is likewise given mainly by sesquiterpenoids.
Scope: A review of bitterness in the dandelion genus
Note: Does not assert the contribution rate of any individual compound.
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ingredient-dandelion-leaf —has_bitterness_attributed_to→ "Sesquiterpenoids"What is reported as the leaf's major sesquiterpene lactone is taraxinic acid beta-D-glucopyranosyl ester. Chicory's lactucin and lactucopicrin, artichoke's cynaropicrin, dandelion's taraxinic acid glucoside — the bitter vegetables of the family Asteraceae each carry the same skeleton of bitterness in a compound with a different name.
Scope: The leaves of Taraxacum officinale
Note: A summary of HPLC/MS and isolation studies cited by the review.
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compound-taraxinic-acid-glucoside —is_major_sesquiterpene_lactone_in→ ingredient-dandelion-leafWhat is not known
Whether the difference between the disciplinari's words — pleasant, light, and unmodified — reflects a difference in actually measured bitterness intensity cannot be answered within the range of material confirmed here. These are not values measured by a trained sensory panel, but descriptors chosen by the specification documents, and the possibility that this is merely a difference arising from how each document was drafted has been noted below, in each case, as a limitation. Likewise, no material has been found here that directly connects the measured fact that compound amounts shift with washing and storage to the disciplinari's own choice of words.
Frequently asked
Why is chicory bitter?
Raw chicory root has been measured as containing around 42.13 umol/g of lactucin and around 11.93 umol/g of lactucopicrin, with a certain amount remaining even in roasted coffee-substitute powder. Lactucopicrin is reported to exceed lactucin in the strength of its action at the receptor, and it has also been pointed out that ranking bitterness strength by concentration alone is misleading. In an ELISA analysis of a cultivar grown in northern France, the correlation between dihydrolactucin concentration and bitterness strength is reported as r=0.9.
Does radicchio's bitterness differ by cultivar?
Radicchio's specifications choose different words for each product, even for the same "bitter." Treviso's tardivo records the taste of the midrib with an added evaluation, pleasantness. It is Chioggia's late type that is recorded, with no modifier at all, as simply bitter, while Chioggia's early type, by contrast, is written with a range, sweetness or a light bitterness. Puglia's puntarelle brings in a separate axis, time, recording that the young flower shoots' bitter aftertaste grows as the plant grows. What is being compared here is the wording of the specification documents, not figures for bitterness intensity measured by a trained sensory panel. How bitter each cultivar is cannot be ranked from the wording difference alone.
Related:chicory /Radicchio Rosso di Treviso tardivo /Radicchio Variegato di Castelfranco /globe artichoke /Carciofo Spinoso di Sardegna /dandelion leaf /lactucin /cynaropicrin
Related research notes: A World Map of Debittering / How Bitterness Gets Institutionalized
Source ledger: the source ledger
How to cite this page
Aoki, M. (NIGAMI LAB) (2026). Italy's Bitter Vegetables. https://nigamilab.com/en/notes/italian-bitter-greens/
Each claim card has a stable anchor (#clm-…). The dataset is CC BY 4.0; see the data page. Dataset DOI: 10.5281/zenodo.22739101