Radicchio forcing and blanching is a process that induces new leaf growth in chicory and blanches it through darkness and control of temperature and humidity, among other measures.
Forcing and blanching places already-grown chicory (radicchio), a member of the daisy family, in darkness to make it regrow new leaves and alter their color and texture. One specification explains that the process develops a pleasant bitterness. For several radicchio varieties registered under EU geographical indications, including Castelfranco, late Verona, and late Treviso types in Italy, this process is designated an essential stage.
For the late Treviso type, the prescribed stages of sowing, cultivation, and harvest, followed by preparation before forcing (pre-forcing), forcing and blanching itself, and dividing, washing, and trimming the heads must all take place within the designated production area. A Castelfranco source explains that the process reduces fibrousness and produces a crisp texture and pleasant bitterness. These sources do not provide figures for specific temperatures or durations, however, and the method may vary with the climate and the producer’s skill.
European Commission / 2007 / government document / full text checked
Checked for this overview: Confirmed its designation as an essential process for Castelfranco. / Confirmed the description that the process develops a pleasant bitterness. / Confirmed the description of reduced fibrousness and the development of pleasant bitterness.
The specification describes forcing (forzatura) of the variegated radicchio of Castelfranco as follows: a) the heads are immersed vertically up to the root collar for a maximum of 20 days in spring water at about l1 °C (as written in the original), flowing through large protected concrete tanks; or b) in warehouses, greenhouses, tunnels, or directly in the open field, while keeping an appropriate humidity at the roots, supplying heat to the plants and reducing the light intensity. It also specifies a finishing process: on completion of the blanching and forcing operations, the heads are moved onto layers of sand in an environment at a constant temperature of 18 °C.
Limitations: The existing English source summary does not include the two methods (water immersion / warehouse, greenhouse, or field), the water-temperature, maximum-days, or finishing-temperature figures. These details were confirmed only in the Italian original. The Italian original's edition publication year is unknown, unlike the existing English source, which is from 2007.
The text states that the new leaves lose their fibrous texture and take on a crunchy texture and a pleasantly bitter taste (gradevolmente amarognolo). The same content — that new-leaf formation under shading brings reduced fibrousness, crunch, and a pleasant bitterness — was confirmed in the original Italian text as well.
Limitations: Not a study that verified the chemical mechanism of the process in general; like the existing evidence, this is a description within the disciplinare (production specification).
The Castelfranco version of the specification likewise describes the new leaves as losing their fibrous texture and becoming crunchy, with a pleasant, mildly bitter taste (gradevolmente amarognolo). Its wording is the same as in the Treviso version.
Limitations: Not a study that verified the chemical mechanism of the process in general.
Scope: Production steps specified in the EU single document for Radicchio Rosso di Treviso PGI.
Note: Sowing, postharvest pre-forcing, forcing and blanching, tying, washing, and trimming through to harvest must all occur in the designated area.
The EU single document lists sowing, cultivation, and harvest, as well as pre-forcing, forcing and blanching, tying, washing, and trimming, as processes performed in the designated area.
Limitations: This is not an experimental report giving detailed temperatures or numbers of days for each stage.
The specification states that forcing (forzatura) of Radicchio Rosso di Treviso tardivo uses groundwater (acqua di falda), which in the area is particularly suited to blanching these products. The heads are placed vertically in large protected tanks and immersed up to near the collar for the time needed to reach the right degree of maturity. The tardivo type uses groundwater, with heads immersed vertically.
Limitations: The existing English-language EU PGI source gives only a general process description and does not specify the water source (groundwater). This detail was confirmed only in the Italian original, in a version of unknown publication year that may not fully match the current 2020 revision. This is the wording of the retrieved version. The current amended version checked during verification changes the water-source wording to 「acqua risorgiva（湧水）約11℃」 (in translation: "spring water at approximately 11°C").
Radicchio di Chioggia's standard lacks the process of radicchio forcing and blanchingsupported
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.
Harvest is specified only as cutting the root below the point where the head's basal leaves are inserted, and the only process that follows is toelettatura (trimming with the traditional sickle-shaped roncole knife) in the field or at the collection point. The words forzatura (forcing) and imbianchimento (blanching) do not appear anywhere in the full text of the disciplinare.
Limitations: The "absence of the process" is a negative finding based on the fact that these words could not be found in the body of the disciplinare; it does not exhaustively rule out the practice at actual production sites.