Glossary of crown caps for sparkling wines and Champagne
Technical definitions of the main terms used in the production and selection of 29mm crown caps for Méthode Traditionnelle, Champagne and craft beers.
Last updated: 14 May 2025
Production process
Bidule
The bidule is a small food-grade plastic insert positioned inside the 29mm crown cap. Used in the production of Champagne, Méthode Traditionnelle sparkling wines and craft beers, the bidule champagne collects yeast sediment in the bottle neck during secondary fermentation, making disgorgement easier. Mida closures are available with integrated bidule, certified for food contact under MOCA regulations.
Discover Mida caps with integrated bidule →Tirage
Tirage is the bottling operation that initiates secondary fermentation — also called prise de mousse — of Méthode Traditionnelle and Champagne. It consists of adding liqueur de tirage before capping with a 29mm crown cap. Internal bottle pressure reaches between 7 and 10 bars during refermentation, and only a certified quality cap guarantees total tightness throughout ageing.
Secondary fermentation (in-bottle)
In-bottle secondary fermentation is the process that characterises Méthode Traditionnelle, Champagne and craft beer production. After tirage, yeasts consume sugars producing CO2 trapped in the bottle. Duration ranges from a minimum of 18 months to several years for prestige cuvées. The crown cap with bidule must maintain absolute tightness — withstanding internal pressure of between 7 and 10 bars.
Disgorgement
Disgorgement is the operation that concludes secondary fermentation. It involves removing the yeast sediment accumulated in the bottle neck thanks to the bidule integrated in the crown cap. The neck is immersed in a refrigerating solution, the sediment freezes and is expelled when the bottle is opened. The quality of the crown cap used during secondary fermentation is critical to the success of this operation.
Lattes
The term lattes refers to sparkling wine or Champagne bottles in the secondary fermentation phase, positioned horizontally or in pupitres during lees ageing. The bottle is sealed with a 29mm crown cap with bidule, which must withstand the internal pressures generated during the entire ageing period, lasting from a few months to several years.
Product technical
Crimping
Crimping is the mechanical operation by which the 29mm crown closure is crimped onto the bottle bead, creating a hermetic seal. Crimping diameter is a critical technical parameter: Mida Capsules manufactures caps with diameters calibrated between 31.3 and 31.6 mm depending on the material. Stainless steel AISI 304 is the ideal choice for ageing in humid cellars or caves. Our closures are compatible with industrial capping systems such as GAI and similar.
Discover Mida cap technical specifications →Bottle bead
The bottle bead is the glass reinforcement ring on the neck of sparkling wine, Champagne and craft beer bottles. It is the anchoring point of the 29mm crown cap: the closure is crimped around the bead, creating a mechanical seal that must withstand the internal bottle pressure — between 7 and 10 bars — generated by secondary fermentation.
O2TR (Oxygen Transmission Rate)
O2TR — Oxygen Transmission Rate — is the oxygen permeability rate of a bottle closure, measured in cc/package/24h according to ASTM F 1307-20. It is the most important technical parameter for evaluating the quality of a crown cap destined for secondary fermentation: a high O2TR compromises wine organoleptic evolution, causing premature oxidation. Mida crown closures achieve values below 0.001 cc/package/24h.
Discover how Mida tests oxygen permeability →MOCA
MOCA stands for Materials and Objects in Contact with Food — the European regulation (EC Regulation 1935/2004) governing the safety of all materials that come into contact with food and beverages. Mida 29mm crown caps are produced with MOCA-certified materials, guaranteeing absolute neutrality and zero chemical transfer to wine, sparkling wine or beer during ageing.
Liner
The liner is the internal gasket of the crown cap, in direct contact with the liquid or gas in the bottle. In caps destined for secondary fermentation of Méthode Traditionnelle and Champagne, the liner is designed to precisely control oxygen transmission. Mida Capsules offers different liner profiles, bidule-compatible or with integrated liner, certified for food contact under MOCA regulations.
Discover available liner profiles →Certifications and standards
ASTM F 1307-20
The ASTM F 1307-20 standard is the international benchmark for measuring oxygen permeability of bottle closures. It defines the test protocol to calculate O2TR under controlled conditions at 23 ±1°C. Mida crown caps are tested to this standard by ACCREDIA-accredited laboratories, achieving values below 0.001 cc/package/24h.
Discover Mida's certification process →ISO 9001:2015
ISO 9001:2015 is the international certification for quality management systems. Certifying compliance means that every phase of Mida Capsules' production process — from raw material selection to shipment of 29mm crown caps — is controlled, documented and continuously improved to internationally recognised standards.
Discover Mida certifications →FSSC 22000
FSSC 22000 is an international standard for food safety in the production chain, recognised by the Global Food Safety Initiative (GFSI). For a crown cap manufacturer like Mida Capsules, this certification guarantees that production processes are designed to eliminate contamination risks, from raw material management to the production of caps destined for contact with wine and beer.
HACCP
HACCP — Hazard Analysis and Critical Control Points — is the international system for risk analysis and critical control points in food production, mandatory by law in the European Union. Mida Capsules applies HACCP principles at every stage of 29mm crown cap production, identifying and controlling critical points that could compromise the safety of materials in contact with wine and beer.
ACCREDIA
ACCREDIA is the Italian accreditation body, member of the international network ILAC-MRA, which recognises the technical competence of testing laboratories in Italy. Test Reports issued by ACCREDIA-accredited laboratories — such as CSI — IMQ Group used by Mida Capsules — have international legal and scientific validity, guaranteeing full traceability and verifiability of test results.
Types of wines and beverages
Méthode Traditionnelle
Méthode Traditionnelle — also called Méthode Champenoise or Traditional Method — is the sparkling wine production process with in-bottle secondary fermentation. After tirage, the bottle is sealed with a 29mm crown cap with bidule and left to age on lees — from 18 months to several years for prestige cuvées — during which internal pressure reaches between 7 and 10 bars.
Discover Mida caps for Méthode Traditionnelle →Champagne
Champagne is a French sparkling wine produced exclusively in the Champagne region using the Méthode Traditionnelle. AOC regulations govern every production phase, including the choice of closures during secondary fermentation. 29mm crown caps with bidule are the standard closure for this phase: they must withstand internal pressure of between 7 and 10 bars and guarantee an O2TR below 0.001 cc/package/24h.
Sparkling wine
Sparkling wine is an effervescent wine with internal pressure above 3 bars, produced by different methods including Méthode Traditionnelle — with in-bottle secondary fermentation — and the Charmat method. For Méthode Traditionnelle sparkling wines, the 29mm crown cap with bidule is the closure used during secondary fermentation.
Craft beer
Bottle-refermented craft beer is produced with a process similar to sparkling wine secondary fermentation: after primary fermentation, a second in-bottle fermentation produces natural CO2 and develops complex aromas. The 29mm crown closure is the standard for this process, chosen for its mechanical resistance, tightness and organoleptic neutrality guaranteed by MOCA certification.
Further technical questions?
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