- In 2005, an intercomparison of commonly used bottle closures was made by one of Europe's leading providers of laboratory analyses. After six month's of extreme warm storage of wine bottles sealed by different plastic cork products and nature corks, the bottled wines were tested regarding their SO2-stability.
- From the decrease of the amount of sulfuric acid (SO2) in the wines, conclusions on the tightness of the closures can be drawn. The less gas-permeable a cork, the less sulfuric acid is consumed by oxidation. With the test series nature corks, injection-pressed synthetic corks (PRO-KORK), co-extruded plastic corks and injection-casted plastic corks were examined. The plastic corks examined in this investigation, represent the most common production techniques available on the market today.
| Comparison 1: free sulfuric acid | Comparison 2: total sulfuric acid |
|
|
| w/l = warm, horizontal storage, w/s = warm vertical storage. (click for larger image) |
- The diagram shows the large differences regarding the SO2 values after six months. The wines, which were sealed with a PRO-KORK plastic cork, exhibit up to 30% higher residual values of SO2 than the wines, which were closed with a co-extruded plastic cork. With ongoing duration of storage it is to be expected that the oxidation differences between the closures tested, will further increase.
- In the cross section image, the advantages of PRO-KORK over other closures on the market are clearly visible: By the use of injection-pressing technique, in combination with the newly-developed material composition, a higher density of the material is ensured with at the same time high elasticity.
- In contrast to the co-extrusion technique (manufacturing in the continuous string with following cuts on plug length) or the classical injection moulding with up to approx. 48 plugs in one manufacturing cycle, each individual PRO-KORK is manufactured in a separate form-tool. Thus, dimension tolerances are clearly smaller by this production method. From this, the outstanding, always reproducible tightness values result.
- In addition to the tightness requirements, during the product development a special attention was put to the material composition of the PRO-KORK. The composition is completely free from softeners. This was confirmed by investigations of the Fresenius Institute, Germany.
|
PRO-KORK GmbH info@pro-kork.de / phone +49 4221-780192 / fax +49 4221-780194 other products: [aluvin screw closures] [PRO-KORK nature cork] |
|