The cork stopper, like the wine, is a natural product and, as such, it is necessary to ensure that it is stored and handled under appropriate conditions so that its quality is safeguarded.
Whenever possible, cork stoppers must be used soon after being received. Long periods of storage should be avoided. The maximum advisable period is up to 6 months, in the appropriate storage conditions.
Stopper packaging should only be opened when stoppers are to be used. Stoppers are generally packaged in bags containing SO2. This gas acts both as an anti-septic and antioxidant, protecting the stoppers.
Unused stoppers should be returned to packaging in bags with SO2 (between 0.5 g and 4 g of SO2 per bag of 1000 stoppers).
Storage of the stoppers should be:
The place where the wine is bottled is essential to the whole process. It should be:
Other precautions to take into account when bottling:
The perfect fit
Making use of the compressibility of cork, the machine compresses the stopper so that it can be inserted into the neck of the bottle. Suitable compression is when the stopper is 2mm smaller than the diameter of the neck at the entrance, and compression greater than 33% of the diameter of the stopper is to be avoided. Thus, a stopper of 24mm in diameter should be compressed to 16.5 mm for insertion into a neck of 18.5mm in diameter.
Compression must never be more than 33% of the diameter of the stopper, as there is a risk that this could compromise its elasticity, with loss of part of the memory and consequent difficulty in the correct sealing of the wine in the bottle. Thus, for a stopper of 24mm in diameter, the recommended compression is about 8mm (which is equivalent to the 16.5mm as mentioned previously).
Making use of its elasticity, the stopper recovers its volume in the first 5 to 10 minutes after being corked, adapting itself to all the irregularities of the neck; and, after just one hour, a uniform force is exercised over the whole surface of the glass. It is therefore not advisable that the bottle be placed in the horizontal position soon after being corked.
In the case of bottling lines where corking comes immediately before the bottles are laid horizontally in the their boxes, the risks can be minimized by prolonging the time that the bottle remains on the production track from the corking machine to the labelling machine. All that is needed is to add more sections of track, making a tight “S” bend so that space is not wasted.
Bottled wine, except in rare cases, is not immune to environmental temperature variations during its transportation and even when it is in the distributors’ warehouse. These temperature variations are responsible for:
Although the variations in diameter of the neck can naturally be compensated by the excellent elastic properties of the cork, the same cannot be said in relation to the variation in volume of the wine and consequent change in internal pressure.
To avoid this problem, the following recommendations should be followed at the time of bottling:
Ensuring that the equipment is in the adequate condition is fundamental to obtain good performance from the stoppers and consequently to prolong the life of a wine. Here are some measures to be taken in relation to the equipment:
Because of the adverse conditions that bottled wine is subject to during the long journeys to be made to arrive at its destination, it is recommended that bottles always be transported in the vertical position.
The use of thermally insulated containers is recommended and the cooler seasons of the year should always be chosen to ship wines, especially for wines which have to be shipped between continents.
If the wine is to be shipped in maritime containers, the last type of cargo used in the container should be informed. If the container is not clean, free of smells and completely dry, it must be rejected. If this is not possible, it should be cleaned with a solution of metabisulfite and then properly dried, for example. Humidity due to condensation during shipping leads to the appearance of fungi which may later lead to the formation of chloroanisoles or other compounds responsible for undesirable odours.
How to store bottled wine
The expression “the cellar makes the wine” is as old as it is true. The temperature, humidity and hygiene of a cellar contribute to the final quality of the wine. The cellar should have the following characteristics:
Technical Cork Stoppers Manual click here.