WHAT STOPPER? FOR WHAT WINE?

Many factors must be considered in a winery to get a satisfactory corking.

The corking is a complex operation from which the later evolution of the wine will depend.

The factors that take part are the wine to be bottled, naturally, but also the glass bottle, the bottling machine and the cork stopper. We are going to concentrate ourselves in the last one because GLM is manufacturer of cork stoppers.

Nowadays the cork stopper quality choice is more and more difficult because as purchase criteria not only the visual aspect and price have to bear in mind but other properties that are not seen but the are even more important (the choice by the manufacturer of the best raw material, the rest of the cork in the courtyard exceeding the time indicated by Systecode, etc., but as this subject is very extensive we will develop it in another article)

Nevertheless there are two basic parameters to be considered for a right choice: the technical conditions of the stopper on each kind and the type of the wine.

The basic properties of the cork are the following:

I. Neutrality, is the capacity of the stopper of not modifying the visual and sensorial characteristics of the wine. It is true that there is not any material totally inert and the cork is not an exception because it is a natural material. The cork stoppers don’t have to give strange taste nor smell to the wine.

II. Durability. The keeping time foreseen for the wine must be in agreement with the longevity of the cork stopper. This period of time is greater in a natural stopper by his special physical and chemical properties and smaller in technical and synthetic stoppers, constituted by food glues and plastic polymers affected by the chemical, photochemical and biological degradation. The chosen cork stopper must assure that the wine in the bottle will not undergo a negative evolution until the maximum foreseen term of the wine conservation.

III. Hermeticness. The contact surface between the glass and the cork must observe this characteristic: the wine does not have to pass between the glass and the cork. This is only gotten bearing in mind the following conditions:

1- A proper diameter of the cork stopper. This condition must be observed at least for the first 45 mm from the highest part of the bottle neck. In the bottles of standard glass of 0,75 cl. that fulfil the UNE 126403 rule about the opening profile for the covering with cork stopper, the stopper diameter is 24 mm.

For greater capacity special bottles with diameters on the opening of the bottle higher than 18,5 mm, the stopper diameter to be used comes from a simple calculation: Stopper diameter = neck internal diameter to 3 mm depth + 6 mm.

2-The minimum necessary time to allow the cork stopper carries out enough pressure on the glass. The maximum elastic recovery of the stopper is gotten at 24 hours after the covering. For instance, the elastic recovery is instantaneous on the plastic stopper but it has not the natural cork stopper capacity to adapt to the glass irregularities. The natural cork stopper is the only one that guarantees a weak microxygenation throughout the time, essential condition for a correct maturing of the wine in bottle.