1- Synthetic stoppers for wine
At the beginning of the nineties, the synthetic stopper appeared as an alternative to the cork stopper.
At first the introduction was difficult , as the winemakers did not know anything about plastic polymers and the chemical engineers did not know the needs of covered wine.
Synthetic wine stoppers have taken more than a decade to be introduced globally and achieve good development based on needs.
Synthetic wine stoppers have been developed mainly in the United States and Australia, countries that have recently increased wine production a lot and have had to provide a solution to the lack of cork .
2- What is a synthetic stopper?
A synthetic stopper is a cylinder of plastic material characterized by a closed cell internal cellular structure that mimics the structure of natural cork.
Synthetic closures have been used in the wine industry for quite some time. This type of stopper has the advantage of keeping the external appearance of the bottle unchanged and the ritual associated with uncorking.
Another great advantage is the total elimination of the cork flavor in the wine.
One of the main properties of this type of stopper is that the wineries can use the same stoppers that are used with cork.
Obviously, one of the advantages is the cost , since it is much lower than natural cork.
3- Characteristics of a stopper
Whether synthetic or natural cork, a stopper must meet the following characteristics:
- Organoleptic neutrality
- Low gas permeability
- Elasticity , so as to ensure a perfect seal between the cap and the neck of the bottle and at the same time a relative ease of extraction.
- Aging resistance
- Low coefficient of thermal expansion .
- Be chemically inert so that it can be used in the food sector.
While natural cork has well-defined physical characteristics and therefore offers universally constant performance, in the case of synthetic wine stoppers the performance depends on the raw materials used, the quality of the internal structure and the production technique used. .
4- Reflections on synthetic stoppers for wine
The permeability of the stopper to oxygen is a fundamental parameter for the conservation of wine.
One of the major criticisms that the synthetic plug has received is related to their low permeability.
This property has proven to be one of the best arguments in favor of the use of synthetic stoppers in oenology.
The greater tightness allows the least use of antioxidants. Likewise, many of the alterations of the wine are imputed to the contact with the air, therefore, for a good conservation of the bottled wine, the capacity of the stopper to maintain a hermetic closure is key , a characteristic that synthetic stoppers more than fulfill.
5- Advantages of the synthetic stopper compared to the natural one
- Its elastic properties are to some degree even better than those of natural cork.
- The permeability to gases is clearly higher than that of cork, which guarantees an extremely effective bottle closure.
- In the case of the synthetic stopper, it is not necessary to keep the bottles lying down to keep the stopper moist, since thermoplastic materials are not subject to dehumidification , with their consequent loss of elasticity, which is the case with natural corks.
- A key aspect to consider is the conservation and storage of bottles covered with synthetic wine stoppers: We find problems related to long-term storage in places where the temperature is high, due to the fact that heat has a detrimental effect on plastic raw materials that make up the plug. It is necessary to take this into account for long shipments in containers exposed to the sun.