‘ Corked Wines ‘ Fact and Fiction.

Corked WinesCorked Wines

Many wine professional (tasters, writers, consultants, retailers and wholesalers) that sensorily evaluate wines constantly, have been complaining about the increased prevalence of corked wines. Corked-tainted wines have been around since shippers decided to market bottled wine. Most wine professionals agree that cork happens to be the best and most practical of all wine bottle enclosures.

A natural product, cork derived from the bark of the cork oak, it grows only in five countries (Portugal, Spain, France, Italy and Morocco) in the world, and requires Mediterranean climatic conditions to thrive. The bark can be harvested every nine years from a mature tree, and the biggest producer is Portugal. Over the past decade, this country harvested some 225,000 metric tonnes of cork of which 70 per cent were devoted to wine. About 50 per cent of world’s cork comes from Portugal.

Understandably, Portuguese manufacturers are extremely concerned, as is the government over this widely held belief of increasingly frequent corked wine phenomenon.

This widespread belief prompted plastic manufacturers to develop substitutes, most of which have been unsatisfactory to-date, but many large-volume wineries use them due to their low cost. Plastic corks display a number of negative characteristics, and screw caps proved to be insufficiently “ romantic “ for wine enthusiasts.

Millions of dollars were spent to find the culprit and in 1997 it was established, beyond the shadow of a doubt, that 2-4-6 TCA

(Trichloroanisol) and 2-3-4-6 Tetra chloroanisol were the two chemicals responsible.

Accordingly, an International Code of Good Cork Practice (ICGCP) was developed to encounter the problem. This well-thought out procedure outlines how wine corks must be harvested, treated, fabricated and finished. Essentially it prescribes the exclusion of chlorine, which, when combined with phenols in the cork, results in chlorophenols and creation of mould, forming TCA. Minute quantities of TCA taint wine or any other liquids, but it is not harmful.

Some wine importers and distributors accept only ICGCP certified wines and we could safely say that the problem has been solved.

If only things were as simple. First ICGCP procedures are costly and only large producers can afford to follow them. Yet in Portugal there exist some 800 small cork producers unable to follow prescribed procedures due to their high cost. When EU makes compliance mandatory, these small, financially weak, companies will eventually be bought up or fall by the way side. However, since Morocco is not an EU member and could sell to any winery outside the EU. Here wine importers and distributors would have to act in their best interest!

The synthetic cork industry is likely to make inroads in low-end wines because of its cost.

Wine aficionados are unlikely to embrace synthetic corks or screw caps for their favourite alcoholic beverage since they lack the warmth, mystic, natural feel and romanticism of natural cork.

Here are the results of an interesting test conducted by Amorim (a large Portuguese cork manufacturer) and Harpers (and English wine and spirits magazine).

Ninetyone winemakers, journalists, wine trade representatives, and wine marketers were presented five wines for sensory evaluation. Four of the wines had common defects (see side bar) and one was flawless.

Fully 33 per cent of participants failed to identify a single fault; 40 per cent identified one out of four; 21 per cent two out of four; 6 per cent three out of four and only one got all faults. Only two tasters identified the corked wines!

Chloroanisol that causes the wine to smell corked can be airborne, and infinitesimally small amounts can contaminate inordinate amounts of wine. At the beginning of the year, French and American trade publications revealed a well-guarded secret. Some French wine cellars were contaminated with chloroanisol and chlorophenols, the by-products of which have been identified as the culprits of corked wine. Millions of bottles were contaminated but faulty corks were blamed rather than poor cellar practices.

The first symptoms of this “ corked wines “ appeared in 1982 and eventually many more came on stream, until 1993 when a French chemical engineer (Pascal Chattonet) discovered that wooden palettes or cases treated with ploychlorophenols in which bottles were shipped were contaminated. (Polychlorophenols are used as pesticides and fungicides).

Many cellars, especially those with a lot of wooden beams and other equipment were contaminated by chlorophenols and chloroanisols, in turn polluting aging wines.

Discarding all contaminated equipment and wood, including white washing all the walls would have meant extremely high expenses. Some wineries thought it necessary to undertake required remedy, what others have done is a mystery!

It is clear that faulty corks are responsible for some “ corked wines “ but there are other sources for contamination that need to be examined thoroughly.

Common wine faults

Geranium smell; acetic acid (vinegar); 4-ethyl phenol (barnyard, horsey smell); ethyl acetate (nail polish remover); hydrogen sulfite

(rotten eggs); mercaptans (burnt rubber, garlic); labrusca (methyl anthranilate ) ; sour (butyric acid); acetaldehyde (sherry, rotten apple smell); sulphur dioxide ; high amounts of  ethanol (alcohol).


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