BudBurst

Many people would be able to identify a bottle of wine that was truly faulty and, in a restaurant, ask for a replacement. But would you be able to tell what the fault was or what to blame for it? It is all to do with perception threshold. Different faults require different parts per thousand or even million to be perceived.

Some people are more sensitive to certain faults than others so while the host, who may taste the wine as it is brought to the table, is happily quaffing, one or more guests could be secretively retching into their napkins. Depending on how well you know your host and judging, diplomatically, how much of an ego dent your comments could produce, it might be worth discreetly asking people to have another careful sniff.

 At a wine faults workshop this week, it was made clear that a fault is only a fault if the people drinking the wine consider it to be. For example the "fault" brett - produced from brettanomyces yeast acting on the phenolic acids of the grape - is a characteristic that some tasters love and some winemakers deliberately introduce. It can produce strong animal characteristics that enhance a wine's complexity and increases some people's pleasure.

Of course it is very important to get the balance right because the smallest increase tips a wine over from animal (yum) to bretty (yuck).  And even in the lower doses some people adore the fragrant pong while others will recoil in horror at the filthy stench. Perception is all.

Then there is actual corkiness. Produced by TCA, TBA and TeCA it has various origins like the high levels of chlorine used to clean the winery and equipment, the breakdown of other cleaning agents by funghi in the winery - low ventilation and high humidity contibuting to high levels in the atmosphere.

The cork industry is keen to point out that it is not something inherently present in the corks more of a contamination at the winery. The plastic in alternative closure linings etc are equally susceptible to this contamination. With increased awareness, far higher standards of hygiene than ever before and alternative cleaning solutions available the problem should be getting better. However despite some high profile cases in California back in 2004, there are still many wineries taking the easy option and continuing bad practices.

At the other end is a sulfide problem that produces a tomato, truffle, cabbage, rubber character. This is reduction, the opposite of oxidation and the result of a complete seal which prevents any movement of oxygen into the wine. Unlike oxidation though, this can be corrected sometimes as simply as swirling the wine in the glass or decanting the bottle thereby allowing some air contact and dissipating the bad aromas.

This problem has been most associated with screwcaps which provide such an affective seal that all the positive benefits of cork permeability have been lost alongside the problems that can occur for freshness through excessive permeability.

New Zealand wineries have famously chosen to address this by slightly oxidising the wine before bottling in order to achieve balance once the wine is in bottle. As is often the case with the New World, they are quick to respond to problems and criticism.

However this is a dangerous and nervy solution and not always successful. Pascal Chatonnet, leading faults scientist, oenologist and consultant to wineries all over the world, argues that some of the essential character and originality is lost through this process and the overall quality and elegance is compromised, though this is not necessarily understood by the consumer as the original wine is not available to compare.

What is important to the cork industry is that while a consumer might recognise the wine is faulty, the only real language employed to describe or attribute the fault invokes cork. This is of major concern and is where the charm offensive needs to conentrate, for cork may not have played any part whatsoever.

For consumers the challenge to the industry as a whole is to find a closure with the correct level of permeability and which is kept free of contamination. It is in everybody's interests and with a more frank discussion opening up we can only hope that solutions won't be too far away.