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Written by NewScientist   

Make Cheap Wine Taste Like a Fine Vintage?


NewScientist (17 Dec 2008) —  Most people have got one lying around somewhere: a bottle of cheap, discount nasty wine left over from a dinner party just waiting to be offloaded on someone else - or quaffed late one night when the good stuff has run out.  But what if you could turn that bargain-basement plonk into fine wine in minutes?  In these straitened times it could be just the thing a wine lover needs.

Traditionalists, of course, would insist that nothing can replace genuine quality plus long, slow ageing in an oak barrel and years of storage in cool, cobwebby cellars.  But could there be a short cut?

Over the years, inventors have come up with dozens of widgets that they claim can transform the undrinkable or bring the finest wines to perfection without the long wait. Sadly, there's little scientific evidence that most of them work.  Looks like you're stuck with the plonk.

Or are you?  Fortunately, there is one technique that stands out from the rest.  It is backed by a decade of research, the results have been published in a peer-reviewed journal and the end product has passed the ultimate test- blind tasting by a panel of wine experts. No fewer than five wineries have now invested in the technology.

The secret this time is an electric field.  Pass an undrinkable, raw red wine between a set of high-voltage electrodes and it becomes pleasantly quaffable.  "Using an electric field to accelerate ageing is a feasible way to shorten maturation times and improve the quality of young wine," says Hervé Alexandre, professor of oenology at the University of Burgundy, close to some of France's finest vineyards.

No matter how impatient or undiscriminating you may be, fresh wine is undrinkable and can have horrible after-effects.  Expect an upset stomach, a raging thirst and the world's nastiest hangover.  The youngest a wine can be drunk is six months.  Most, especially reds, take longer to achieve the required balance and complexity.  The finest can take 20 years to reach their peak.

During ageing, wine becomes less acid as the ethanol reacts with organic acids to produce a plethora of the fragrant compounds known as esters.  Unpleasant components precipitate out and the wine becomes clearer and more stable.  Red wines mellow as bitter, mouth-puckering tannin molecules combine with each other and with pigment molecules to form larger polymers, at the same time releasing their grip on volatile molecules that contribute to the wine's aroma.

These reactions take time and need a small but steady supply of oxygen.  In barrel-aged wines, oxygen leaks through the wood, while wine matured in steel tanks is often helped along by introducing microscopic oxygen bubbles.

There are good commercial reasons why winemakers would love get their hands on a speedier alternative, especially in places like China where the industry is young and booming.  It would allow them to get their wines into the shops faster to meet ever-increasing demand, and cut the cost of storage.

The food industry has experimented with electric fields as an alternative to heat-treating since the 1980s, and 10 years ago Xin An Zeng, a chemist at the South China University of Technology in Guangzhou, decided to see what he could do for wine.  Early results were promising enough for Zeng and his colleagues to develop a prototype plant in which they could treat wine with fields of different strengths for different periods of time.

They pumped the wine through a pipe that ran between two titanium electrodes, fed with a mains-frequency alternating supply boosted to a higher voltage.  For the test wine, the team selected a 3-month-old cabernet sauvignon from the Suntime Winery, China's largest producer.  Batches of wine spent 1, 3 or 8 minutes in various electric fields (see diagram).  The team then analysed the treated wine for chemical changes that might alter its "mouth feel" and quality, and passed it to a panel of 12 experienced wine tasters who assessed it in a blind tasting (Innovative Food Science and Emerging Technologies, vol 9, p 463).

The results were striking.  With the gentlest treatment, the harsh, astringent wine grew softer.  Longer exposure saw some of the hallmarks of ageing emerge- a more mature "nose", better balance and greater complexity.  The improvements reached their peak after 3minutes at 600 volts per centimetre: this left the wine well balanced and harmonious, with a nose of an aged wine and, importantly, still recognisably a cabernet sauvignon.

Analysis revealed some significant chemical changes.  Most obviously, there was a marked increase in reactions between alcohols and acids to produce esters.  This led to a reduction in concentrations of the long-chain alcohols known to be responsible for nasty odours and a burning mouth feel, while the increase in the concentration of esters boosted the aroma and the perception of fruitiness.

Two other good things happened: the breakdown of proteins produced free amino acids that contribute to taste and there was a noticeable reduction in the levels of aldehydes, which are responsible for "off" flavours.  You can have too much of a good thing, though.  Upping the voltage and applying it for longer brought new and unwanted changes, including the generation of new undesirable aldehydes.  Zap it too much and the result, the panel found, was worse than the untreated original.

Although Zeng cannot yet explain how exposure to an electric field alters the wine's chemistry, his results show that under the right conditions the technique can accelerate some aspects of the ageing process.  "Not only can it shorten a wine's normal storage time, it can also improve some lower-quality wine," he says.  "It works just as well with other grape varieties such as merlot and shiraz."  Five Chinese wineries have begun trials.

Sadly for wine drinkers feeling the pinch, there's no immediate prospect that you can try this for yourself.  "I have thought of designing a set of equipment for use at home," admits Zheng "...but not yet."

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