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Bacchus to the future: High-tech winemaking


IT IS five o’clock in the morning at the height of California’s harvest season, and the full moon hanging low over the Carneros hills bathes the chardonnay vineyards in cheese-yellow light. A crew of 30 Mexican grape-pickers, wearing headlamps and orange safety vests, races down the rows in silence, deftly severing the bunches with crescent-shaped knives and dropping them into plastic bins. They have to work fast in the cool night air, taking a few seconds to strip each plant, because within an hour it will be too warm to harvest the fragile grapes.

“They are skilled, more than they’re given credit for,” says Towle Merritt, a general manager at Walsh Vineyards Management, the viticulture firm that employs them.

Harvest night has also arrived at a cabernet sauvignon vineyard 36km (23 miles) to the north, in the heart of the Napa valley. But here there are no artificial lights, portable toilets or on-site sorting teams. Instead, a single driver pilots a 3.65-metre (12 feet) high arch-shaped tractor towards the end of a row. The earth below is highly uneven, but the vehicle’s massive wheels, each with its own gyroscope and hydraulic controls, extend, twist and tilt to keep the cab perfectly level as they line up on either side of the vines. The driver launches the tractor straight along the top of the row. The engine whirrs, branches crackle and leaves fly into the air as he zips along.

Underneath, ten pairs of flexible fibreglass rods are swinging back and forth, their amplitude, frequency and spacing specified by the driver. The vibration separates the grapes from the plant, and a conveyor belt brings them to the top of the vehicle. There, they pass over a series of rollers whose spacing lets the berries through while trapping stray stems and leaves. The vines look undisturbed save for their lack of fruit, their naked stems eerily exposed. The machine, made by Pellenc, a French firm, will harvest 20 tonnes of grapes tonight: enough to make 18,000 bottles of wine, and a harvest that would otherwise require 40 workers.

Mechanical harvesting is not new: makers of bulk wine dispensed with hand-picking in the 1970s. But using machines was long associated with low-end wineries that could not afford traditional artisanal methods. “Technology has vastly improved the low end,” says Tim Keller, a former winemaker at Steltzner Vineyards in Napa. “There’s no longer an excuse for making a defective wine.”

As consumers remain seduced by the notion that wine should be made by humble farmers with as little intervention as possible, fine-wine labels still try to keep their experiments with technology under wraps. But they are quietly deploying technology in a new way: not just to make bad wine decent, or to make good wine more cheaply, but to make already-great wines greater still.

A picky bunch

Few industries are more suspicious of change than winemaking. Archaeological evidence suggests that humans have been drinking fermented grape juice since at least 7000BC. Presses and fermentation vats were in use by 4000BC. Even the sites of the best vineyards have been known for centuries: in 1663 the English diarist Samuel Pepys wrote of “a sort of French wine, called Ho Bryan, that hath a good and most particular taste.” The 2010 vintage of Haut Brion starts at $800 a bottle.

Most of this accumulated know-how involves creating the best conditions for winemaking to take its natural course. The beverage occurs in the wild: if grapes are left to rot, their juice can ferment using native yeast. But there are an infinite number of pitfalls along the path from vine to wine: weather, pests, problems with fermentation, oxidation and so on.

Through centuries of trial and error, vintners have discovered techniques to minimise these risks. Of recent advances in this field, the most technically impressive is probably optical sorting. Food companies have long used cameras and image-processing software to separate and discard low-quality products. But the first sorter designed especially for wine was not released until 2007.

Made by Pellenc, it looks like an oversize pinball machine. After destemming, the grapes fall onto a vibrating metal plate that separates them, and proceed to a conveyor belt made of 99 thin rubber cords moving at 22kph. They then pass under a brilliant halogen light, where a digital camera takes a snapshot. In 30 milliseconds, the device compares each berry’s shape, size, and colour with the winemaker’s guidelines, and “shoots down” the rejects with a quick puff of air, making a sound like a typewriter.

“It looks like a blueberry tart,” says Bruno-Eugene Borie, the owner of the Ducru-Beaucaillou winery in Bordeaux, while admiring his machine’s output. “All the berries are perfect.”

Pellenc has already sold more than 1,000 of the units, which can cost up to $250,000. Its success has attracted competitors, such as Bucher Vaslin, another French firm. France is the undisputed global leader in wine technology.

As Mr Merritt notes, the country has a greater demand for mechanisation than America because its agricultural wages are higher. And France’s reputation means that its elite winemakers, unlike those in other countries, do not have to worry about criticism from elite French winemakers.

Seeking closure

One of the few areas where a non-French company has taken the lead is in closures—a logical consequence of the requirement under French law that wine must be bottled using natural cork.

The traditional seal has long frustrated producers with the inconsistent amount of air it lets through and its tendency to become tainted with TCA, a compound that makes wine smell like wet cardboard. However, the primary alternative—a fully airtight screw cap—is shunned by oenologists who believe that ageworthy wines require a bit of oxygen to mature.

After leaving Steltzner, Mr Keller co-founded a startup, VinPerfect, that he says should end the “closure wars” once and for all. It makes a screw cap containing an aluminium-coated plastic liner, similar to the finishes on mirrored sunglasses. This allows the winemaker to choose precisely how much oxygen should enter the bottle over time, while eliminating the risk of TCA.

Preventing premox

Another longtime headache for vintners is premature oxidation (“premox”), a condition that makes white wines taste like a browned apple or toasted bread. Vivelys, a French firm, has found that adding controlled amounts of oxygen before fermentation makes wine more resistant to premox later on, as well as giving it a creamier mouthfeel.

Its new Cilyo machine injects small quantities of the gas into a sample, determines how fast the “must” consumes it and calculates the optimal amount. At Domaine Chandon in Napa, owned by the French luxury conglomerate LVMH, the device is used to determine a separate dosage for each tank.

Reverse osmosis

A more controversial wine-adjusting technology is reverse osmosis (RO). In the 1990s, partly driven by the preferences of Robert Parker, an influential American critic, many producers began delaying their harvests in order to make fuller, fruitier reds that could be drunk without lengthy cellaring. More ripening time meant more sugar, which fermentation turned into alcohol. Wines that once carried 12-13% alcohol began reaching 15-16% or more.

To avoid this side-effect, producers turned to RO, a technique that is also used to desalinate water. The smallest molecules in wine are water and alcohol. By passing wine at high pressure over a membrane with tiny pores, those compounds can be separated from the rest of the liquid. Only the water is added back in, reducing the wine’s alcohol level. Slightly more porous membranes can also be used to remove other unpleasant chemicals like acetic acid (vinegar) and ethyl acetate (a chemical used as nail-polish remover).

“Some winemakers try the same wine at a host of different alcohol levels to see which tastes best.”

RO has its share of critics. Purists contend that it is “cheating” and takes wine too far away from its natural roots; sceptics argue that the process strips crucial aromas as well as alcohol. But demand for the practice far exceeds the number of producers that will admit to it.

WineSecrets, a firm in California, even lets clients try the same wine at a host of different alcohol levels to see which one tastes best. “Winemakers can’t be honest about what they do, because they’ll be accused of manipulation,” says Clark Smith, an American consultant credited with popularising RO.

“When winemakers hear ‘manipulation’, they think, ‘What, you don’t want me to pick the fruit or crush the grapes?’ They’re forced to dissemble or they get demonised.”

The need for technology does not end once the bottles leave the winery…..

The Economist: Read the full article

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