Let's start at the beginning. What makes a good wine? As the saying goes, "location, location, location." Plant good vines in the right place -- that means, not too hot, not too cold, exposed to plenty of sunshine, in dirt with the correct combination of nutrients, tough enough to make the vine work, not quite tough enough to kill it. A place where in a "normal" vintage, it would take about 100 days on the vine for the grapes to achieve optimum ripeness. A place where it rains a lot in the winter, but not much around harvest time.
Another requisite for making good wine is to not ask any one vine to do too much work -- in other words, don't overcrop, or force vines to produce too much fruit. The normal yield per acre in a high quality vineyard can run from 2 to 5 or so tons. Some vineyards produce less, but they're not too economical -- usually the resulting wine will cost hundreds of dollars per bottle. There are far more vineyards that produce more -- vineyards in the central valley of California routinely push out 10-20 tons per acre. In Australia's Riverina district, they're getting vines to produce 20, even 30 tons per acre. The world's "jug" wines are produced from regions like California's central valley and Australia's Riverina. I pretty much start any basic wine class with this statement: "In wine, quantity and quality work in inverse proportion -- as quantity increases, quality decreases."
Of course, conditions are rarely perfect. If the place is so warm that grapes ripen in a lot less than 100 days, the grapes lack the depth of flavor to make particularly good wine -- they have plenty of sugar, just not enough "physiological" ripeness. If ripening takes a lot longer than 100 days, rain or cold usually messes up the harvest. Winemakers have long had a few tricks to make decent wine in less than perfect conditions. Chaptalization, or adding sugar to the fermenting must is the most commonly known trick. It's legal in France, where in most regions, reaching minimum potential alcohol (in other words, getting optimally ripe grapes) is not always easy, even with global warming. Chaptalizing is not legal in California. Another totally and universally legal option is "green-harvesting" -- pruning just-formed bunches of grapes to thin the crop, forcing the vine to focus its energy on producing fewer, but riper, bunches per vine. Green harvesting can be used in both unusually cool seasons and unusually warm ones.
In Australia winemakers are thumbing their noses at the conventional wisdom. They're pretty much setting out to prove that wine can be manufactured. They've invented machines and processes that seem to be capable of making a veritable silk purse out of a sow's ear. Their innovations are sweeping across the modern wine world. Two such innovations involve the use of reverse osmosis. One use reduces alcohol, the other concentrates juice. Both techniques allow winemakers to ignore two basic rules of viticulture. The first, reducing alcohol, allows growers to pick grapes later, at higher sugar (and potential alcohol), and supposedly at "physiological" maturity. Final alcohol too high? Run it through the reverse osmosis machine and knock off a few %. The second allows growers to overcrop -- allow vines to produce, say, 20 tons per acre instead of 5 tons from the same acre. How? Pump the diluted, underripe must from overcropped vines through a reverse osmosis machine that discards the excess water, concentrating the remaining grape juice. Another Aussie invention, called the spinning cone, is also used for alcohol reduction -- Sutter Home's Fre, a non-alcoholic wine, is made using the spinning cone.
So reverse osmosis is utilized for making potentially thin, diluted wine dark and thick, and for making potentially hot, overripe wine taste smooth and rich. Winery consultants, recognizing that big, rich, smooth, low-acid wines get the biggest scores from wine critics (they're hard to miss in "blind" tastings), are recommending that their clients make use of these machines to guarantee high "scores."
How many wineries in Callifornia use reverse osmosis or spinning cones? Laurie Daniel, wine columnist for San Jose's Mercury News, wrote in her August 17, 2005 column titled "5 Little Wine Secrets," that "Vinovation in Sebastopol, which does reverse osmosis, says it has 1,000 California customers, while ConeTech in Santa Rosa, which has the spinning cone, says it has 650." Daniel estimates these clients produced 16 million cases of wine affected by reverse osmosis or spinning cone processes. That's just California. Don't forget, Australia is the home of mechanical manipulation of wine, and Italian companies are also making reverse osmosis machines.
In other words, chances are, we've all tasted a wine manipulated in this way. Can we tell the difference? The only wine that I've tasted and sold that I'm sure was a product of reverse osmosis is Ridge Vineyards Zinfandel '02, Spring Mountain District. How do I know this? Paul Draper wrote about it on the label. Laurie Daniel interviewed Draper for the article attributed above. Draper said that the grapes for that Zinfandel were all from the York Creek Vineyard, but that his staff, in blind tasting at the winery, could not identify the wine's origin and the decision was made to give it the more general appellation of Spring Mountain District.
Should the use of reverse osmosis in winemaking bother us? After all, other technological advances made since the 1950s -- let's use the invention of temperature-controlled stainless steel fermenters as the starting point -- are widely accepted and embraced. After stainless steel, add neutral pad filtration, bladder/rotating drum presses, sterile super yeast strains, gentler stemmer/crushers...get my drift? When is it too much technology?
With the exception of the yeast, every technique discussed in this blog is mechanical. You can argue that reverse osmosis, like filtration, might remove flavor components from the finished wine, but at least we're not discussing the addition of chemicals, or genetic modification of grape varieties. I'm not at all crazy about the idea of overcropping and concentrating the resulting juice, since it flies in the face of my "quantity/quality" formula, and most of the likely candidates I've tasted that have been subjected to that process still tasted like cheap grape juice. Does that mean I'm sure that I've never liked a wine that was produced by way of juice concentration? I don't know -- I'm not arrogant enough to be certain. In fact, I'm constantly humbled by how much I don't know about wine -- that's why I'm still plugging away at it.
I love the idea of "hand-made," un-manipulated wine. But when I'm tasting wine, the first thing I'm seeking is pleasure -- how a given wine reaches a point where it gives me pleasure is frankly beside the point. Worrying about how a particular wine got to be so good is like worrying about how the chef grilled that steak to perfection. In both cases I'm grateful that the people in charge know what they're doing. If I was sure a given technique always made better wine it would make life more simple, but I'm glad to say it doesn't work that way -- it's just not that simple, which for me makes life in the wine business much more interesting.