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Will UV Treatment of Wine Save Terroir?

It seems like every week, there's a new story about some inventor debuting some newfangled technology to make wine better. Most such stories seem to involve some device that can turn cheap wine into much better wine, auto-magically, which I've now decided is the wine world's equivalent of the famous line "I've got a bridge to sell you."

But occasionally we actually get some news of a technological innovation that doesn't involve auras, electromagnetic fields, or crappy wine, and which might actually make a difference in how wine gets made from here on out.

Such is the case with the story this week, of the first wine to hit the market that has been treated with UV light tanning_bed_barrel.jpginstead of sulfur dioxide and filtering.

Sulfur dioxide is one of the most useful and prevalent chemicals used in the winemaking and winegrowing process. It is used both as a disinfectant for winemaking equipment, but also as an additive to wine, in small quantities, with two primary purposes -- to prohibit the growth of unwanted bacteria and yeasts in the wine, and to retard oxidation as the wine is exposed to air. You've likely heard of that nasty stuff called Brett (Brettanomyces yeast) that gives wine a manure-like smell and flavor? Well it and other bugs like it are some of the chief reasons that nearly every commercial wine in the world uses at least a little sulfur dioxide.

Even after a wine has fermented to dryness (no more sugar for the yeasts to eat) there are still lots of living things in the wine that potentially can cause the wine to change in ways that most winemakers want to prevent. One of the last steps in the winemaking process is to either make sure that there's nothing more for these little critters to feed on, or more commonly, to try to either kill them or remove them from the wine. Hence the use of sulfur dioxide (think edible RAID for renegade yeasts) and filtration (which strips them out of the wine completely with a strainer, so to speak).

The problem with sulfur dioxide is that it stays in the wine, and in large doses can change the flavor and aroma of the wine, as well as increase the likelihood that people with allergies or sensitivities to sulfites will have a reaction to the wine. And the problem with filtration is that it tends to strip out a lot of the character of the wine -- unfiltered wines tend to be more complex and to show their terroir better.

It's the sulfite problem, I believe, that has really motivated the investigation into UV treatment of wines. The idea being that if there is a way to kill the active biological agents in a wine without adding sulfur, then so much the better for everyone. And that's just what this new processing seems to do. Wine gets sloshed around in a series of chambers and exposed to UV light until all the yeasts and bacteria are dead. Simple as that.

Of course, anyone who makes handcrafted wines will tell you that "sloshing wine around in a series of chambers" is not exactly how they'd want to treat their young wine. Much is done in the winemaking process to avoid excessive turbulence and agitation of the wine. You've doubtless read or heard wineries make a big deal about being gravity-fed, and not doing any pumping of their wine, for precisely this reason.

But leaving aside for the moment the question of whether this agitation might do more harm to the wine, this technology interests me the most for its secondary benefit: the potential to keep many wineries from having to filter their wines.

I'll drink wine treated with sulfur dioxide all day long for the rest of my life (well, I do anyway at the moment). But whenever possible, I choose to drink wines (especially red) that are unfined and unfiltered, because invariably they are simply better than wines that aren't.

Filtration and fining (a process used to reduce sediment while the wine is in barrel) are quite common winemaking practices, especially here in the United States. They are used both to prevent biological agents in the wine from acting up and re-fermenting the wine once it has been bottled, and, unfortunately, to remove cloudiness and sediment from wine because American consumers see them as flaws and often refuse to buy cloudy or sedimentary wines or return them after purchase if they notice such things.

It's a sad but understandable state of affairs. A lot of wineries take a better safe than sorry approach, and both fine and filter their wines rather than risk either spoilage or consumer rejection. But as a result, they often strip the soul out of their wines.

But if tomorrow, every winemaker in the world stopped filtering thanks to some handy UV technology, the quality of wine would significantly increase immediately, and, dare I say it, there would be a lot more terroir out there on the market.

Really it's like some sort of Kermit Lynch (an importer who has championed unfiltered wines for years) wet dream. The idea that even $8 wines produced in large quantities could conceivably get to market without fining and filtration is a really tantalizing future. Of course there's still a lot of education to do to convince consumers to ignore the sediment and cloudiness in their wine. But the world would certainly drink better for it.

It's quite encouraging to see technological progress like this in the wine world, especially when it might offer both the opportunity to get more people drinking wine (for less fear of headaches and reactions) and make it easier to make wines with a little more soul.

Comments (12)

AJ wrote:
02.01.09 at 10:01 AM

I can see the line in the sand being drawn. Proponents; deep pocketed wine conglomerates and marketers with hundreds of wines that already taste alike but are adorned with unique and different labels will be tripping over themselves to proclaim their allegiance to the new holy grail of winemaking. " We care about you (the consumer ) and we saw the light (UV) before everyone else. We now give you our new and improved Star Trek wines.

Meanwhile on the other side; the Chihuahuas in our sea of wine, Farmers Almanac winemakers, cow horn burying viticulturist and moon gazing cellarmasters will decry " C'est horrible ". No they will not chant and sip Chai quietly. There's no way they would allow their natural product to be wrung through a vortex of chambers to cleanse it of a natural by-product of the winemaking process. They will claim clumsy scientific manipulations such as these "beat the soul out of fine wine". Only their blend of minimalist winemaking can provide the best expression of terroir.

As science marches on which side will you stand on?

Jared Brandt wrote:
02.01.09 at 10:29 AM

As a maker of wine that rarely filters (sometimes our Rose but that it it and not this year) and as someone who experiments with non-sulfured wines, we use sulfur to prevent oxidation not to control Brett.

If a wine is truly dry and has no nutrients left, most recent research indicates Brett may be present but won't bloom into levels noticeable. Research has further linked the addition of commercial nutrients which aid fermentation as a leading potential cause of Brett blooms. And many wine makers have seen brett blooms after sulfur additions which more research has supported - 30PPM is not effective for 50% of the brett stains to be controlled with a PH of 3.4 http://www.fst.vt.edu/extension/enology/EN/92.html

Oxidation, on the other hand, is much easier to control with sulfur. Many people blame the premature oxidation of white burgundies from the mid 90s on the decreasing use of sulfur.

It will be interesting to see where the UV technology goes. It has been used before in tests by large commercial wineries but the process was never commercialized due to cost - it is expensive to power the lamps and get the exposure necessary.

A side by side taste test would be really interesting - filtered, unfiltered and UVed wine.

Alder wrote:
02.01.09 at 12:12 PM


Thanks for the comments. I hope there's some middle ground there, if this technique truly is effective and doesn't damage the wine with all the churning.

Greg wrote:
02.02.09 at 12:35 AM

A lot of filtering is due to scale - if you are storing wine in million litre containers you better make damn sure it is stable. For small scale winemakers with wine in barrels or containers of only a few thousand litres racking and sulphiting might be enough. Of course it is the large molecules that give wine its complexity and these are the first lost to filtering - you can always tell the extra mouthfeel and complexity of handmade wines.

Hank wrote:
02.02.09 at 5:57 AM

I, too, see this as a technology of scale. The time-tested methods of old (as it were) do indeed work very well for small, artisan producers. Wine is a living thing to them. Why screw it up?
But if I were making lots and lots of wine that I had to get to market quickly (6-9 months for reds), I can see using this to help speed things up.
I don't see that it will reduce filtering though, Alder. Time is needed to settle all of that dead stuff out of the wine (and in large tanks, this doesn't always happen very well or quickly). Plus, people making these sorts of wines are very aware of public perception - and filtering gives you that "sparkle" that most consumers really want.
I see this as a continuation of the industrialization of wine.

Dylan wrote:
02.02.09 at 11:14 AM

I wonder about the impact of new technologies on the perception of wine. I feel as though wine used to, and, for most parts, still carries this quality of romance. This nectar birthed from a intimate relationship with nature. A harmonious act between man and vine bettering each other. This has always made wine stand out as an attractive drink over any other. However, with the increasing use of new technologies, this romance seems to lose its footing as science takes a greater focus. For example, which story better captures your imagination: Chanukah's tale of lamp fuel lasting longer than it should have, or a new type of phillips lightbulb which lasts 10+ years longer than the average lightbulb. I love technology, it will always fascinate me how we constantly innovate and build on our previous knowledge, but you have to admit it can be at the sacrifice of the romantic feeling, like a magician revealing his tricks.

Arthur wrote:
02.02.09 at 4:33 PM

I saw this article on Decanter as well.

My wheels started spinning as I seemed to recall that it is UV light that is responsible for wines becoming "lightstruck".

I would speculate that the amount/duration of UV exposure involved in this process is below that which leads to a wine being "lightstruck".

Does anyone have thoughts on this?

Alder wrote:
02.02.09 at 5:33 PM


Darn. I knew I meant to say one thing more when I wrote the article. YES, very interesting that too much UV light obviously is bad for wine (hence the dark green bottles and dark cellars, eh?). I'm guessing, like you, that the duration is probably quite short, and there may be specific wavelengths that they're using... ?

Thanks for mentioning that.

Travis wrote:
02.02.09 at 5:58 PM

Arthur / Alder,

That's exactly what I was thinking - UV light (of any wavelength) is going to degrade the polyphenolic compounds in the wine, altering the flavor. My guess is that the duration of the process has been optimized to kill viable cells but not noticeably alter the palate.

Arthur wrote:
02.02.09 at 6:07 PM

Ah, Travis
But then we can talk about "noticeably" and to whom?

Guitarguy wrote:
02.06.09 at 10:36 PM


I am not an opponent of cloudy wine or those with sediment. What I am an opponent of is wines that cloudiness or sediment from unfined or unfiltered grape gunk or MOG (matter other than grape) provides food and nutrients to unwanted bacterial contaminants that then spoil the wine. In fact, just last night I had this experience with a wine from Tin Shed, a sour, cloudy beasty thing that was obviously ruined by unwanted microorganisms growing on the unfined trash in the wine. From a technical standpoint, it seems that UV will kill organisms in the treated wine, but they will not give residual protection (as does SO2) to kill anything introduced during the bottling process, resident in the bottle, attached to the cork, stuck to the bottom of filler nozzles, etc. While I applaud the efforts and agree SO2 reduction and less filtering would likely be good things, ensuring stability, especially in wines meant to age, must be paramount.

11.02.14 at 9:47 AM

I savour, cause I found just what I used to be having a look for.

You have ended my 4 day long hunt! God Bless you man. Have a great day.

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