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Let me break it to you bluntly. You cannot have wine without sulphites. Widely maligned as a source of headaches and respiratory ailments, the sulphur compounds are, it's true, intentionally added by most producers at various stages of the wine-making process to keep spoilage micro-organisms in check and help shield wine against the ravages of oxygen.

Yet even when not added as preservatives, they're there, albeit in smaller concentrations. That's because sulphites are naturally produced by yeast during fermentation. They're even in that organic merlot you confidently bought because it carried no ominous government warning that it contains trace amounts.

But don't tell that to Donn Berdahl, a winemaker for Orleans Hill in California. For more than a decade, he and partner Tony Norskog have been crafting organic reds that boast an unusual distinction. "Our wines are literally sulphite-free," Berdahl told me on a recent visit to Canada, where he plans to start selling products soon. Liquor boards in Ontario, British Columbia and Quebec have yet to approve them, but he has just begun shipping to private stores in Alberta.

The wines, which include such amusingly named offerings as Our Daily Red and Cote Zero, will retail for about $15. They even come with a bold declaration on the front labels: "No sulfites detected." Berdahl believes they are the only U.S.-made wines to be labelled as such.

It's certainly a clever marketing hook for a brand that has grown from being a niche player sold mainly in organic-oriented California co-op supermarkets to a brand that boasts the highest-selling wholly organic wine in North America, Our Daily Red.

But it's not just marketing spin, Berdahl insists. Unlike virtually all other organic producers, he doesn't merely eschew sulphur dioxide in the winery (a prerequisite for U.S. organic certification), he goes one better. He actually removes the natural sulphites in a two-stage process. Following primary fermentation, he lets the dead yeast deposits – or lees – settle to the bottom of the tank. Most of the sulphites bind to the lees, he says, so when he draws the wine away, he's left with a concentration of between three and five parts per million. Then he induces "malolactic" fermentation using bacteria to convert tart malic acid into soft lactic acid. The bacteria die, the remaining sulphites bind to the sediment and the wine is once again drawn off, he says. "It's at zero parts [per million] every single time."

It sounds intriguing, but I remain skeptical. The techniques Berdahl describes, including malolactic fermentation, are standard for red wines, yet you don't see other organic producers slapping "no sulphites detected" on their labels. Most simply go with the more conservative "no added sulphites."

"Malolactic fermentation will not eliminate the sulphites," says George Soleas, executive vice-president at the Liquor Control Board of Ontario in charge of logistics and quality assurance. Soleas, a PhD scientist who also holds a wine-making diploma from the University of California at Davis, has not tested the Orleans Hill wines but says it is "very, very difficult to produce wines without any sulphites at all." He wonders if it may simply come down to an issue of measurement accuracy.

When I asked for proof of the zero-sulphite claim, Norskog provided me with an independent lab report for Our Daily Red 2012 listing a total sulphite count of "less than 10 ppm," to which the lab added the comment "contains no detectable sulfites." Does that mean zero or does it mean 9 ppm? No way to tell.

I suspect it doesn't matter, at least from a legal standpoint. In the United States and Canada, all wines containing 10 parts per million or more must contain a warning along the lines of "contains sulphites." At amounts below that threshold, there is, in principle, nothing stopping a producer from claiming that sulphites were "not detected" simply because there's no law dictating which of several available measurement techniques is to be used.

Besides, malolactic fermentation aside, the small active sulphite component – known as "free sulphur dioxide" – in most organically made wines tends to bind with oxygen dissolved in the wine pretty quickly, so the levels do indeed become negligible or undetectable by the time bottles hit the shelves, Soleas notes.

I must add that the wines are well-made, particularly Our Daily Red, a blend of cabernet sauvignon, ruby cabernet and syrah, which is smooth, fresh and lightly spicy, showing none of the oxidized, prune-like character that plagues many wines denied sulphur dioxide's prophylactic properties. Will it ward off headaches? I doubt it. If you're bothered by red wine, as much of the population is, the more likely culprits, many experts say, are biogenic amines derived from grape skins.

Those government-mandated warnings are mainly there for another reason, to protect people with severe sulphite sensitivities. This chiefly includes a minority of asthmatics, who may suffer acute respiratory distress and even die if exposed to high concentrations.

But the levels even in non-organic wine are considered low in any case, often falling in the range of 50 and 70 parts per million of total sulphites for red wines, says John Katchmer, an enologist at Enartis Vinquiry, a private wine laboratory in Windsor, Calif. "The commercial yeast strains in use have been selected for a number of reasons, but one of those reasons is that they don't produce a lot of SO2."

As for sulphite headaches, they're "not very common" and "quite overblown," says Dr. Fred Freitag, medical director of the Headache Center at Baylor University Medical Center in Dallas and an amateur winemaker. Many foods, notably dried fruit and cheese, contain higher concentrations of the compounds, he says. "There are more sulphites in a four-ounce serving of eggplant parmesan than in a four-ounce glass of wine, and there's more sulphites in four ounces of ocean whitefish than there is in a glass of white wine," he adds. "No one ever gets eggplant-parmesan headache."

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