(Wines&Vines) - —Siduri Wines began testing the 2012 vintage of its multiple Pinot Noir wines to verify that levels of gluten post-bottling remain “undetectable,” according to winemaker Adam Lee.

Lee already has bottled some 8,000 cases of three different 2012 Pinot Noirs, with another 8,000 cases of vineyard-designates yet to come. The Santa Rosa winery, which sells 60% of its production direct to consumer, charges an average of $36 per bottle.

Lee said a gluten-intolerant staff member inspired him to check the gluten levels in his wines. Most modern wines contain negligible levels of gluten, which might remain in trace levels after fining or from the wheat-flour paste traditionally used to seal some oak barrels.

The latter possible method of contamination prompted Lee to test his wines when were are out of the barrel and into the bottle, a process he outsources to ETS Laboratories, at a cost of “several thousand dollars,” he said.

Lee asked barrel suppliers about possible gluten contamination and, he said, “They just didn’t know. I’m a skeptic. When someone is trying to sell you something and claims never to have had a problem, I like to see for myself.”

While investigating, he learned that the wheat-flour paste seals are also prohibited in the production of kosher wines. Jeff Morgan, co-owner/winemaker at Napa’s Covenant Wines, said the paste remains something of a “gray area” for kosher winemakers like himself.