Amy Jones, MS, RD, Lisa Almenoff, MS, RD, Luke Emerson-Mason (Bia Diagnostics), Thomas Grace (Bia Diagnostics), Kristin Voorhees (NFCA), Cheryl McEvoy (NFCA) and FA (winery) contributed to the birth of this article.

Bottom Line: Two bottles of wine aged in oak barrels sealed with a wheat flour paste were tested for gluten using both the sandwich and competitive R5 ELISA. All results were below the lower limit of quantification for gluten for these assays of 5 and 10 parts per million, respectively.

The TTB and Gluten-Free Labeling of Alcohol

On May 24th 2012 the Tobacco Tax and Trade Bureau (TTB) released an interim policy on the labeling of alcoholic beverages under its jurisdiction. The TTB regulates almost all alcoholic beverages. Exceptions include beer made without malted barley, wines containing less than 7% alcohol by volume, and hard ciders containing less than 7% alcohol by volume. The aforementioned beverages are regulated by the Food and Drug Administration.

In the past, the TTB has not allowed gluten-free claims on beverages under their jurisdiction stating the following to me in written correspondence, “The Bureau considers labels that declare a product to be “gluten free” or lead to the impression that a product is safe for those who suffer from celiac disease as making health claims, which are prohibited.”

The new TTB policy contains several changes and clarifications regarding the labeling of alcoholic beverages. This has been driven in part by the beverage industry, some of whom wish to include gluten-free claims on product packaging.

Under the Interim Policy on Gluten Content Statements in the Labeling and Advertising of Wines, Distilled Spirits, and Malt Beverages, the TTB will not allow gluten-free claims to be included on product labels or in product advertising if the alcohol is made with wheat, barley, rye, or crossbred varieties of these grains OR any ingredients derived from these grains. This means that traditional beer made with barley malt can NOT be labeled or advertised as gluten-free. Distilled alcohol that uses wheat, barley, or rye as a starting material can NOT be labeled or advertised as gluten-free.

The Interim Policy goes on to state, “Many alcohol beverage products subject to the FAA Act are produced without any ingredients that contain gluten. For example, a wine fermented from grapes, or a vodka distilled from potatoes, may be “gluten-free” if the producer used good manufacturing practices, took adequate precautions to prevent cross-contamination, and did not use additives, yeast, or storage materials that contained gluten. Under this interim policy, TTB will allow the use of a “gluten-free” claim in the labeling and advertising of such products. As always, it will be the responsibility of the importer or bottler of the product to ensure that the claim is truthful and accurate.”

Based on my interpretation of the policy (refer to bolded section), a vintner would NOT be able to label a wine gluten-free if the product was aged (stored) in oak barrels sealed with a gluten-containing flour paste.

Aging Wine

According to the winery we communicated with, it is standard practice in the wine barrel making business to seal the tops of barrels with a flour paste. We were also told the following:

1. In general, red wines such as Cabernet Sauvignon, Merlot, Zinfandel and red blends at a price point equal or higher than $12.00 tend to be aged a little longer and in actual oak barrels.

2. All wine barrels are made of one oak species which is white oak.

3. Aging wine in barrels is still a widely used practice, although many wineries use barrel alternatives.

4. It is a standard practice in the wine cooperage business to seal the heads of barrels with a flour paste.

5. The staves of the barrels do not need any type of sealant.

6. The amount of flour paste to seal the barrel heads is minimal.

7. Using barrel alternatives for aging wine eliminates the need for the flour paste.

8. However, it is common for wineries to create the final wine blend with a percentage of wine aged in barrels blended with wine aged in barrel alternatives.


The winery told us the two wines they make that contain the highest percentage of wine aged in oak barrels—Cabernet Sauvignon and Merlot. One bottle of each of these wines was purchased from a mail-order company and shipped directly to Bia Diagnostics for testing. Each bottle was tested using the sandwich R5 ELISA (R7001) with cocktail extraction (R7006) and the competitive R5 ELISA (R7021). All tests were run in duplicate (2 extractions).

Cabernet Sauvignon

Sandwich R5 ELISA extraction 1: < 5 ppm gluten

Sandwich R5 ELISA extraction 2: < 5 ppm gluten

Competitive R5 ELISA extraction 1: < 10 ppm gluten

Competitive R5 ELISA extraction 2: < 10 ppm gluten


Sandwich R5 ELISA extraction 1: < 5 ppm gluten

Sandwich R5 ELISA extraction 2: < 5 ppm gluten

Competitive R5 ELISA extraction 1: < 10 ppm gluten

Competitive R5 ELISA extraction 2: < 10 ppm gluten

Why Both the Sandwich and Competitive R5 ELISAs Were Used

Wine is a fermented product. When testing a product that has been fermented the competitive ELISA should be used. This is because protein that has gone through fermentation may become hydrolyzed (broken down). If one of the starting materials in an alcohol is wheat, barley, or rye OR if there is concern that contamination may have occurred prior to fermentation OR if hydrolyzed gluten is used as a fining agent, it is very important to use the competitive R5 ELISA. That said, both the Food and Drug Administration and the TTB believe that currently there are no validated methods available to accurately assess the gluten content of fermented products. This is because the competitive R5 ELISA has not been formally validated in a multi-laboratory ring trial.

In the case of wine aged in oak barrels sealed with a wheat flour paste, the situation is somewhat different. Any wheat that might leach into the wine would not be fermented or hydrolyzed. The sandwich R5 ELISA should be able to accurately assess gluten that may have made its way into wine as a result of being aged in this manner.

My Thoughts

Wine has always been considered naturally gluten-free. Wine aged in oak barrels sealed with wheat paste appears to be gluten-free. Because the possibility of gluten in wine is an issue that consumers are slowly becoming aware of, it is important for vintners to be fully transparent about their practices. However, the TTB should consider allowing wine aged in oak barrels sealed with a gluten-containing paste to be labeled gluten-free based on testing with the sandwich R5 ELISA. Because wine is a fermented product, the competitive ELISA also can be used to help ensure that hydrolyzed gluten protein is not present in the final product at levels considered harmful to individuals with celiac disease.

The TTB policy statement is available at

© 2012 by Tricia Thompson, MS, RD. All rights reserved. This article may not be reprinted, reposted, or republished without the express written permission of Tricia Thompson.

Gluten Content of Wine Aged in Oak Barrels Sealed with Wheat Paste