At a doctor’s appointment late last year, I was told that I needed to cut gluten out of my diet. I said that would be no problem. I wasn’t eating bread at that time anyway, and there’s no gluten in bourbon.
The doctor stopped me and insisted that there is gluten in bourbon. His proof was that “they won’t put gluten free on the label.” Instead, he urged me to only drink Tito’s vodka. I assured him that gluten doesn’t carry over in the distillation process because it’s too heavy.
That was the end of it as far as I was concerned — until I spoke with a friend named Fred Ruffenach, who has celiac disease. When I first met Ruffenach a decade ago, he was still able to drink bourbon, but now his celiac has progressed to the point where he no longer can. He told me that some barrel manufacturers use a flour paste to seal the heads on the barrels, introducing gluten to an otherwise gluten-free spirit. The case was reopened, and I decided I needed to investigate, especially now that there’s a push to include nutrition information on the labels of distilled spirits.
Distilling Really Does Remove Gluten
Distillation is a process of purifying or stripping away unwanted components. When water is distilled, impurities are left behind. A similar process happens with alcohol, in that the alcohol vapors are removed from everything else and placed in a completely new container. The solid parts of a mash are too heavy to carry over with the alcohol vapors.
Gluten.org, which is run by the Gluten Intolerance Group, conducts food safety testing for those with gluten allergies and intolerances. The website features a page dedicated to fermentation and distillation that states that fermentation can break down some gluten proteins. However, those proteins do not appear in a distillate. “Proteins are heavy and gluten proteins are not volatile,” they explain, “so they should sink to the bottom rather than get siphoned off into the distilled liquid. The resulting distilled liquid becomes gluten-free.” They then corroborate Ruffenach’s explanation (somewhat) and warn that gluten can still be introduced into distilled spirits by beer-barrel finishing.
“You can have a wheat spirit that has no gluten in it, but people get confused by that,” says Catoctin Creek President and Distiller Becky Harris. “Wheat is in it, but the wheat has been transformed because you ferment the wheat, it turns into ethanol. You then distill it, and the gluten doesn’t actually come across. It’s removed completely by the distillation process. It’s not wheat, it’s ethanol. The gluten is part of the wheat, and it’s bound into the mash, as it were.”
Harris says that Catoctin Creek has tested their spirits before, and they were found to contain no gluten, but they don’t state that on the label because they aren’t testing every single batch they bottle.
“[To get gluten], you’d have to have mash actually going into the distillate, because it just doesn’t transfer,” Harris says. “I do tell folks, though, if they’re celiac or whatever, the risk is that we process something that doesn’t contain gluten in a place that does have gluten ingredients.”
What Would Have to Happen to Have Gluten in a Bottle of Whiskey?
Barrels are one of the most likely sources of potential gluten contamination in distilled spirits. Materials introduced into a barrel or directly into the whiskey can contain gluten, including in the beer-barrel finishing mentioned above. Bungs are traditionally made from poplar, which does not contain gluten, but some substances used to plug drill holes or even finishing woods can potentially contain gluten. Similarly, some flagging material used to fill leaks such as cattail reeds or certain pastes may contain gluten.
“The flour and water you mix together to make a paste, and that’s going to be painted around the chime of the barrel, where the head meets the barrel, which is the croze,” says Kelvin Cooperage Director of Sales and Marketing Brittany Hupp. “It’s kind of a preventative measure. If you’re racking your barrel and your barrel is going to leak, it’s mainly going to leak there at the joints where everything comes together. But we switched to Vycar, a food-grade sealant that’s gluten free, a few years ago.”
Hupp explains that there may be coopers at some distilleries and wineries that are still using a paste of flour and water to seal leaks in already filled barrels, but for the most part the barrel producers have moved away from that practice. She does note, however, that older used barrels potentially were made using flour to seal the heads.
“For us and most other new barrel cooperages, we use beeswax on the bead of the heads to help tightly set that joint, and a food-grade adhesive is applied to the exterior edge around the rim of the barrel after passing water and air testing,” says Zach Zimlich, operations manager at ZAK Cooperage. “Only a small number of barrels from a cooperage like ours would contain any flagging, and there isn’t a lot of flagging that is used in barrels.”
Zimlich says that he has heard of flour paste being used at the distillery level, but it has never been used at his third-generation family cooperage. He does know of some cooperages using flagging made from dried cattail reeds to repair joints and even in some cases to reinforce every joint, which could be a source of gluten contamination. To date, there is no clear answer as to whether cattails contain gluten, though some sources say parts of the cattail do contain gluten.
“The method of flour paste in water is still in practice, and the flour that is used is buckwheat, which contains no gluten.” says Andrew Wiehebrink, director of spirits innovation and research at Independent Stave. “We still do that to this day, and I am sure other cooperages still do, too. The material that goes on the barrel ends ultimately depends on the customer who is buying the barrel. Most cooperages have the capability to offer a few different solutions. Based on my experience, distilleries are fairly strict on approving materials that go on barrels. Most take pretty good care that everything is food grade, gluten free, kosher, etc. Wax is used as well on spirit barrels, but again, it all depends on the customer. There are so many different ways to do it, and some prefer not to use anything.”
Labeling Regulations and Gluten
In February of 2024, the Department of the Treasury recommended to its Tax and Trade Bureau (TTB) division that it initiate rulemaking around nutritional information on beverage alcohol labels.
Becky Harris volunteered to draft the letter that the American Craft Spirits Association (ACSA) sent to the TTB about potential beverage alcohol nutritional labeling laws. This meant that she needed to learn about food labeling laws and try to figure out how that might be applied to beverage alcohol labeling laws and then make an informed recommendation for how to apply regulations in a way that would both benefit consumers and not decimate craft distillers. These small businesses represent just 4.6% of the total volume of distilled spirits production in the United States.
During her research, Harris talked to numerous craft distillers to learn what they were currently doing, what they’d like to do, and what might be an undue burden if it were implemented in the future. Currently, there are regulations in place that allow beverage alcohol producers to include nutrition information on labels if they want to, but that has only been the case for a few short years and it is voluntary. Prior to that, beverage alcohol was not considered a nutritious product, and labeling it with nutritional information would have been considered a deception meant to make consumers believe that it was somehow nourishing.
“There were a few people who did it because they really wanted to be transparent,” Harris says. “The problem is that once you put it on the label, then they can test you on it. And a couple of the small businesses got into trouble. You basically can either send your stuff out and pay a couple thousand dollars to have it all tested, or you can put your ingredients in and there are some websites where it’ll come up with a label based on what your ingredients are. And if it’s not right, then you can get in trouble for that. So that is a concern from a small producer’s perspective.”
Unfortunately, Harris says, the government is not transparent about the standards and procedures by which nutritionally labeled items will be tested. What’s more, no one really knows when or if there will be any regulation requiring nutritional information on beverage alcohol products.
“Right now there is silence on that issue,” says Margie Lehrman, CEO of the ACSA. “There is no current proposal, it was simply a comment period as opposed to a formal notice to accept comments, even though the comments were due earlier this year, and they also had public hearings on this very topic. It was, I think, a method to address some of the pressure that’s been exerted on the executive office to get the TTB to move on this.”
When craft spirits producers were questioned, Lehrman says, it wasn’t so much that no one wanted to give consumers access to nutritional information but rather that they wanted to be able to give consumers that information in a way that wasn’t a financial burden.
“It’s whether it’s mandatory and how that access is gained,” Lehrman says. “A lot of our craft spirits producers pride themselves on the ability to turn out multiple versions of a whiskey in a year. And if you required on every single one of those bottles specific, really detailed nutritional labeling, it really would have sort of a quashing effect on the ability to innovate at the craft level.”
Harris says that the biggest calls for nutritional labeling are related to products that have things added to them. She found that people want to know, for example, that there’s sugar in a flavored product or what, exactly, has gone into an RTD. When it comes to straight whiskey, it’s usually simple enough to determine how many calories are in it if you know the ABV, which is required to be on the label.
However, whether or not a spirit has gluten contamination or is gluten free is a little cloudier. Should labeling one day require ingredients to be listed, also having “gluten free” on the label with a spirit that contains wheat or rye may only serve to confuse the average consumer.
The Safest Path
There are potential sources for gluten contamination in whiskey, as it turns out. Non-first-use barrels, particularly those from the wine or beer industries, could be a source. Having a bottling line, blending tank, or other post-maturation facility in the same room where grains are used or processed is another.
If you put “gluten free” on a bottle, you are liable for that information being accurate. For smaller producers, testing each and every batch of whiskey bottled can be extremely cost prohibitive. As long as producers are not required to make this claim one way or the other, omitting it will seem the safest path. While the lack of the label will decrease your market share among those looking for gluten-free spirits, it will also protect you from being held responsible in the event that gluten does make its way into one of your bottles.
We’re starting to see a shift in the big producers working toward cleaner, more sanitary factory environments with greater quality control than ever before. This may lead to the first gluten-free labeled bourbons and whiskeys as the industry adapts to evolving consumer demands.
