Friday, January 9, 2009

Distilling the facts about Distillation

The last 24 hours have been interesting for me, gastrointestinally speaking. Last night, Kelli made a delicious batch of sugar cookies from scratch. A short time after eating a few cookies from the first batch, I had a reaction that was suspiciously reminiscent of a gluten cross-contamination episode. The funny thing was, there was no gluten in the recipe, and we don't have gluten-containing products in the house...or so we thought. It turns out we had a traitor lurking in our midst, hiding in plain sight in our spice cupboard.

The offending product was supermarket-brand almond extract, which I had bought while grocery shopping earlier in the week. The problem, it turns out, is not the almond, but rather the alcohol listed on the ingredients list for the extract. (If you read our post about the hidden source of gluten contamination at our Whole Foods cooking demonstration back in 2008, I feel stronger than ever that the problem then was the brand X vanilla extract, which would have had the same problem - gluten-contaminated alcohol used in the extract.) Allow me to explain.

First, let me make clear that this is a discussion about distilled alcohols. Fermented alcohols such as wine and beer are another story entirely, and don't pertain to this discussion. We're talking here about distilled spirits, which include most vinegars, as well as many of your harder liquors - vodka, gin, brandy, scotch, whiskey. When it comes to answering the basic question - Is there gluten in my distilled spirits? - the answer should be cut and dry, yes or no. Unfortunately, there are many shades of gray, and it all comes down to the very dissatisfying answer: it depends. Here's why...

At the outset, it's important to ask whether or not the source grain for your alcohol is one that contains gluten in the first place. If we're talking about corn-based or potato-based or rice-based alcohols, then gluten isn't present in the grain, and therefore, also shouldn't be present in the alcohol derived from that grain. (Most vinegars are made from red or white wine, apple cider, or rice wine, so they're all safe. The exception is malt vinegar, which both contains barley AND is typically not distilled. Hence, malt vinegar is NOT gluten-free.) But what if the source grain is something like wheat, which is chock full of gluten?

For years, there was debate as to whether or not the distillation process removed gluten and left us with a gluten-free alcohol. The science of the distillation process is sound - distillation does remove gluten from a grain alcohol. More accurately, distillation leaves the gluten behind. Distillation is a process whereby two or more liquids with differential boiling points are separated from one another. The mixture is heated to the boiling temperature for the lowest-boiling-point liquid, which becomes a gas and is subsequently condensed. Because alcohol has a relatively low boiling point, it boils off first and leaves the gluten behind. When it later condenses, you're left with a purified alcohol free of gluten. (Also, the more distillations an alcohol undergoes, the purer it becomes.)

However, we know from overwhelming numbers of anecdotes that people with Celiac Disease or especially sensitive cases of gluten intolerance may still have a reaction when consuming distilled spirits that should be gluten-free. Tests have subsequently confirmed that gluten is sometimes found in certain distilled spirits. The fault, though, is not with the distillation process. The theory and the science there are sound. The problem is with the practice of distillation in a real world setting.

For one, although distillation removes gluten from gluten-containing spirits, the source grains may still be present in the facility, and present the possibility for cross-contaminating the gluten-free final product post-distillation. (This is the same reason why GF beers should be brewed in a dedicated facility, so as to avoid cross-contamination with barley and wheat used for other beers.)

Secondly, distillation can't solve the problem of ingredients added to an alcohol after the distillation process. Those ingredients, added later, may include barley malt or colorings or flavorings that contain gluten (this is sometimes the case with certain vodkas, brandy, scotch, whiskey and gin).

In the end, then, what are we to do? You have several options: 1) use only extracts, vinegars and spirits that are labeled as gluten-free (such as the Rodelle Vanilla Extract). 2) contact the manufacturer of a product and find out the source grain for their alcohol and other ingredients. 3) If you're a gambler, you can try different products and see how your body reacts to them. (For me, this hit-or-miss gastrointestinal version of Russian Roulette isn't worth the consequence.)

The biggest lesson, perhaps, is that when it comes to distilled spirits (and extracts and vinegars), the best posture is one of buyer beware. Products that are labeled as gluten-free inspire a welcomed level of confidence, and once you find a product that works, stick with it!

- Pete


Phoebe said...

What a fascinating post! I like the alcohol free vanilla that is in glycerin mostly because I just don't like the extra alcohol. You don't mention this in your article, so I'm wondering if you have ever tried it.

I assume you know to check your baking powder for hidden sources of gluten? I always get the GF kind.

Phoebe said...

Oops, should have read your post more closely. The offending item was the almond extract! Perhaps just substitute your almond extract with GF vanilla extract next time?

Also, I know for me that refined sugars and flours, even if gluten free, will cause me gastrointestinal distress if I over do it.

Lauren Denneson said...

You know, I have been noticing that I can't drink whiskey and without getting sick (but fine with wine and GF beers) and I thought I was perhaps sensitive to something else in the grain in addition to the gluten. Your thoughts about cross-contamination and the carefulness with which the distillation process is completed makes a lot of sense. If you've noticed this kind of stuff with extracts, then I guess I'm not going crazy! Thanks for the post!

peterbronski said...

Hi Phoebe,

The distilled alcohol in the extracts (vanilla, almond, or otherwise) are the problem for me - as long as they're GF, then I'm in the clear.

Hi Lauren,

You're not alone. I know lots of folks with CD who have problems with certain hard liquors - vodka seems to come up more often than others, but whisky and other liquors can be problematic as well!

Cheers, Pete

GFE--gluten free easily said...

A very well done article, Pete! I missed this one the other day. As far as extracts, I make my own vanilla extract and use that almost always even when another extract is called for. Homemade vanilla extract is much more flavorful, economical, and most importantly, I know exactly what goes in it. I have used one brand of grain-based distilled vodka as the base without issue, but most often I use potato vodka.

Your point on the cross contamination after the distillation process is a great one. Of course, I knew about flavoring added afterwards being a concern, but did not think about that being a concern to the non-flavored varieties or about the gluten that is removed in distillation still being around to cause issues. Examples like these always make me wish for gluten-FREE testing and I mean FREE (no 20 ppm or even 10 ppm) of all products.

Thanks for the article and sorry for being blindsided by the extract!

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Tammie T said...

Hi Pete, Thank you for such a great anecdote about gluten contamination. I have followed your advice and contacted manufacturers to determine source grains in a variety of products from condiments that list "vinegar" as an ingredient, to distilled spirits, to extracts. I do not want to play Russian Roulette with my gut, but in the real world setting have found that I'm playing roulette anyway! Many companies label their products gluten free, but I still get sick. Is it a coincidence that distilled vinegar is often an ingredient in the offending product? I'd also like to mention that the culprit in some distilled spirits could be the caramel color (such as brandy or whiskeys...) Also I am interested to know your opinion of Three Olives Vodka. Their website claims that they are gluten free and wheat free, yet the grain used is wheat. I feel this is false advertising...You?

peterbronski said...

Hi Tammie... Distilled vinegars are both a) distilled and b) made from gluten-free ingredients (such as grapes, apples, or rice), so in my opinion, you don't need to be checking with companies about distilled vinegar as an ingredient. That's not likely to be causing your problem.

The Three Olives website only goes so far as to say the vodka is gluten-free. They make no wheat-free claim that I've seen. These days it's widely accepted that distillation does remove gluten from spirits such as vodka, so their claim is reasonable. Of course, a long overdue GF labeling standard in the United States would help...

Cheers, Pete

Bruce said...

Thanks for the post on an interesting topic about which there is a lot of confusion. I have always played it safe by avoiding distillates, but I am always hopeful for new information.

I am puzzled by one of your comments. You write "When it later condenses, you're left with a purified alcohol free of gluten." Then you add " (Also, the more distillations an alcohol undergoes, the purer it becomes.)"

This is contradictory. If the first distillate is free of gluten it can not become any more free by further distillations. Which of your two statements is the correct one?

peterbronski said...


Though seemingly contradictory, both statements are correct. As a heavy protein, gluten is considered non-volatile, so it doesn't come through in the distillate. But multiple distillations DO produce a purer alcohol. For example, multiple distillations are used to produce spirits with higher concentrations of alcohol, or to develop more neutral flavors free of other volatile compounds that came through in earlier distillations.