The Problem of Gluten in Wine

Over the past few years, I’ve had several people ask me about gluten in wine. Grapes don’t contain gluten, of course, but gluten-intolerant people do have reasonable reasons to be asking the question.

Wheat paste – made from wheat flour, which does contain gluten – is used to seal the inside of some oak barrels. Some wine is aged in oak barrels, where it could potentially come into  contact with the wheat paste. Therefore, some barrel-aged wine could, potentially, contain gluten. Does this mean that people with severe gluten intolerance or gluten allergies need to avoid (barrel-aged) wine?

While I’ve seen plenty of gluten intolerance-related websites and forums pose and attempt answers to this question, I’ve had trouble taking them seriously. Logic and reason are useful tools, but sometimes scientific evidence turns even the best reasoning on its head. We can all speculate on what sounds reasonable, but some data would be nice.

An experimental report with something to say on the topic was published this year in the Journal of Agricultural and Food Chemistry. (It should be noted that a previous article commented on gluten sensitivity and wine, but the article was published in 2003 in a much less well-known publication – the International Journal of Tissue Reactions – to which I don’t have institutional access.)

Unfortunately, the article, “Immunological and Mass Spectrometry Detection of Residual Proteins in Gluten-Fined Wines,” doesn’t speak to the question of wines aged in wheat paste-sealed oak barrels, but to of residual gluten in wines that use gluten for fining – that is, clarified of yeast cells and other things that make wine cloudy – rather than. Fining agents, which also include such unpleasant-sounding if harmless substances as bentonite (a type of clay), egg white proteins, and isinglass (from fish bladders; yes, fish bladders), are added while the wine is still cloudy and help yeast cells and proteins and other things that make wine cloudy settle to the bottom of the container. The now-clearer wine can be “racked” off the top, leaving the cloudy bits in the bottom along with the fining agent, of which there should be none left in the wine. People with food allergies can sometimes be really sensitive to really tiny, trace amounts of allergens, though, so it makes sense to test whether any trace bits of gluten could be hanging around in wine waiting to make a super-sensitive someone sick.

Something really important to note here. This study looked only at wine clarified with wheat gluten, not wine aged in oak barrels sealed with wheat paste. Definitely different things. Still, even looking for gluten reactivity in wine is a start.

The study used anti-gliadin and anti-prolamin antibodies as well as pooled sera from people with wheat allergies to probe wine, then looked directly for gluten proteins in the wine using mass spectrometry. Anti-gliadin and anti-prolamin antibodies (gliadin is a wheat prolamin, and prolamins are proteins found in grains) are formed by people with celiac disease and gluten allergies and have a lot to do with the symptoms of these diseases. Sera (plural of serum, which is blood minus the blood cells) from people with wheat allergies should include these antibodies, too, but might include types that the researchers hadn’t thought to include among the purified antibody selections.

I’m inclined to take issue with the methods this study uses. After mixing together the wine and gluten, the experimenters centrifuged the wine to remove the gluten. This is obviously not what usually happens in a winery (though a few wineries do use gigantic centrifuges for this purpose.) The strength of this study, though, is its use of both antibodies – a relatively direct measure of immune system reactivity – and mass spectrometry, which simply measures whether gluten proteins are present or absent.

The bottom line? These researchers DID find gluten proteins in wine that had been fined with wheat gluten. There is at least the possibility that people with celiac disease or severe gluten allergy will react to wine that has been exposed to gluten during processing. What we still don’t know, it seems, is how likely that possibility is.

*For the record, previous studies over the past ten-ish years have looked for gluten proteins in wine fined with gluten, but this was the first published report using both antibodies and the more sensitive mass spectrometry method.

**Using gluten to clarify wine is an interesting proposition in itself. Presently, both egg proteins and isinglass – a substance derived from fish bladders (yes, I said fish bladders, and I meant it) – are used for the same purpose. Both pose an issue for vegan wine drinkers, who won’t consume anything containing or made with animal-derived substances. The latter is a problem for vegetarians, too, and either might be problematic for people with severe allergies either to eggs or fish. Gluten, then, seems like a great alternative…save that it might cause problems for the gluten-intolerant even as it solves problems for vegans.

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9 thoughts on “The Problem of Gluten in Wine

  1. Sometimes when you centrifuge a substance it doesn’t contain enough of said substance to physically separate it out even though these small quantities can indeed be weighed accurately.

    So what you can do in that case is add a known quantity of the substance you want to quantify so there is enough to physically separate it for weighing. The actual amount present in such a sample is then the difference between what you added to the sample and what you got after centrifuging it.

    You also run controls, which contained no gluten but had it added so that you know if your procedure itself is flawed.

    This is a bit easier to understand if you see it done in the lab.

    I don’t know if that’s why the gluten was added for certain, but that would be my guess.

    People with a severe allergy to gluten would be well advised to avoid any wine that might have even a trace, however, of any substance to which they have a known histamine response. Someone with a severe allergy can experience a histamine response from trace amounts. In very severe cases, this can cause a severe drop in blood pressure, resulting in heart failure. This is definitely not something a truly allergic person should take any chances on.

    • Renee, in this case I’m quite sure that the gluten was added to the wine as a bona fide processing step, part of the experimental condition, not as a control for small quantities. This particular study (and every other study I’ve seen on gluten in wine) looked at the use of gluten as a clarifying or fining agent, so gluten was added to the wine specifically for this purpose. My biggest concern with the centrifugation step is that it doesn’t mimic how clarifying agents are removed in most wineries.

      Certainly, people with gluten allergies need to be especially careful of encountering trace amounts of their triggering allergen. I think that this issue is probably most relevant to people with gluten intolerances and/or celiac disease for whom there is likely some threshold below which micro amounts of gluten are unimportant.

  2. Call the company. That’s what I did, and that’s the only real way to find out what is in the product or how it was stored, handled, etc …

  3. As far as I know (commercial winemaker with Celiacs) Gluten/ wheat paste is not used as a fining agent. If it were it would be to remove tannins from wine (proteins precipitate tannins). I have been unable to locate a commercial fining agent with gluten, in conversation with other winemakers I have yet to find one that has heard of using wheat or gluten to fine wines.

    ON the subject of gluten contamination from barrels, after doing some calculations I’m dubious that they have much if any contribution. Especially with red wines since the tannins would precipitate the gluten and most would be racked off.

    Here’s a calcuation of how much wheat paste (flour) would need to be in contact with the wine to reach the 20PPM threshold (yes this is may be a too high limit but it is the standard)

    - A barrel holds 225L or ~225,000 G of wine. (59Gal or 472 lb)
    - High Gluten flour is 14% gluten by weight
    - cup of flour weighs in at 125G
    - to reach 20PPM would require at least 4.5g of Gluten or 1/4 cup of flour.

    Even for a new barrel (one that has been rinsed out thoroughly) that’s a lot of flour. Most of the what paste used is in the sealing groove at the head. Barrels I have disassembled do have a very thin film of flour deep in the sealing groove of the head that remains there through the life of the barrel… you’d be lucky to find a tablespoon’s worth of flour in the entire barrel.

    As far as I can tell I have never had a problem with a gluten reaction to wine.

    http://www.traditionaloven.com/conversions_of_measures/flour_volume_weight.html
    http://www.pizzatoday.com/Buckets/TomLehmann/gluten-is-important-to-dough

    • I completely agree with you, Steve. Yet, as someone with Celiac, I’m sure that you know how much discussion there is over how much gluten or exposure to gluten is enough to cause a problem for someone. Regardless of how much evidence says otherwise and regardless of who recommends what, I’m certain that people with sensitivities will continue to report on their own (subjective and unquantifiable) experiences. Still, your point is well-made.

  4. But what about grain tannins in wine? I’ve noticed wheat/grain tannins mentioned on labels, especially Australian wines.

    • Rick,
      Could you please let us know what brands you’ve seen these labels on? I’d like to contact them and find out what agents they are using.
      Your comment prompted me to do a bit more digging (the tannin part was the key). There is a procedure for using wheat bran (or hulls) as a fining agent for iron, this seems to be restricted to Whites and Rosés. Any gluten imparted by the fining would be below detectable levels, but possibly not below reaction levels. I will enquire with our suppliers about any agents that might use wheat bran; my last enquiry did not turn up anything that used any part of wheat but there isn’t much awareness in the wine community about celiacs.
      Thankfully our wines are minimally processed so we aren’t exposed.
      Thank you for the follow up.

  5. There’s an interesting study by Vojdani, “Detection of IgE, IgG, IgA and IgM antibodies against raw and
    processed food antigens” (www.nutritionandmetabolism.com/content/6/1/22), where one of his subjects with gluten tolerance shows high IgA and IgM reactivity to wine. It’s not specified which wine, it’s only indicated for one subject–we don’t know about the rest–and the subject also has egg sensitivity, but it’s interesting nonetheless.

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