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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