Ask Wine Wizard

Pressing seeds, gluten in wine: Wine Wizard



Wine and gluten allergy
Can you tell me if typical wines in the store contain gluten or if certain yeasts contain gluten? Gluten is a protein in wheat, barley, rye and oats. If any of these grains are used to carry or grow the yeast, I would think the wine would have enough of the protein to trigger the allergy.
Bob McKee
Tucker, Georgia

I myself don’t suffer from Celiac Disease, nor am I gluten sensitive so I’ve never had to even think about this issue, though I know a lot of other people do.         
For readers who may not know, gluten is a protein found in wheat and other grain products. A certain percentage of the population has what’s called Celiac Disease and suffer an adverse immune response whenever they ingest gluten. Symptoms can range from poor nutrient absorption to diarrhea to fatigue, and the condition often goes undiagnosed as the symptoms can be so easily confused with other issues. Those with the disease make a point of avoiding eating anything that may contain gluten and often spend quite a lot of time investigating “hidden” sources of gluten in their diet. It’s easy to give up the baguette and bagels but not so easy to avoid gluten when it’s historically been used even in non-food items — like the old kind of lickable stamps!
To investigate gluten in wine yeast I put in a call to my friendly neighborhood yeast supplier, Scott Labs in Windsor, California, and found out that Lallemand, the company I tend to patronize when I purchase my yeast through Scott, has paperwork that shows that they do not use any grain products in developing their yeast cultures and that their yeast cultures are gluten free. If you are truly concerned I would certainly try to get ahold of a customer service person at your yeast company of choice.
As for gluten in commercial wine, I’ve read that some wineries are able to certify that their wines are gluten free if you call their customer service number. Even so, I’m really not worried about gluten being in wine in the first place. While wine certainly does contain a small amount of dissolved protein (naturally coming from the grapes — grapes do not contain gluten), winemakers typically do not add products that contain gluten to wine. For example, I’ve never heard of fining with grain protein. I’ve read some pretty panicked posts on the Internet about fear of barrel-makers using a wheat-based paste on the barrel heads during barrel construction. I’m not sure if any barrel-makers still do this (I heard about it as a college student as a very “old school” way to make a barrel — these days coopers use more-sanitary paraffin wax) but you can always call the barrel company.
If you want to avoid gluten in wine from this possible (but in my opinion highly unlikely) source, stick to wines that probably haven’t seen any barrel time, like young non-Chardonnay white wines under $12.00/bottle. I give a price point reference because using barrels is expensive (and barrel-aged wines tend to be subsequently more expensive) and is traditional mainly in Chardonnay, not in stainless-steel fermented and aged types  of wine like Sauvignon Blanc, Riesling and Pinot Grigio.
Beware of commercial wines being marketed heavily as “gluten free.” The American Dietetic Association considers wine and most alcoholic spirits to be safe and so wines hyping their “gluten free” status may be just trying to find a unique marketing angle. However, since I’m not a doctor, I encourage everyone with Celiac Disease to do your own research. If you have a sample of wine you’d like to test for gluten, food analytical labs, like EMSL Analytical Inc. (www.foodtestinglab.com, 866-798-1089) will accept samples to test — for a fee of course. 



Heavy pressure
When pressing my grapes I am aware that pressing the seeds can result in undesirable flavors in the wine. I have always been careful not to over-press my grapes but this year I pressed until the pulp was dry then examined it and there didn’t appear to be any broken seeds in the pulp. Is it possible to exert enough pressure with the typical home basket press, to rupture the seeds?
Brian Aziz
via email

I’m so pleased you’re paying such attention to detail in your winemaking. Absolutely we need to be concerned about extracting bitter seed tannins in our wines and during pressing we must certainly be vigilant. This is when the pressure of pressing can sometimes extract a number of bitter phenolics from seeds and skins; a few of these compounds can contribute extra tannin and “grip” to a wine, but too much can push a wine over a bitter and gritty cliff!
This is why, towards the end of pressing, many winemakers take a “press cut” to separate out the last 10–20% or so of the wine that comes out of the press. Often we’ll add it all back in, but it’s nice to be able to keep it separate for later evaluation. Taking press cuts allows you more control in the balance between wanting to make sure you squeeze out every last drop but also wanting to be left with the best wine possible.
You’re also on to something when you’re guessing that a typical home basket press is actually a pretty gentle way to separate the skins and seeds from your new wine. There is a reason that many uber-premium wineries, especially those that specialize in Pinot Noir, have spent many thousands of dollars for the new generation of “traditional” 3–8 ton basket presses for their fine wines. The typical commercial bladder press (which inflates a big balloon inside a big metal drum, pushing the must to one side against interior drainage channels) can reach pressures of 2 bar or more so winemakers can, as a buddy of mine says, “squeeze the snot out of the grapes,” not that you would want to. While there’s no way that a typical home basket press can reach those kinds of pressures, I still do recommend winemakers keep a sharp eye (and sharp tastebuds) on the wine (or juice) that comes out toward the end of pressing. Even if no seeds are broken (they’re pretty strong little nuggets and rarely “rupture” even in commercial-sized presses), a good hard last squeezing on the ol’ basket press can still cause some bitter and phenolic liquid to come out.