Education,Organic,Wine,Wine Making

Understanding sulfites’ role in wines

Véronique Raskin and I have embarked on a journey that has to do with organic wines. And, we really got things going…. That I know for sure. When I saw a link coming in from Italy, I knew that this is huge.

Meanwhile, Véronique also knows that this is her moment to finally get out that which has been rattling around her brain since the 80s… At first, she was so gung-ho that someone was finally listening, that we just nailed it with a title that sent shock waves rippling, with The shocking truths behind organic wines in the United States… In that first installment came a bit of a stall. Véronique was not only going to disclose some long-held truths that hadn’t yet seen the light of day, be she was also realizing to do so, it must be handled delicately. The delicate part is what’s put it into a “how do I do this, so that only the truths will be revealed and remove all of the emotion?” She wants history, she doesn’t want to defame anyone or anything in the process.

So here we are. She’s got the next part of the story and has to edit it… I’ve got people greatly interested and I’m holding back the tide…

Which brings me to a great insert…

I just got the following Email, and I asked permission to use it for today’s blog from Jim Lapsley. Here it is.

Dear Jo,

I’m writing with a question and a comment.

The question:  When are we getting the rest of Véronique’s story?  Having been a participant in the early days of organic wine in California, and an acquaintance of Véronique’s, I am curious to read her version of past events.

The comment:  In response to a comment on the first story you wrote that “Sulfites are a natural occurrence on wine grapes” which really isn’t correct.  The grapes don’t produce sulfites and the sulfites aren’t on the grapes.  I think it is important to get this right especially if the discussion gets into sulfite additions. There is too much misinformation out there that we don’t need to add more.

Sulfites sometimes (although definitely not always) are produced in small quantities (10-20ppm) by yeast during alcoholic fermentation, although the sulfites quickly bind with oxygen and aldehyde so that the amount produced by yeast is not reactive.  Like most living organisms, grapevines produced amino acids for cell growth, and some amino acids (cystine, for instance) contain sulfur atoms.  If the cystine is broken down, the sulfur is released and can react, which is probably the source of sulfites (as well as hydrogen sulfide).

Using current analytical methods, the detectable level for sulfites in wine is about 5ppm (or was a decade ago).  When the sulfite labeling law was put into effect back in the 1980s, the limit was about 10ppm, which is why that number is listed as the action level in the labeling law.  During my roughly 10 years of organic wine production from 1991-2001, producing 3 to 4 red wines a year from organically grown grapes at Orleans Hill, I had my wines analyzed by ETS Labs in St. Helena in order to make label claims.  Every red wine came back “less than 5ppm”.  The wines may have had some sulfites–we can’t know–but if so, they were below level of detection.

I also made a no-sulfite added organic Chardonnay which was cold-fermented.  These wines always had some detectable sulfites following fermentation (although in most years the amount was below 10ppm–the highest was 23ppm one year).  I suspect, but don’t know, that the cold fermentation stressed the yeast, causing cystine breakdown and Sulfite formation.

My point in the above is that although it is true that yeast can produce sulfite in wine, yeast don’t always do so, so repeating the rather common assertion that sulfites naturally occur during fermentation is, at best misleading.

If you have any questions on the above, I’d be happy to respond.

I’m sending this to you via personal email, rather than as a post on your blog, because I respect you as an industry veteran and think this discussion is better conducted off-line.

Best regards,

Jim Lapsley

Additionally (second Email allowing me to use his information)…

Tony Norskog, who also produced “organic” (organically grown, no-sulfite added) wines (mostly for his “Daily Red” label) and who purchased the Orleans Hill brand from me when I quit commercial production in 2002, has even more years of experience producing organic wines than do I.  His experience is similar to mine in that the vast majority of his red wines contained “not detectable” levels of sulfites.  I am copying him on this email so that you will have Tony’s email, and perhaps Tony can add a bit of his own experience.

Certainly sulfites can be produced by yeasts (assuming there is a sulfur atom somewhere in the mix), but the assertion that this is usual is not born out in my experience, at least with red wines.  My colleagues at UCD sometimes still make the claim, and I generally ask “backed up with what data?”

Another issue, which hasn’t yet come up in the discussion, is the form of the sulfite.  SO2, when added to an acidic medium like wine, disassociates a proton (H+) so that most of the “sulfite” is in an ionic form and should be referred to as the “bisulfite ion.”   This is what winemakers refer to as “free SO2″ because it is “free” to react with compounds, such as aldehyde or oxygen.  Once it reacts, it forms a larger molecule of some kind (depending upon what it has bound with) and is referred to as “bound SO2.”  Together the “free” and the “bound” are referred to as “total” SO2, which is what the TTB wants measured.  Winemakers mostly want to know the level of free SO2, since that is what provides protection to the wine.  It is probably the free SO2 that people with asthma react to (although I am not sure of that and am not a medical doctor).

If yeast produce some SO2 during the fermentation process, which also produces lots of intermediate compounds on the road to converting sugar to alcohol, almost ALL of the SO2 produced by yeast quickly binds with other compounds.  That is why most winemakers add SO2 to wine once the fermentation is complete.

Who is Jim Lapsley and how we can trust his information?

(From a UC Davis pdf)

James Lapsley
Dr. Lapsley is an internationally known author, winemaker, and instructor. His main areas of research are the economics of wine production and marketing, and the history of California wine.  He is an Emeritus Continuing Educator, having retired from UC Davis University Extension in 2009. In retirement, he works 30 percent as a Researcher at the University of California’s Agricultural Issues Center and as an Adjunct Associate Professor in the Department of Viticulture and Enology at UC Davis, where he
co-instructs a class on wine economics each spring.

Lapsley has authored Bottled Poetry, a history of the emergence of the Napa Valley as it evolved into California’s premiere wine region. He co-edited, along with Kirby Mouton, Successful Wine Marketing, which was awarded the OIV Grand Prize in 2001 for the Best Book on Wine Economics. From 1980 to 2002, Lapsley was President and Winemaker for Orleans Hill Winery, which specialized in wine produced from organically grown grapes. In 2003, he was a Fulbright Scholar in Uruguay, where he collaborated with faculty in the Schools of Chemistry and Agronomy to create a much-needed degree program in enology.

Since his retirement in 2009 from University Extension, Lapsley has been active in research on California wine economics and has authored or coauthored the following articles: “Grapevines of Innovation: Ozone as a Cleaning Agent in the California wine Industry” Calanit Baram, Jim Lapsley, Rolf Mueller, and Dan Sumner, Journal of Wine Economics, Vol. 7, #1, 2012; “Economics of Wine Import Duty and Excise Tax Drawbacks,” Daniel A. Sumner, James T. Lapsley, and John Thomas Rosen-Molina, Agricultural and Resource Economics Update, Giannini Foundation, Vol. 15, #4, May 2012; “The Introduction and Dispersal of Vitis Viniferainto California: A Case Study of the Interaction of People, Plants, Economics, and Environment,” in Biodiversity in Agriculture, Gepts et al., Cambridge University Press, 2012; “O’Neill Vintners,” case study and presentationfor the UC Davis College of Agriculture Agribusiness Executive Seminar, Monterey, March 5, 2012; “Too Much of a Good Thing? Causes and Consequences of Increases in Sugar Content of California WineGrapes,” Julian M. Alston, Kate B. Fuller, James T. Lapsley, and George Soleas, Journal of Wine Economics, Vol. 6, #2, 2011; “ Economic Implications of the Import Duty and Excise Tax Drawback for Wine Imported into the United States,” Daniel A. Sumner, James T. Lapsley, and John Thomas Rosen-Molina. Report by Agricultural Issues Center, August 20, 2011; “Looking Forward: Imagining the Market of California Wine in 2030,” Agricultural and Resource Economics Update, Giannini Foundation, Vol. 13, #6, July 2010 (Originally presented as a lecture at the pre-meeting symposium for the American Association of Wine Economists 4th Annual Meeting, Davis, CA, June 26, 2010). Lapsley is currently researching the first California wine boom of the 1880s as well as studying the life-cycle of wine firms from 1980 to 2010.

5 Responses to “Understanding sulfites’ role in wines”

  1. Step13 says:

    That’s really an interesting article about the sulfites’ role in wine. I’m allergic to the sulfites in wine and in particular in vinegar. Usually, I avoid drinking above all white wine and some types of red wine, anyway I noticed that few wine brands, those that maybe make a restrained use of sulfites give me no problems. Do you know on the basis of what the sulfites quantity is calculated?


  2. Jo Diaz says:

    It’s parts per million. Organic wines are 10 parts per million…

  3. Malcolm says:

    I suggest you read what Prof Roger Boulton et al. have to say in their book, Principles and Practices of Winemaking, regarding the speed of reaction between oxygen and sulfites. This is not rapid. On p 465 in the 1996 they state that the reaction is slow with a half-life of approx. 30 days. The reaction of sulfites with aldehydes is fast, as it is with ascorbic acid. More importantly with respect to wine sulfite also reacts with hydrogen peroxide which is a reaction product from the reaction of phenols with oxygen, catalysed by ferrous ions. As Boulton et al. state, “ …. The almost nonexistent oxygen removal capacity of sulphur dioxide under wine pH and ethanol conditions.”
    Do a search for an article entitled “On sulfites, wine and headaches, and the misconceptions that exist” that was on Pennlive.com for more interesting comments such as Also, as the post pointed out, most scientific evidence points to the fact that the greatest population at risk for
    sulfite headaches are asthmatics. I think most people believe sulfur dioxide causes headaches due to a widespread misinformed 60 Minutes episode back in the ’90s (I believe that’s what the cause was – may have to do some digging on this one). Also, that was at a time where the overuse of SO2 ran rapid in restaurant salad bars. It would be routinely sprayed on lettuce to keep it white.

    Usage is based on the need to protect the wine from oxidation and microbial activity. The actual level depends on the wine pH, wine type, wine makers preferences and so on.
    Also read http://www.unito.it/unitoWAR/ShowBinary/FSRepo/D106/Allegati/pubblicazioni/QSVE31/WATERHOUSE.pdf

    Also sulfites are not normally found or used in quality vinegar. If it is there is should be at a very low level due to the low pH of vinegar which shifts the sulfite equilibrium towards the microbiologically active molecular form. I have produced millions of litres of vinegar commercially and never used sulfites in the production of it. However you will commonly find sulfites in dried fruit for example.

  4. Jo Diaz says:

    thanks, Malcolm. You’re also correct on the salad bar usage. Veronique has explained this one to me, and it’s where we’re headed with her next addition to her story.

  5. […] Understanding sulfites’ role in wines […]

Leave a Reply