Friday, November 5, 2010

Sulphur in wine

The most controversial issue about natural wines - and the reason why they're of interest to so many people - is how much sulphur is used in the winemaking process. Purists say none should be used at all - although there is naturally occurring sulphur which will be detectable even in unsulphured wines. Many others reserve the right to use a small amount at bottling to stabilise the wine.

The problem is we have no idea how much sulphur winemakers are using - and won't unless the regulations change or someone decides to break ranks and put the amount they've used on the label (which I wish they would). The phrase 'contains sulphites' covers everything from miniscule to massive amounts. No help to those who react badly to sulphur and have maybe given up the pleasure of drinking wine as a result.

If you want to know more let me recommend this excellent post on which explains the issues with admirable clarity though they obviously have an agenda.

For a more technical approach check out my colleague Jamie Goode's site Wine Anorak here and here.

It's a subject I'm sure I'll be returning to but what's your view about sulphur in wine? Do you think a wine needs to be unsulphured to be classified as 'natural'? Should winemakers put the sulphur content on the label and can this be done in any meaningful way? Do you yourself suffer from allergic reactions to sulphur?


  1. I think winemakers should put on the label how much sulphur they poured in's useless knowing that a wine contains sulphites as they're also naturally produced..but the real deal is: will be they (winemakers) be willing to give those figures?!? Hard to say..

  2. This post (pretty inadvertantly) points to a lot which is wrong with the natural wine movement. Firstly, there are limits on how much sulphur can be added to wine. From memory in Australia it is 250ppm for table wine and 300ppm for sweeter (as in botrytised) styles. (realistically, any winemaker worth their salt or making decent wine doesn't get near this).

    Question is, do you want it quantified in your apple juice? Or your dried fruit too? Because 20 against a 10, it's probably in there...

    Beyond any of this, the 'natural = good' movement is surrounded by duff science. Case in point:

    Dear beloved antioxidants... giving people, umm, cancer.

    Speaking of cancer - you know what else has been shown (yet more convincingly) to provoke cancer? Acetaldehyde. You know where you get a shedload of acetaldehyde? Wines without sulphur. Because oxygen, err, oxidises alcohol to acetaldehyde. Not only does it taste like crap (bruised apple + bitterness), but it without doubt gives you a heckuva hangover.

    The idea that wines without sulphur might be more healthy (they're NATURAL!) is simplistic, and in many respects, not slightly correct.

    Surely what we should want from terroir is the best, clearest expression of fruit made wine. It is not the best fruit rendered worse by outmoded winemaking methods.

  3. Putting the amount of SO2 on the label would show us which producers are over zealous in their usage and which try harder to keep the product more 'natural'. However, if we tatsed two wines blind, one with 150mg/l and one with 40mg/l, would the average person tell the difference? Possibly if they were just bottled but prob not after a year or two. And how much is actually harmful?

    Also, putting the figure on the bottle might put consumers off. 100mg/l may sound like a lot to the uninitiated, but in fact it is only 100 parts in every 1,000,000! It depends how it is written.

    Remember, too, that 1000's of everyday foods use sulphur as a preservative and it does not seem to cause the same controversy and commotion as wine.

    I worked in AU's Hunter Valley and tasted some just bottles Semillon from an un-named producer. The first thing that hit my nose was sulphur and it was not pleasant - it also triggered a slight asthma flare-up! If putting the amount on the label discouraged overuse then it can only be a good thing, though we must be careful not to put people off.

    Tom Chamberlain

  4. Fiona, I love the subject you just raise, but it is a very complicated one. Many people, including wine blogger and retired bilingual journalist Michel Smith “gives out” to me because my posts are TOO LONG.
    So, I will cut this one into small pieces (“saucisonner” is the French for that).
    There are 3 main issues, and each will be addressed in turn:
    1) Are we allergic ? To what extent? What does it do?
    2) Which “sulphur”, how much, when ?
    3) Mention on the label
    I happen to qualify for answering the 3 topics: I used to be an MD in a remote past (with post-graduate education in chemistry and statistics as well), I’m now a full-time winemaker and I had to research medical litterature some 6-7 years ago on the topic of ....sulfite-allergy.

    Issue N° 1)

    Yes, we are all allergic to sulfites. But some are more allergic than others, especially those individuals with an “atopic” tendency, i.e. those who present other allergic manifestations, or chronic allergic diseases (asthma, Quincke’s oedema, atopic dermatitis, some inflammatory bowel diseases ... you name it). Allergy can manifest itself through various clinical signs, and by various physiopathologic pathways. Suffice it here to say you can have respiratory manifestations (tightness in the chest, wheezing, shortness of breath, or even full blown respiratory failure), skin manifestations (redness, sensation of heat, flare, itching, red spots ...), cardio-vascular symptoms (headache, irregular heartbeat = palpitations, intense vasodilation with blood pressure drop or even circulatory collapse) and digestive symptoms (diarrhoea, abdominal cramps, liver dysfunction).

    All of these are dependent upon your own sensitivity, the ingested dosis, the frequency (sensitization and desensitization effects) of exposure, .... We are only talking about ingested sulfites, here. Inhalation and skin contact also can led to problems.

    The classical picture, in most of us is: an itch in the throat or swollen lips, frontal headache with then extension to the whole skull (no migraine), sensation of heat, reddish cheeks, nose and forehead and .... a very difficult awakening the morning after. Mind you, excessive alcohol also plays a role in the picture.

    I will now stop by mentioning that many food components, and many drugs (including pharmaceuticals for injection) are treated with sulfites. Here follows a list (at random, but evocative): sea-food (oysters for instance), fruit (your basic fresh lemon or strawberries), canned soup (most tin cans, by the way), ham and sausage, vacuum-sealed lettuce, your typical British square tasteless supermarket loaf of bread, fruit juice, cider, beer (even the good Belgian ones), sauces (BBQ sauce, Worcestershire, ketchup, soy-sauce, wok dressing, mustard), even some aged rums (I swear) .... Endless list with thousands of items. Not just wine, you see.

    Should I now just pack it up, or do you want parts 2 and 3 .... on a later occasion ?

  5. There is no such thing as massive ammounts of sulphur. The maximum ammount is regulated by law, and that is still pretty low. Especially if one takes in account that maybe only say 1/2 bottle is consumed per person per day. Dried fruit for example may have 10 times more and one consumes a lot more and nobody cares. Anything above say, 40 ppm free tastes terrible so almost no winemaker uses more than that. 40 ppm free SO2 (maybe 100ppm total) is nothing really.

  6. It seems most of your readers are going to address issue N° 2, Fiona. It’s a good thing, it will spare me the effort. When they will have ... decanted, I might comment. I think most people with a real oenological education are too much of a chemist, and most basic wine-makers are not enough of a chemist, by and large. In Dutch, they would describe me as “noch vis, noch vlees” (similar to your “to be neither fish nor fowl”) and I might have interesting insights.

    So, issue N° 3 now.
    You suggest the wine-makers should state “how much they did pour”. Well, this doesn’t tell you much, I’m afraid. The various sulphur derivatives (whether you use gazeous SO2, metabisulfite, or aqueous diluted sulfite doesn’t do much to the point) find many ways to escape: during fermentation, during aging, yes, even after bottling (to a limited extent).
    They do so by evaporation (leave the system), by combination (bind to other wine constituents) or by oxydation to sulphuric rather than sulphurous compounds. Yes, purists will find a good many other ways still, but who cares.
    What you need to know is what is still in there, be it active (the free sulfites) or inactive (the bound sulfites). Trouble is, it is the sum of them that is detrimental to our well-being: the total sulfites. So, if you absolutely want a figure on the label: demand total sulfites. Other bloggers have commented on the various quantities and limits, with their own bias and prejudice.
    Here is my view:
    . “not a lot of sulfite” is between 0 and 40 mg/liter. It will probably do you no harm (directly, that is) if you don’t overindulge (up to one bottle each during a meal), except if you are really very allergic. But this figure says NOTHING about the active (free) form, if you want any. It will very likely be very low, but there is no way to guess.
    . “normal range” for dry wines with wine-makers who don’t insist on “natural” wines: anything between 40 and, say, 100 mg/L (which I begin to find quite high myself, but who am I?). But it doesn’t tell you anything about the active form. It may still be very low (especially if sulphur has been added several times in small quantities, not the best of systems if you ask me). We tend to use less in red wines, less in filtered wines, less in wines which have gone through the malo-lactic fermentation, less in bone-dry wines. Here, if you sip your entire bottle, you’ll very likely become aware of the presence of sulfites, to an extent depending on your own sensitivity.
    . “rather on the high side” is anything above 100 mg/L, but that is sometimes felt “necessary” in off-dry or even sweet wines. Most will not like the effect of more than a few glasses, I promise.
    Some of you might translate those doses into ”absorbed milligrams per kg of body weight” and so on, and compare it to European standards, Sterling Imperial standards, US norms, Deutsche Internazionale Normen .... Free to them.
    My conclusion is: it won’t help you much to know how much sulfite there actually is in the wine you’re drinking. But I have a strong view on one thing: if some claim there is none, it should be sincere, honest and verified.

  7. I'd like to echo Luc's last comment, and point out that wine is not entirely stable as a product. As it ages, SO2 will be consumed, for the most part. When you buy a bottle... who knows where it's going to be. That consumption is not super well understood, just as ageing of wine in general is a complex phenomena. But truly, for you to know the ratio of free to bound, you're really looking at buying yourself a rankine still and getting your titrate on.

  8. Phew! Many thanks, all for your input. (Luc, if that’s a couple of short comments, I can’t imagine what a long one would be ;-)
    They raise a lot of interesting issues some of which I’ll need to come back to in a subsequent post but a few I’ll comment on now.

    *Should other foods and drinks like apple juice state the amount of sulphur they contain too? I’d say yes. In fact unsulphured apricots are already marketed as such.

    *Is it hard to find a way of communicating this information and even arriving at definitions? Sure but that doesn’t mean that winemakers and the organisations that represent them shouldn’t try.

    *When I said ‘massive’ obviously that was a loose expression. I know there are legal limits but I think most people would be shocked to find how much sulphur is in off-dry and sweet wines, for example. I like Luc’s division of sulphur use into ‘not a lot’, ‘normal’ and ‘rather on the high side’. If one could find some way of codifying that I think most consumers would welcome it.

    *I raised sulphur because it’s at the heart of the debate about natural wines but I’m not fanatical about the issue. I want my wine to include enough to make it stable - and in the hands of the best natural winemakers that can be very little - but no more than is needed. I’d like the debate about the issue to encourage conventional winemakers to use less and regulatory bodies to consider reducing the limits

    *I don't think wine is singled out for special opprobrium here. On the contrary most food producers have to list their ingredients.

  9. Clearly individuals have different tolerances to sulphur levels just like many things – pollen, air pollution, cats. Back in the 1980s I certainly found most white Loire wines too much for me – I could smell the stuff.

    Having a legal term “low sulphur” may be a simple solution. If EU law permits 160 (for reds) up to 400 (sweet whites) mg/l then how about a range 16 to 40 mg/l for “low sulphur”.

    Agree that of the candidate list of natural winemaking practices then sulphur, possibly along with natural yeasts and addressing malolactic fermentation, are going to be the awkward areas. I would be happy to coin those wines (no added sulphur, yeasts or enzymes) as “extreme natural wines”.

  10. I'd like to address the point that Anonymous No2 made about Acetaldehyde.

    One big mistake most people make is to believe that sulfur dioxide prevents oxidation.

    Sulfur dioxide does not prevent oxidation from occurring. SO2 prevents further, more destructive oxidative reactions from occurring once oxidation has occurred.

    So therefore the presence of sulfur dioxide won't stop the oxidation of alcohol to Acetaldehyde.

    Secondly the main oxidisable compounds in wine are phenolics (like tannins) not alcohol.

    So this alleged connection between natural wine and cancer is simply NOT true and rather irresponsible one to make.

  11. Some good practical suggestions @Graham though I'm not sure all natural winemakers would welcome their wines being labelled 'extreme'.

    I've been wrestling with whether there should be a classification of wines on the blog similar to the one at Terroirs which flags up wines that are at the more uncompromising end of the spectrum together with ones that may be more in the comfort zone of conventional drinkers. Any thoughts about that?

    And I can't comment on the technical issues relating to acetaldehyde @Plamen and others but it does seem counterintuitive that a wine made with a minimum of additives should be more harmful than one in which many are deployed

  12. @Plamen You're right. Ish. It won't necessarily stop that initial oxidation (though does limit the activity of some oxidases), but what sulphur will do is bind strongly (and rapidly) to acetaldehyde, and render it odourless. Sulphur dioxide will also reverse diquinones back to diphenols. Molecular SO2 will also prevent the presence of H2O2 the wine (reducing it to H2O)from the oxidising of ethanol to ethanal (acetaldehyde). To get molecular activity you need a decent wack of sulphur (though this pH dependent, and more prevalent at low pH, hence Australia's reckless tartaric addition party it has every Feb-May [now that we've decided to use bags and bags of tartaric instead of bags and bags of sulphur]).

    You can get away without SO2 via certain things (malolactic will consume acetaldehyde, using inert gases [all the time, super-fastidiously etc]). But...

    Bottom line: having free sulphur means you won't have free acetaldehyde. You'll have hydroxy ethan sulphate.

    For me, I'm waaaaay more sensitive to acetaldehyde than I am to sulphur. I find acetaldehyde just unbearably vile. I don't think this is anything learned or pavlovian. I just can't handle that sweetness allied to bitterness (I also can't begin to deal with marzipan). I'm also waaaay more sensitive to the hangovers that it gives me - this is a pretty widely recognised phenomenon. I'm obviously aware that some folks are more sensitive to sulphur than I. And I am not advocating using sulphur by the truckload - any winemaker worth their salt making wine with decent fruit shouldn't have to revert to this (just as they shouldn't be adding tartaric ridiculously). Indeed, I'd be all for lowering the amounts of allowable SO2.

    As for no additive being more healthy... natural / unadulterated = healthy is an argument that I generally feel uncomfortable with (hence my inclination to weigh in here). I don't mean to seem belicose with it, but there are plenty of interventions or additions that are more healthful than we are without them. Modern life has its stresses and woes, but we should be grateful for certain advances, and we should most especially be grateful for understanding, and not rejecting, but possibly evading understanding is... not the way forward. I'm aware how much of a cranky technocrat I sound like saying that. But what I really mean is that I adore the idea of human knowledge collectively improving. It's one of our very best things, and a thing to be embraced.

    But what of ageworthy wines? I want wines that reach their peak after some time. I don't only want fresh wines. I like fresh wines. But I really, Really, REALLY adore what one gets from (most particularly) a white burgundy at the height of its powers. Or a Mosel with some years behind it. Can I get that from a natural wine? (I'm not being rhetorical - is it possible?)

  13. Cam Haskell, you know what the French say, you the English talk too much about it - just drink it and be jolly. ;-)

    But you know the bottom line is natural wines is that they are the TRUE terroir wines. By keeping the intervention as minimal as possible the winemaker allows for the grape juice to express itself truly.

    How many people here know that the flavours of gooseberries in New Zealand Sauvignon Blanc come from the type of foreign yeast they use? That flavour is not characteristic of the grape varietal.

    The natural yeast is very important element in preserving the character of the wine.

    I, sometimes, get annoyed from the fact that we have created a wrong preconception about these wines. Natural wine does NOT only mean wine made without adding of sulfur dioxide, there's a lot more to it.

    I am sure Fionna will cover it all with time.

  14. Fiona will definitely try! I really appreciate the quality of and thought behind these comments - you raise some important issues, Cam, which deserve addressing. What would be great is to taste a whole range of samples of the same wine with different additions - and none at all. Anyone volunteering?

  15. Is finding out how much sulphur is in a wine easy? Does the vigneron get their wine tested prior to bottling and do the test results show this? (I believe it shows the % alcohol level). I am aware of one vigneron who adds a really minute amount when the picked grapes first go into the 14 h/ltr cuve to 'kill off' any nasty things still there but that's it - everything else then happens naturally. How much is left after maceration/fermentation/decuving/aerating etc....?

    On that point and picking up on Fiona's post above, I would be interested in knowing whether an organic wine tastes any different to non organic wine. To explain, has any one who has followed a particular Domaine that has become certified organic noticed any difference in the wine pre and post certification. And if not, what then are the benefits other than a feel good factor that you are 'doing your thing' and the potential to raise the £ of your wine because it is now organic

  16. @Phamen You can talk too much about wine? Really?

    I'm not sure re: true terroir. This is because I think faults, to my mind, are troublesome because they mask terroir, and generally in a homogenising way.

    Obviously natural / sulphur free wines are not necessarily faulty. But they're riskier. And obviously sensitive, talented winemakers working with good fruit will be able to make it work. It's an interesting idea that one microbially mediated reaction is 'truer' than another. I'm not sure where I stand on that.

    As for gooseberry in kiwi Sauvignon, it IS a yeast mediated reaction. But it's reliant upon precursors in the grapes. For more, here (no paywall!):

    Marlborough Sauvignon has much more in the way of precursors - I'd wager if you were to conduct the most natural ferment in the world, you'd still get more gooseberry than you would from elsewhere.

    @Jem in Australia pretty much everyone who does your bottling will check SO2, or if you're doing it yourself you'll ensure there's enough kicking around (if working outside a sans-sulphur dioxide remit). Then to get an export certificate, it has to be independently analysed and meet certain criteria (not too much SO2, not too volatile etc).

    How much SO2 is left after ferment... is going to be a very varied answer. Just too many variables there to consider, in a ways. Saccharomyces cerevisiae is really THE species that is going to finish your ferment. Your strain might change. But it's your guy. And it'll produce SO2 naturally during fermentation. Other yeasts will start things early, but they're pretty much intolerant over anything near 6% alcohol.

    In my experience a lot of the organic wine made in Australia is more interesting. And very frequently better. And I think this is mostly a function of greater sensitivity toward the vineyard and what's going on out there.

  17. Thanks for picking up on Jem's points, Cam. On the does organic taste different one I haven't followed one wine closely enough to say whether going organic has made a difference to taste but winemakers have told me it does (well, they would, wouldn't they having made the huge investment in time and money going organic, but still . . . )

    Organic doesn't necessarily equate with good drinking of course any more than organic bread means good bread. But as Cam says, it's a question of a whole attitude to wine and a degree of attention to the vineyard that generally results in more complex and interesting wine.

  18. Cam/Fiona

    Thanks. I agree it is the attitude, the care that the winemaker takes with their vineyard that makes a difference. Good friends who have already posted elsewhere in another thread are thinking of getting formally certified as they beleive their good practice over the last 10/15 years means they are already bio/organic. But whilst it will maintain the differences they have made to the vineyard and reinforce their wine making principles, it is a potential ££ risk even though they have seen, and been told by the driver of the appellation's harvesting machine, that the quality and size of their harvest was far better than anyone elses in the region.

    Until the wine drinking public, and possibly the wine buyers too, have a better understanding of the benefits to the vineyard of being bio/organic etc and how these principles then carry though to/are embraced by the vigneron who makes the wine we will be faced with the situation where they continue to buy mass produced gloop from the supermarket.

    Some sort of 'study' would therefore be welcomed to look at the pre and post differences. Prehaps it's a topic for a MW dissertation.

  19. I'm sure someone will tackle it, Jem. BTW Jancis Robinson posted a piece on her site yesterday on a new book on biodynamic wine by Beverley Blanning which might interest you

  20. Looks like I'm too late for this conversation, which I still find interesting (after a couple of years of reading and commenting!). Just to say that I have't used any form of sulphur in the winery for the last 7 years and (touching wood here!) I haven't had a batch of wine go bad on me yet! As mentioned above, good healthy fruit, and lots of cleanliness and hygene in the winery is important if you work that way. I'm thinking of showing the sulphur content on the back labels of my wines this year (but my jury is still out).

  21. Last night i suffered an anaphalactic reaction to a Pinot Grigio and was rushed to hospital, too much sulpher caused this . so i think yes some sort of indication as to how much should be on the label is very important.