Sulfites are a top allergen triggering strong reactions in people (hives, swelling of throat etc..). Thankfully, studies have shown that few individuals are truly allergic to sulfites (I have read 0.5% of the population but 5% of the asthmatic population) and often sulfite allergies are mistaken with alcohol allergies (the headache you get the next day!). For the other 99.5% of the population sulfites are metabolized and excreted. They are cases of sulfite poisoning in young children but usually no one dies from sulfites present in the food chain (would not recommend eating spoons of sulfites though). So, really asthmatic should avoid food with high levels of sulfites or at least follow the recommendation of the FDA which is to avoid food with more than a 100ppm of sulfites. For the non-asthmatic folks, if you suspect a sulfite allergy (again very low likelihood), you can have yourself tested by an allergist to confirm your suspicion. Foods that are known to contain more than 100ppm of sulfites include dried fruit (excluding raisins), lemon and lime juice, wine, sauerkraut, grape juices, pickled onions for example. Now remember that your sulfite intake is additive, so you should not neglect foods that have less than 100ppm sulfites because they add up especially wine vinegar, maraschino cherries, fresh shrimps, corn syrup, relish, maple syrup, some cookies, many medications etc… The FDA requires that any product with more than 10ppm sulfites be declared on the label.
Sulfites in wine
Sulfites have been used in wines for thousands of year; Egyptians used sulfites starting 2,000 BC! Sulfites are used in wines because they have very interesting properties:
- they are a strong antioxidant protecting the wine from oxygen spoilage
- they are a good anti-bacterial agent (we have plenty of those in wines, few good bacteria and many bad ones)
- they have some decent anti-fungal activities (remember that yeasts that are fermenting wines are a unicellular fungus)
- they do enhance the taste of food, in the same manner than salt
Because of health concerns, governments of many countries have regulated the maximum total amount of sulfites in wines. The maximum limit is 350ppm in the USA, 200ppm in the EU – I think the USA should mirror the EU on that one; 350ppm is a LOT of total sulfites.
The winemaker should not really worry about the level of total sulfites (unless one is getting close to the legal limit) but should focus on the molecular sulfite levels. See, not all sulfites are born alike, and when the sulfite molecule is in suspension in wine, it dissociates itself into several forms that are more or less active chemically. The molecular fraction is by far the most active and the one that the winemaker needs to pay attention to. Several factors should influence the amount of molecular sulfite desired:
- The life expectancy of the wine and its window of consumption (if the wine is to be consumed in two years and for the next 5 years after that, then one should increase the sulfite concentration to help the wine survive)
The expectation for oxygen ingress into the container (cork and bag in the box let more oxygen into the wine vs screwcaps for example requiring increased sulfites at bottling)
- The pH of the wine – very important factor, for a wine with low pH (like in Riesling) the molecular fraction become exponentially more prevalent reducing the need for more sulfites – note that red wines in general have higher pH that whites
- The presence of polyphenols (color, tannins mainly) that are natural anti-oxidant protecting the wine naturally (ie, at same pH levels red wines need less sulfites than white wines)
- The level of filtration, non-filtered wines being more unstable, they might require more sulfites to avoid bacterial spoilage in the bottle
- Barrel aged wines which see more oxygen (vs tank aged) require often more sulfites especially if they are aged for a long time
Overall I would say that wines need to be below 150ppm sulfites. I see very few instances (very sweet wines may be since sulfites benefits are inhibited by sugar) where the level should be higher and I would welcome legislation forcing wineries to put the final sulfite levels in their wines.
Organic, made from organic grapes, biodynamic requirements
The three certifications above all have more stringent sulfites requirement than previously stated. Made from organic grapes and biodynamic wines have an upper limit of 100ppm total sulfites. Organic wines cannot have sulfites added period – one caveat is that yeasts naturally produce sulfites usually around 20ppm, so no sulfite added does not mean no sulfite present. Still organic wines would be a perfectly good way to lower one’s sulfites intake. The only issue I have with organic wines is that they don’t age that well and have to be drunk soon after production which is not always possible.
Sulfites at Pacific Rim
As you might have gathered, I care a lot about sulfite levels. I wish we would not have to use it and still get a great bottle of wine that age and that is good now and for many years. Right now, this is a preservative we have to use to guarantee the freshness of our wines and its stability. I guess I find solace in the fact that at Pacific Rim we rarely (almost never) bottle any wines above 100ppm total Sulfites. Several reasons why we can get away with low levels of sulfites:
- Our wines are often fast turn, they are fresh whites that are meant to be drunk young needing less sulfites
- Riesling has very low pH, allowing us use less sulfites and still have a good amount of precious molecular sulfites
- We stop our fermentations (to make white wines) with a centrifuge which separates yeasts and wine without using sulfites
- We sterile filter our wines
- We use screwcaps – a very tight closure reducing oxygen ingress in the wine
- We make sure our wines go in the bottle with very little dissolved oxygen (we even chase the air between the wine and the wine