On the back label of the wine in Chinese, the ingredients and auxiliary materials column will show: grape juice and sulfur dioxide (SO2). On the back of the English label, it will say “contains sulfites”. At this point, consumers may wonder, “Doesn’t this mean that the wine is an all-natural product with no new additives? How can SO2 be added and is it harmful to humans?
1. Must SO2 be added to all wines?
Must sulfur dioxide be added to wine? A: No. Not all wines add SO2. Not all wines add sulfur dioxide. Some wineries are paranoid and do not add anything, but the cost of these wines is very high and the quality is not good. In general, SO2-free wines should be consumed within 6 months as much as possible because they are very difficult to age.
During the aging process, bacteria and other germs multiply rapidly and the wine will soon deteriorate. In general, SO2 is added to most wines due to the multiple effects of SO2.
2. What is the role of SO2 in wine?
(1) Bactericidal: SO2 is a good bacteriocidal agent that can remove bacteria, impurities and some undesirable yeasts to prevent the quality of wine from being damaged and causing food hazards. Before bottling, adding SO2 can prevent secondary fermentation of yeast, improve the stability of wine and store it for a long time.
(2) Fermentation pause: A variety of wines can be made. Wine fermentation is accomplished by yeast, which converts sugar into alcohol. Once the fermentation process begins, the yeast “never stops eating sugar” and the wine becomes “dry”. If the production of “sweet”, “semi-sweet” and “semi-dry” wines requires the killing of yeast and the suspension of wine fermentation, then SO2 has exactly this ability.
(3) Antioxidants: Many phenolic and aromatic substances contained in wine, especially in white wines, are easily oxidized when exposed to oxygen. At this point, antioxidants are needed, and SO2 is a very suitable antioxidant that is cheap and efficient, and does not produce harmful side effects. At the same time, it can avoid oxidation damage, acetaldehyde oxidation taste, white wine oxidation discoloration and other wine diseases.
(4) Clarification: By inhibiting microbial activity, it delays the start of fermentation, which facilitates the sedimentation of suspended solids in the fermentation matrix.
(5) Acidification effect: Increase the acidity of the fermentation matrix by converting the O2 of wine itself into acid and by promoting the dissolution of soluble acids in grapes, inhibiting the activity of lactic acid bacteria and inhibiting malolactic-lactic acid fermentation, thereby increasing acidity.
(6) Increase the content of pigments and phenols: SO2 can promote maceration and improve the dissolution of pigments and phenols.
3. How much SO2 content is safe?
SO2 has many advantages and plays a very important role in wine production. Is it better to use more SO2? Of course not, the SO2 level should be appropriate. If it is too low, it will not kill bacteria and germs, it will not provide a good antioxidant effect and too much can be harmful.
According to the World Health Organization, the maximum daily intake of SO2 per capita is less than 0.7 mg/kg, and for a body weight of 60 kg, the daily SO2 intake should not exceed 42 mg. Under normal circumstances, the SO2 content in wines produced by regular wineries and breweries will not exceed the standard.
4、What are the dangers of excessive SO2?
Excessive SO2 can make wine smell like rotten eggs because it forms H2S, which combines with ethanol to form mercaptan (c2h2sh), which is harmful to health. For some people who are sensitive to SO2, excessive amounts can cause nausea, vomiting, abdominal pain, dizziness, difficulty breathing, and in severe cases, even life-threatening. Excess SO2 can cause wine to ferment under anaerobic conditions, inhibiting the maturation of tannins and phenolics and slowing the maturation of wine.
Some people say that headaches after drinking are caused by high levels of SO2. This is often a false misconception. Drunken headaches are caused by many factors, such as histamine, alcohol, and stress, but not sulfur dioxide or sulfites. Medical studies have not found a direct relationship between sulfur dioxide and sulfites and headaches.
