Wine is made from a grape juice fermentation, in the process of fermentation of yeast in the grape juice sugar into alcohol, but the process will also generate bacteria, at the same time, the yeast is not grape juice were squeezed out to work, it also has a transitional period, then we have to be concerned about the preservation of grape juice, and the oxidation of wine brewing out later. These are the big problems that test the quality of wine, the slightest mistake will affect the quality of wine, so it is inevitable to find a skill to kill bacteria and keep fresh.

After a long period of trial and error, sulfur dioxidewas found to have all three functions. In fact, the wine itself will produce a small amount of sulfur dioxide in the process of fermentation, but the effect is not big, so the winery will also artificially add sulfur dioxide, in order to protect the natural fruit characteristics of the wine and prevent the wine from aging, also as a protective agent added to the wine, kill the bacteria on the surface of the grape skin.

Although sulfur dioxide has a great effect on wine production, it cannot be neglected that excessive SO2 content will produce the opposite effect, making wine produce a rotten egg smell, which will cause acute poisoning after human consumption, and in severe cases may cause pulmonary edema, suffocation and coma.

As for the negative effect of sulfur dioxide on human body, the World Health Organization stipulates that the maximum amount of SO2 inhaled per person should be controlled at 0.7mg per day based on body weight. Moreover, more importantly, within the time it takes you to shake the glass after opening the bottle, 30-40% of the SO2 in the wine will combine with oxygen and dissipate.

Various countries have also made relevant regulations on the standard amount of sulfur dioxide in wine. The eu limits SO2 to 160mg/l for red wines and 210mg/l for white and rose wines, and allows member states to add no more than 40mg/l in bad years. Generally, the SO2 content of imported high-quality wine is not 160mg/ L. Therefore, a moderate amount of sulfur dioxide in wine is not harmful to humans. It is worth mentioning that trace amounts of SULFUR dioxide are harmless to healthy people, but may have an effect on people with allergies and asthma.