Sulfur dioxide (or other sulfides) has always been a very important food additive, and the sulfur dioxide content in wine is much lower than that of some packaged foods or even preserved fruits. So, what is the significance of the existence of sulfur dioxide in wine?
What is sulfur dioxide?
Sulfur dioxide is the most common and simplest sulfur oxide and is a food additive that is allowed at home and abroad. Nowadays, sulfur dioxide plays a role in color protection, antiseptic, bleaching and antioxidant in the food industry, but there are strict requirements for dosage at home and abroad. That is, the right amount can be allowed.
Sulfur dioxide, wine has to be used, to know why wine contains sulfur dioxide, you need to know how the wine is made.
Now wine is fermented from grape juice. There is a lot of sugar in the grape juice, and during fermentation the yeast converts them into alcohol. Therefore, the more fully fermented, the more complete the transformation, the more alcohol in the final product, and the less sugar.
The amount of sugar left behind determines how "dry" the wine is. For example, "dry red" refers to red wine with a low sugar content, while a high sugar content is called "sweet wine". Different "drynesses" and other trace components, such as tannins, polyphenol compounds, etc., make up a wide range of wines.
1. Sterilization
There are many unnecessary bacteria or fungi present during wine fermentation. These fungi, like yeasts applied by winemakers, have (some unnecessary) effects on the biochemical changes in grape juice.
The addition of sulfur dioxide can reduce this kind of annoyance for winemakers, because sulfur dioxide can inhibit the growth and vitality of many strains, and it is just enough to spare yeast that promotes alcohol fermentation.
2. Prevent oxidation
What forms a "phase killing" relationship with sulfides is oxygen in the air. Grapes or grape juice as a raw material, if completely exposed to the air, are very susceptible to excessive oxidation (not fresh enough, even rotten, etc.). As a result, wines are almost always fermented in a confined environment.
The presence of sulfur dioxide undoubtedly provides a "protective film" for fresh raw materials, which can bind to the raw material components before oxygen, thereby preventing the reaction between the raw material and oxygen. Therefore, almost all wines need sulfur dioxide to protect themselves during the production process, while maintaining a fresh color. It is worth mentioning that even natural wines that advocate no additives must use sulfur dioxide to prevent premature wine decay.
3. Does sulfur dioxide in wine cause harm to the human body?
The World Health Organization stipulates that the amount of sulfur dioxide (specific body weight) inhaled per person per day should be controlled within 0.7mg (/kg), otherwise, the human body will be poisoned. At the same time, if the sulfur dioxide content of the wine is too high, it will also emit a bad smell such as rotten eggs. But not all wines add sulfur dioxide.
Only a small amount of wine in the world does not require the addition of sulfur dioxide. Such wines are generally red wines, because red wines have higher tannins than sweet wines and white wines, and they already have strong antiseptic and antioxidant capabilities.
In general, making wine without adding any sulfur dioxide carries greater risks, higher production costs, and more importantly, quality is not necessarily very good. For most winemakers, this is also too unpredictable, perhaps the whole liquor will be spoiled, or the liquor is extremely unstable and easy to deteriorate. Therefore, wines without sulfur dioxide should be drunk as soon as possible, because it is easy to breed bacteria and cause the entire wine to deteriorate due to continued aging.
In addition, wines without the addition of sulfur dioxide may also have a faint wild game or unusual odor, such as a rat odor. Because there is no sulfur dioxide present, this odor is produced in malic acid-lactic fermentation. Moreover, wines with zero sulfur dioxide may also have serious bottle differences, and even the same batch of wines is difficult to ensure the same taste and quality.
Most wines will add an appropriate amount of sulfur dioxide to maintain the life of the wine, so it is not possible to use sulfur dioxide as a criterion for judging the quality of a wine, and it can only be said that it does not affect the health and taste of the wine.
There is no doubt that "sulfur-free" winemaking is a high-altitude tightrope walk, and even after hundreds of years of development, there is still no better alternative than sulfur dioxide.