Preservatives often get a bad rap. Although they are essential to the longevity of food and beverages, they are assumed to be unhealthy chemicals. Alcohol, acidity, tannins, and sulfites are the preservatives found in wine. Without these ingredients, the wine you love would turn to vinegar.


Alcohol and Acidity

The most fundamental preservative in wine is, of course, alcohol. It comes from yeast turning the sugar from grapes into ethanol. It can also be added in a process called fortifying. Wine, in most cases, has an alcohol content of 10-15%. Although the effects of alcohol may be your favorite part about this preservative, it also gives wine its essential body and viscosity.


The acidity also plays an important role. Grapes’ tartaric, malic, and citric acids give wine its notoriously tart flavor. Microbes cannot grow if the pH level is anywhere around 3-4; normally, wine has a pH of 2.5-4.5. The combination of alcohol and acidity prevents the growth of pathogens and microbes that would make wine unsafe to drink. For wines with more sugar and less alcohol, winemakers often have to use an additional process called sterile filtration to ensure the removal of bacteria.



Tannins come from oak barrels and the skins, seeds, and stems of grapes. They are found exclusively in red wines because the grapes are fermented with the skins on. You’ll often here the term tannins used during a tasting to describe a wine’s structure. They act as an antioxidant and are crucial to the aging process of red wine.



Seeing “contains sulfites” on a bottle of wine causes uneasiness amongst some wine drinkers. Sulfites, or SO2, can occur on grapes naturally or be added during the wine making process. Their purpose is to serve as an antioxidant. The oxygen removal prevents microbial growth and preserves the flavor. While high levels of sulfur compounds can give off a rotten egg smell, low levels can give wine the aroma of tropical fruits and minerals.


Although SO2 is toxic in the form of gas, it is safe to consume in food and beverages. It is only unsafe to those who are allergic, which is less than 1% of the population. Higher amounts of sulfites are found in dried fruit, french fries, and bacon than in wine. Eventually, sulfites dissolve as wine ages and could be completely gone by the time you open a vintage bottle.


You may see wine advertised as “Preservative Free” what it really means is that no sulfites were added during the winemaking process. If a wine is truly “Preservative Free,” it is called grape juice. Unless you have certain health restrictions, the preservatives in wine are perfectly safe for consumption and are vital ingredients that make up our favorite drink. So, let go of the stigma and pour yourself a glass!