Preservatives often have a negative connotation and are seen as unnecessary artificial additives. Alcohol, acidity, tannins, and sulfites are the preservatives found in wine. Without these ingredients, the wine you love would spoil or no longer be fit for consumption.
Natural Preservatives in Wine
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 increased viscosity, enhancing its body and overall balance.
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 or cause spoilage. 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
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 in contact with the sins. You’ll often hear the term tannins used during a tasting to describe a wine’s structure. Tannins provide the astringent, grippy quality of a wine. They act as an antioxidant and are crucial to the aging process of red wine.
The Role of Sulfur Dioxide in Wine
Sulfites
Seeing “contains sulfites” on a bottle of wine causes uneasiness among some wine drinkers. Sulfur Dioxide, or SO2, can be added during the wine-making process. The purpose of SO2 is to serve as an antioxidant and protect the wine from microbial growth. The absence of oxidation preserves the wine’s pure varietal aroma and flavor characteristics. 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 for 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.
Below is a breakdown of SO2 levels in wine vs food:
- Dry wines: 25-75 ppm
- Sweet wines: 50-300 ppm
- Canned foods: 300-1,000 ppm
- French fries: 2,000 ppm
- Dried fruit: 3,000-10,000 ppm
Naturally-Occurring SO2
While sulfur dioxide is often added in protective winemaking, it is also a natural byproduct of the winemaking process. You may see wine advertised as preservative free but 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 because some level of SO2 is always present after fermentation.
Low-Intervention Winemaking
Many winemakers prefer the term low or minimal intervention winemaking referring to the practice of a hands-off approach in the winery. In our modern world winemakers have many high-tech options available to them to craft any final style of wine they’d like regardless of the qualities of fruit from the current vintage. This type of conventional winemaking can be referred to as toolbox winemaking, utilizing every tool available as a means of intervention. This could include not only the addition of sulfites, but acidification, adding powdered tannin, or even Megapurple (gasp!). In minimal intervention winemaking, you allow nature to take the lead by utilizing indigenous yeast for fermentation, use temperature control to preserve pure varietal flavors, and clarify the wine with sedimentation and racking rather than more invasive forms of clarification.
Minimal intervention is not a regulated and protected certification or designation like biodynamic or organic are. It refers more to a philosophy and approach to winemaking. To understand more of what that term means for some of your favorite wines, it’s important to become familiar with wine producers and their practices.
Wine Style & Price
Producing wines with minimal intervention can be far more time-consuming, and lead to wines that are less consistent year after year, which can be seen as either a pro or a con. Many high-volume producers strive for consistency regardless of vintage, while others prefer to allow for clear expression of the region, grape variety, and vintage. Both perspectives affect the price of the wine with either a more time-consuming process or costs associated with processes that require additional equipment and ingredients. It’s up to the winemaker and the style of wine desired.
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!