Tannins? Egg whites? Sturgeon bladders? Here’s what’s in your wine

It’s not new—winemakers started adding olive oil, sea water, and resins to their product since the founding of Rome.

Winemaking dates back some eight thousand years, when humans were transitioning from hunting and gathering to settling into agricultural communities. That’s three thousand years before the first pyramid was built in Egypt, five thousand before the founding of Rome.

The earliest wines were simply crushed grapes that were allowed to ferment with yeast native in the environment, which sticks to grapes’ waxy coating, according to Wes Hagen, a wine educator who’s studied the history of wine for three decades. Those first wines were consumed within a few weeks to a few months to avoid vinegary flavors. 

There’s a perception that wine has remained one of the most natural beverage products. But in truth, inventive winemakers started trying to find ways to improve the quality and consistency very early, says Michael Reinke, viticulture extension specialist at Michigan State University.

Winemakers started adding sulfites, olive oil, sea water, and various resins around the founding of ancient Rome (753 B.C.) to help preserve wine, Hagen says.

(Ancient wines are having a moment in Italy. Here’s why.)

Wine additives exploded in use in the 1970s and 80s, when “we started using a lot of processes so that people could make more wine more quickly for less money,” says Isabelle Legeron, founder of RAW WINE, a community of low-intervention organic and biodynamic winemakers and enthusiasts.

The Food and Drug Administration currently authorizes the use of dozens of additives in wine making. Michael Kaiser, executive vice president of WineAmerica, says the goal of additives isn’t “to manipulate the product. It’s to enhance it.”

Here’s some of the ingredients you might find in your wine today, and why winemakers use it.

Aging like fine wine

For a wine to sit untouched for years and still be safe to drink, any bacteria must be prevented from multiplying, which would spoil the wine or turn it to vinegar.

Sulfur and its variations (including bisulfite, sulfur dioxide, sulfites, and sulfates) make some of the most effective preservatives. Reinke explains that low doses of sulfur dioxide occur naturally as a product of fermentation, but most winemakers need to add more to create wine that lasts for months or years.

Tartaric, citric, and lactic acids are used to lower the wine’s pH to be too acidic for bacteria or fungal growth. Adding alcohol like brandy to the wine is another option to make the environment inhospitable to bacteria and fungus. “The more alcohol you have, the more stable the wine is,” Reinke says.

Grapes in antiquity were picked early, so they could be harvested before birds or other animals got to them. This resulted in a wine with seven to 12 percent alcohol, Hagen says. Modern vineyards pick grapes when they're sweet and ripe, producing wines 13 to 16 percent alcohol.

Today, some winemakers distill their wine into a brandy and add it back to the base wine, creating “fortified” wine. This yields about 18 percent alcohol—a level that’s less likely to result in fermentation and spoiling.

Making a beautiful wine

When grapes are crushed, the juice produced contains tiny particles of pectins, carbohydrates and proteins, which create a haze or cloudiness in the wine. Roughly half of the FDA-allowed ingredients are used to remove that murkiness and other unappealing cosmetic characteristics.

Bentonite clay, gelatin, egg albumin from egg whites, purified milk proteins called casein and isinglass made from the bladders of sturgeons, are all used to filter the wine through a process called “fining.” These additives attract other particles like magnets, creating larger molecules that are heavy and fall out of the solution or can be filtered out.

(These ancient grapes may be the future of wine.)

Reinke says that some fining additives are more aggressive and can strip components out of the wine that should remain, like color–an obvious issue for red wine. Color stabilizers like gum arabic and acetaldehyde are often used in red wine to preserve color.

Making a tasty wine

Some additives are used to make sure the wine doesn’t taste too bitter. Tannins, part of the cellular structure of the grape, are naturally occurring in wine but can be astringent at high doses—“turning the inside of your mouth into sandpaper,” California winemaker Clark Smith says. “A lot of winemaking is about removing or adding tannins to find the sweet spot.”

Oak chips are also used in cheaper wines to add a toasty, woody character, Hagen says. Wood chips add flavors associated with higher end red wines, Reinke explains: vanilla, tannins, smokiness, and spices. The wood can help with color stability and prevent oxidation of the wine, as well.

Are wine additives safe?

“The most dangerous ingredient in the wine is alcohol, not the additives,” says Joe Zagorski, assistant professor at the Center for Research on Ingredient Safety at Michigan State University.

Additives used in wine are recognized by the FDA as generally safe when used as intended, he adds. Unless people have a specific food allergy, they’re not known to have adverse health effects.

Jeffrey M. Factor, physician and clinical professor of pediatrics at the University of Connecticut School of Medicine, says that allergic reactions to wine are rare but tend to occur more in people with pre-existing asthma. “The [sulfite] levels in wine are certainly high enough to result in reactions,” and can trigger wheezing and shortness of breath. Since most wines have sulfites, Factor recommends avoiding all wines if you know you’re sensitive to sulfites.

There currently are no U.S. labeling requirements for winemakers—unless sulfur dioxide is 10 parts per million or more in the finished product, which legally must be disclosed for the aforementioned consumers who know they’re sensitive to them. But by the end of the year, the European Union will be requiring producers to list the nutritional information and the U.S. could follow suit.

What are natural wines?

Concerns about additives have caused some winemakers to return to the ancient way of making wine, relying only on yeast as an additive. Though so-called “natural” wines have exploded in popularity, there is disagreement of what exactly constitutes “natural.”

“What is ‘natural’ to one is not to another. [Is adding] eggs [to wine] natural? Some say that is not how we made wine thousands of years ago. Others say it is natural because eggs didn’t come from a lab,” Reinke says. “If someone wants to use no additives (beyond yeast), then I would call that ‘minimal intervention.’ But, ‘natural’ to me just says it only contains products that you can find in nature including sulfites, oak, egg whites, cow’s milk, etc. They even used to use ox blood until only a few decades ago.”

Premiere winemakers typically think a lot is sacrificed by avoiding additives, Hagen says. “Many ‘natural wines’ are poorly made and difficult to enjoy with a palate used to modern, clean winemaking.”

Legeron acknowledges natural wines may be cloudier or taste slightly different but maintains that isn’t a health danger. Production can take longer because the fermentation process happens more slowly. And the wine will be different from year to year. But she says the taste is “more authentic,” and is a “more frank representation of that place and vintage.”

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