If you thought the only ingredient in your wine was crushed grapes– you may be in for a surprise. Winemakers love to spin romantic tales about the climate, soil, and tradition behind their wine, but strangely omit the part about fish bladders, egg whites, and clay. Those are just a few of the unexpected wine additives that might come in contact with your glass before you drink it.

Before you rush to the sink to pour your freshly-opened bottle down the drain, you should know that these additives are not present in the wine you drink. Most additives are used in tiny amounts to smooth out minor flaws in a wine before being removed completely. Though in some cases, additives may remain in the wine if the winemaker has significant mistakes to cover up, like poor fruit quality or an all-around bad tasting wine. 

Unlike most food and drink for sale, wineries are not required by law to list ingredients on the bottle. (Though, that doesn’t stop certain non-interventionist winemakers from doing so!) If wines were labeled like potato chips, you might do a double take if you picked up a bottle and saw things like gum arabic, egg whites, acetaldehyde, charcoal, or fumaric acid… which just scrapes the top of the list of the 70 additives approved by US Alcohol Tobacco Tax Bureau.

The Wine World’s Most Common Additives

Adding certain compounds to wine is certainly not a new practice. Winemakers have been using common additives in production for hundreds of years. They fall into six general categories: anti-oxidants, tannins, acidifiers and de-acidifiers, clarifying agents, and stabilizers.

Here are some of the most common wine additives include:


The most known and often misunderstood, sulfur is an antioxidant used to prevent oxidation and kill bacteria and yeasts that would spoil the wine. The use of added sulfites in winemaking dates back 3,000 years to Ancient Greece, and has been used by nearly every winemaking region since. 

A very small portion (around 1%) of the population has severe sulfite allergy which is why producers include the “contains sulfites” message on labels. Despite the low, low sulfite allergy stats, this chemical compound has become the Big Bad Wolf of winemaking. But for most of us, sulfites are not the key contributors behind your post-drinking headache. 


A basic and necessary component in winemaking, yeast converts sugar to alcohol, but different strains of yeast can dramatically impact the flavor of wine. Some winemakers swear by “native” yeasts, basically whatever’s hanging out in the vineyard or in the cellar, while others only use “cultured” yeasts which offer much more predictable results.


Winemakers might add sugar during fermentation in a process known as chaptalization. It’s not designed to make wine sweeter, but rather used to increase alcohol levels. This is more common in areas like Bordeaux and Oregon, where grapes often struggle to fully ripen. In California, Italy, and NZ, however, it’s illegal to add sugar to wine.

Egg whites, Fish Bladders, and Dairy

Egg whites, isinglass (aka dried sturgeon bladders), and milk proteins are a few additives commonly used to clarify wine.

After wine is fermented, it goes through a clarification process known as fining, where a binding agent is introduced to the wine to filter out unwanted properties, such as tannins, proteins, and sediment. Egg whites, isinglass, and milk proteins have traditionally been used to bind to any tiny particles floating around in the wine, and are removed entirely after they drop to the bottom of the barrel. 

So don’t worry, you aren’t drinking fish bladders and eggs in the finished product. Strict vegans will be happy to learn that non-animal additives like clay can be used in the fining process as well.

The one additive winemakers don’t talk about

Regardless of winery size, producers can’t really get around using the sulfur, yeast, enzymes and bacteria to make wine. But there is one polarizing ingredient that shows up way more in two buck chuck. It’s called “Mega Purple.”

It might be illegal to add sugar to wine, but producers can add grapes high in sugar content, like Alicante Bouschet or petite sirah. But when you’re producing a million cases of wine, you might look for cheaper options– and a small dose of super concentrated Mega Purple makes wine sweeter, adds a bit of texture, and covers up flawed flavors.

Mega Purple has become increasingly common in cheaper wines. In an article exploring its use, Dan Berger interviews a Monterey County winery president who admits “Virtually everyone is using it. In just about every wine up to $20 a bottle anyway, but maybe not as much over that.”

There’s nothing unhealthy or inherently wrong with using Mega Purple, especially for large producers who prioritize uniformity over complexity.  But some view the practice as a shortcut to cover up low-quality wine. Most small-scale winemakers take pride in creating expressive and unique wines that reflect the nuances of the region– and adding Mega Purple puts them at risk of making a wine that masks the true character of their wine.

Going too far

Manipulating a wine with something like Mega Purple pales in comparison to what some wineries have been caught doing. In 2004, winemakers at the KWV winery in South Africa decided to add vegetable flavorings to several of their Sauvignon Blancs in an effort to inject the expected aromas of green pepper and grass. It worked, and the wines racked up several awards before the fraud was discovered.

A few years earlier, the Australian winery Kingston Estate was caught exporting wine containing trace amounts of the silver nitrate, a toxic salt. It was added in minute quantities to hide a sulfurous rotten-egg smell in the wine. Several shipments made their way to the United States, but were caught and impounded.

Luckily, these incidents are few and far between.

Non-interventionist leaders

On the opposite end of the spectrum you have producers like Bonny Doon and Ridge who proudly display ingredients on their wine labels. They believe wine should reflect its terroir, and think heavy manipulation takes away from the wine’s authenticity.

“We believe that for anyone attempting to make fine wine, modern additives and invasive processing limit true quality and do not allow the distinctive character of a fine vineyard to determine the character of the wine.”


– Ridge Vineyards

Should we be concerned about wine additives?

You’ll find strong opinions on either side of the debate. Some critics like Alice Feiring proudly voice their support for “natural” wines free of sulfites and other additives, claiming these wines are purer and more eco-friendly. Others dismiss their claims as a radical-chic trend that doesn’t even have a concrete definition of what “natural” means.

There’s a line between minor adjustments and larger scale manipulation. It’s safe to assume less intervention translates to a better reflection of the vineyard, the varietal, and the vintage. But even if you’re swigging a cheap blend of Mega Purple and Merlot, it’s safe to assume your innards won’t rot away. As a consumer walking down the wine aisle it doesn’t hurt to understand the different approaches to winemaking, but ultimately you should let your own taste dictate what you like to drink.