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What’s Lurking in Your Wine? Fish Bladders, Egg Whites, and Mega Purple

Not all wines are vegan. Here’s why.

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Unlike other beverages, there's no ingredient label on wine bottles. But if there were, consumers would notice that their juice contains more than just grapes. While the wine industry promotes the romance of vineyards, wood barrels, and magic, the truth is that winemaking is challenging. Grapes are affected by rain, heat, wind, and sun every season. And in order to make up for mother nature’s shortfalls, when a vintage doesn’t yield desired results, some wineries rely on science, along with various additives, to correct mistakes — to improve flavors and to provide a better balance of alcohol and tannins. While these ingredients and techniques are well-known among wine professionals, they’re usually a surprise to consumers.

Below, 11 common additives and techniques some winemakers use to improve juice, found everywhere from cheaper bulk wines to high-end bottles. Who does what, and how often? Wine lovers will never know because legally wineries aren't required to divulge such details, and producers aren’t always keen to share their secrets.

1) Mega Purple: This isn’t a metal tribute band — it’s a grape juice concentrate that, added in small amounts, will deepen a wine’s color, which wineries believe consumers associate with quality. Mega Purple also adds a touch of sweetness. If you’re the average drinker, you’ve most likely consumed it without knowing. Technically, the process is only combining one grape product with another, but this is one additive no one likes to admit using.

2) Animal Products: One would assume all wine is vegan, but animal products — like egg whites, milk products, fish bladders, and bovine pancreas — are the most commonly used ingredients in fining and clarifying wine, which removes undesired particles leftover from the winemaking process.

3) Sulfites: This is one of the only ingredients you'll see listed on a wine bottle. Sulfites occur naturally in wine, but winemakers sometimes incorporate additional sulfur dioxide to help stabilize juice and prevent oxidation. For various reasons, these extra sulfites got caught up in organic labelling laws in the United States. Now, bottles labelled Organic Wine will not have the added SO2, while those that do read Made with Organic Grapes.

4) Water: Illegal in most countries, adding water to wine was once a winemaking trick to dilute cheap wine and make more product. Nowadays, many vintners leave their grapes on the vine longer, which results in higher sugar levels, and ultimately higher alcohol in the finished juice. However, winemakers don’t always want high alcohol in a wine, as alcohol affects a wine’s balance, adds more potency, and even impacts a winery's taxes (the more alcohol, the more taxes). Some regions, like California, allow wineries to add water to correct this problem.

5) Reverse Osmosis: Instead of adding water to lower a wine’s alcohol percentage, Reverse Osmosis is a machine filtering process that accomplishes the same goal, reducing a wine’s alcohol level without diluting its flavor.

6) Chaptalization: Winemakers have added sugar to grape must since Roman times, but it was French chemist Jean-Antoine Chaptal who discovered the end result wasn’t sweeter wines — instead, extra sugar enabled yeasts to produce more alcohol. The process is controversial — it caused riots in France in 1907 — and those countries that allow it (France, the United States, and Germany) regulate how much sugar one can add. In other countries (Australia, Argentina, and Italy), chaptalization is illegal.

7) Cultured Yeasts: For fermentation, most wineries forgo ambient yeasts (those naturally present in the vineyard and winery), and add their own cultured yeasts. When a winemaker adds cultured yeasts, he/she can select a specific strain based on the predictable flavors the yeast will impart to the wine. On the other hand, ambient yeast is usually somewhat unpredictable, and while it’s the more natural option, some winemakers think it’s a bit of a gamble. The natural wine movement adheres to wild yeast fermentation, as do many organic and biodynamic wineries. Neither method is wrong per se, but the use of cultured yeasts can be looked at as another ingredient manipulation.

8) Acidification and Deacidification: Acid is one of the most important components of balance in a wine. If a winemaker doesn’t like the amount of acid nature has provided, he/she can manipulate it by adding malic acid and lactic acid, among others, to increase the level, or use calcium carbonate to decrease it.

9) Powdered Tannins: Tannins are another major component of balance in a wine — they provide astringency, bitterness, and that mouth-drying feel. If not enough tannins were naturally extracted from grape skins, seeds, and stems, a winemaker can add more in powdered form.

10) Oak Chips: Oak barrels can be pricey. And while they contribute many desired flavors, like vanilla and spices, many producers take a cheap shortcut by adding oak chips to wine stored in stainless steel tanks instead. The process saves money and takes a lot less time since the chips pack a more powerful punch. But the end result (which includes vanilla flavors and not much else), most agree, is never as effective as the real thing.

11) Micro-Oxygenation: Thanks to the porous nature of wood, wine stored in barrels is slowly exposed to oxygen over time. This contact with air allows the flavor of a wine to develop and its tannins to soften. But, once again, to save on expenses, some winemakers turn to micro-oxygenation, a process that injects tiny amounts of oxygen into a wine during multiple stages of the winemaking process. This mimics the way air would reach the wine over time in a barrel, but speeds up the process and is much less expensive.

Editor: Kat Odell