Has a wine been enhanced with tannin powder or Mega Purple? There’s no way to know from looking at the label. Here, an explanation of wine additives.

By Megan Krigbaum
Updated May 23, 2017

Has a wine been enhanced with tannin powder or Mega Purple? There’s no way to know from looking at the label. F&W’s Megan Krigbaum reports.

The Truth About Additives
Anyone with the romantic notion that fermented grape juice just magically turns into wine will be astonished by the use of additives in everything from supermarket brands to cult bottlings. Since the earliest days of winemaking, producers have added a little sugar to amp up alcohol and body, employed sulfur dioxide as a preservative and used isinglass (made from fish bladders) to filter out sediment. Today, producers use acids, enzymes and more to correct perceived imbalances or help a wine look or taste more appealing.

What’s Inside That Bottle?
A look at five commonly used wine additives.

Tartaric Acid
When a wine is low in natural acidity (a frequent problem in hot years and warm growing regions), many winemakers will supplement with acid powder.

Mega Purple
Just a little Mega Purple, a superconcentrated substance made from grapes, will turn pale reds into inky ones.

All wines have at least some sulfites—they’re a by-product of fermentation—but most winemakers also add a small amount as a preservative.

Tannin Powder
When red wines are too flabby and need structure, some producers add tannin powder made from grape skins.

Many winemakers buy cultured yeasts for their wines for dependable fermentation; others rely on the natural airborne yeasts that live on grape skins in the vineyards.

A Labeling Tell-All
Even as food-labeling laws become more stringent, winemakers face no legal requirements to reveal the ingredients in each bottle. Paul Draper, winemaker at California’s Ridge Vineyards, thinks that’s a problem. “My hope is that labeling would encourage winemakers to use fewer additives and do less processing, just because they wouldn’t want to have a lengthy list on their label,” he says. Draper unabashedly reveals the ingredients in his wines, from the “hand-harvested, sustainably grown grapes” to the calcium carbonate he had to use when acidity was too high in his Cab—and even the 1.4 percent of water he added to one vintage of Zinfandel that he thought was a touch too ripe.

Wines to Try
These bottles were all produced with minimal winemaker intervention.

Naturally High Acidity
2014 Peter Yealands Sauvignon Blanc ($16).
No acid powders were necessary in making this remarkably vibrant, tropical-scented New Zealand white.

Native Yeast
2012 Selvapiana Chianti Rufina ($17).
This winery, located in a corner of the Chianti region called Rufina, stopped purchasing yeast in 1992. Instead, natural wild yeasts ferment its lively, earthy wines.

Minimal Sulfur
2013 Donkey & Goat Sluice Box ($28).
Jared and Tracey Brandt use a teeny amount of sulfites in their wines. For this ripe and incredibly aromatic white blend from California’s emerging El Dorado region, they added only one-sixteenth the legal limit.