Are there adverse effects to adding diammonium phosphate (DAP) as a yeast nutrient in red wine?

Ask Dr Vinny

Hello there! I'm Dr. Vinifera, but you can call me Vinny. Ask me your toughest wine questions, from the fine points of etiquette to the science of winemaking. And don't worry, I'm no wine snob—you can also ask me those "dumb questions" you're too embarrased to ask your wine geek friends! I hope you find my answers educational, empowering and even amusing. And don't forget to check out my most asked questions and my full archives for all my Q&A classics.

Dear Dr. Vinny,

Are there adverse effects to adding DAP as a yeast nutrient in red wine?

—Akbar, Pakistan

Dear Akbar,

For those not already familiar, I’ve written before about DAP (diammonium phosphate), a water-soluble ammonium phosphate salt. As you point out, it’s a yeast nutrient in the context of wine. DAP is also commonly used to support cheese cultures, as a soil additive to increase pH levels in agriculture, to purify sugar and even control dyes in wool.

But in wine, DAP and similar products are used to prevent or fix fermentation problems. Yeast is a very important part of the fermentation process, gobbling up the sugar and converting it into alcohol. But sometimes the yeast tires out before all the desired sugar is converted—that’s what’s referred to as a “stuck” fermentation. Yeasts can be old or weak or just not really digging the grapes they are paired with, or something in the environment can be getting in the way, like the temperature is wrong or something wasn’t clean, disrupting the process. And some yeasts just don’t do well without a lot of nitrogen around, which is what DAP brings to the table.

Some winemakers are against this type of intervention, preferring to make wines more naturally, without any performance-enhancing help. When used properly, not only can DAP help make sure fermentation goes smoothly, it can also prevent unwanted characteristics and even boost flavors and aromatics, but some folks call that cheating.

There are a lot of opinions within the winemaking community about when and how much DAP to add. DAP can increase the risk of volatile acidity, and some believe too hearty of a fermentation can mute aromatics and flavors. There’s also a risk that the fermentation will be too robust, creating microbial instability and paving the path for spoilage organisms.

—Dr. Vinny

Winemaking Techniques Explained Ask Dr. Vinny

More In Dr. Vinny

What does “Winemaker’s Lot” mean on a wine label?

Wine Spectator's expert Dr. Vinny explains how undefined terms are used to sell wine.

Sep 13, 2019

What does it mean if a wine was “cold fermented”?

Wine Spectator's expert Dr. Vinny explains how temperature can impact the results of a wine …

Sep 11, 2019

Can a wine aged using oak chips age as well as a wine aged in actual oak barrels?

Wine Spectator's expert Dr. Vinny explains the pros and cons of oak chips in lieu of oak …

Sep 9, 2019

What does “vin sec” mean on a Riesling wine label?

Wine Spectator's expert Dr. Vinny explains the meaning of "vin sec" and why it's helpful on …

Sep 6, 2019

How does a winemaker stop a fermentation to make an off-dry wine?

Wine Spectator's expert Dr. Vinny explains a few of the methods for stopping a fermentation …

Sep 4, 2019

Is Cabernet Sauvignon a Burgundy wine?

Wine Spectator's expert Dr. Vinny explains how information about different grapes and …

Sep 2, 2019




Restaurant Search

Restaurant Search