Q: Is diammonium phosphate, which is found in wine, bad for our health? —Marcio Costa, São Paulo, Brazil
A: Diammonium phosphate, also known as DAP, often gets a bad rap. It’s a chemical that some winemakers add to their wines during fermentation, and its non-enological uses include plant fertilization and fire retardation. But it really isn’t as scary as it sounds; in fact, it isn’t scary at all.
What is DAP, you may ask? It’s a nitrogen source for yeast during fermentation—the process by which yeast consumes sugar and converts it into alcohol. Among its several nitrogen sources, yeast likes DAP because it “is kind of the junk food for the yeast,” explains Chris Gerling, enology extension associate at Cornell University. “It’s the easiest for them to break down; it’s the pre-packaged food, versus the food that you have to cook.”
But DAP is not merely a chemical additive: The important thing to remember, Gerling notes, is that DAP “is naturally occurring. You will find it in grape juice, for example, as well as other fruits and vegetables, soy sauce and fish sauce.” Because it ushers along the fermentation process, winemakers can choose whether or not to supplement the naturally-occurring DAP with commercially produced DAP. And either way, their finished product—wine—is sure to have less DAP than the original grape juice, since the yeast will have consumed much of it during fermentation. As Gerling puts it: “You’re consuming less of this in wine than you are in grape juice. So are you afraid of drinking grape juice?”
It’s possible, Gerling concedes, that DAP, like any nitrogen source, could be harmful to the human body in extremely high quantities. But “everything is a poison in the right dose,” he reminds us. “Just like you can have too much of a given vitamin, you can have too much of this too.”
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