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Soapy Taste In Wine

TroubleShooting

Carlos Cardoso — Via email asks,
Q

I came across your site while searching for answers about soapy taste in white wine. I have been making white and red wines for a while and I never had this issue. When I went to rack the white wine for the first time I noticed that it still had sugar residue, so I added yeast nutrients, which got the wine going again. Now when I taste the wine a few weeks later I’m getting the soapy taste. The pH is 3.76.

A
Though tough to define as it can smell different to everyone, there is unfortunately no wine lab analysis panel you can run that says, “Yessir, you’ve got an over-abundance of Ivory Soap Flakes on your hands.” However, if you don’t like it in your wine, it’s a problem. Delving into the wine chemistry literature of my UC-Davis days and through more current articles, what I was able to coax out of the woodwork is a group of culprits: fatty acids. I will spare you all the “acetyl-coA anabolism of cytosol etc.” details, but in general know that fatty acids are a product of fermentation, both of Saccharomyces cerevisiae (the “good guys”) as well as other spoilage yeast like Brettanomyces (definitely the bad guys). Under normal, healthy fermentative conditions, S. cerevisiae can produce various fatty acids like butyric acid, propionic acid, and decanoic acid, which have aromatic descriptors like fatty, rancid butter or “soapy”. When fermentation conditions are healthy (more on that later), small amounts of these fatty acids can do good things for the wine, like combine with alcohol and
Response by Alison Crowe.