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What Causes Wine To Turn To Vinegar?

Posted on February 7, 2011 by Ed Kraus There have been 0 comments

Wine VinegarHello,

I'm curious as to when the threat of wine turning to vinegar is over, if ever, and what causes it. Is there an in depth explanation anywhere I can get the science of this?

Thanks Jane


Dear Jane,

Acetic acid is what makes vinegar taste like vinegar. If you had acetic acid in a jar and poured some of it into a fruit drink, it would immediately start to take on the characteristics of vinegar.

Acetic acid is made by a bacteria known as acetobacter. This bacteria is everywhere: in the air, on fruit, on grape presses, etc. When acetobacter gets into your wine it slowly begins to turn the alcohol into acetic acid (vinegar) if left unhindered.

The key takeaway here is: if you control the acetobacter; you control the vinegar.

During a fermentation the wine is relatively safe. The gases from the fermentation help to keep acetobacter fall-out from getting into the wine must. Also, domesticated wine yeast are bred to inhibit bacterial growth, giving them the term killer yeast. It's after the fermentation that caution needs to be taken.

Fortunately for us winemakers, acetobacter can be very easily destroyed before they have a chance to colonize. All it takes is the addition of sulfites in the form of either Campden Tablets, Sodium Metabisulfite or Potassium Metabisulfite. Use any of these in the wine, and the acetobacter will be very easily destroyed.

I would suggest using sulfites 24 hours before adding the wine yeast. Do not use an air-lock or lid on the fermenter during this time. You need the sulfite gases to dissipate into the air, otherwise it will destroy some or all of the yeast when you add it.

I also suggest adding sulfites just before bottling to keep the wine fresh while in the bottle.
Make sure you use a domesticated wine yeast to keep your fermentation clean. And, always sanitize your homemade wine equipment with a sulfite/water solution before using.

Best Wishes,
Customer Service
Ed Kraus is a 3rd generation home brewer/winemaker and has been an owner of E. C. Kraus since 1999. He has been helping individuals make better wine and beer for over 25 years.

This post was posted in Q&A, Wine Making Blog