Preventing Return of VA

You should get your microbes under control before removing VA.  You may think that you will deal with the microbes afterwards. Problem is, in some conditions VA will return before you have a chance to deal with it. VA can climb by .1 g/l per hour under favorable conditions.  Admittedly, this doesn't happen often, but we know of no way of predicting.  We cannot guarantee results in the presence of acetic acid producing microbes.

This can be tricky, especially when dealing with a stuck ferment, because you don't want to simply sterile filter it.  A few things to remember:

  • Analyze your microbes.  Knowing your enemy is helpful.
  • If it is a gram positive bacterium, such as Lactobacilli, Oenococci or Pediococci, you can use lysozyme which is very effective at inhibiting these microbes (it does NOT kill them)
  • Lysozyme will not inhibit primary fermentation
  • Lysozyme can inhibit ML, but your lab supplier can help you overcome this with a special strain of lactic acid bacterium
  • SO2 is not effective against most causes of VA at higher pH
  • If the cause is not gram positive, your best choice is to sterile filter
  • Test for ethyl acetate.  It is often undetectable over the acetic acid, until the acetic acid is removed
  • Be aware that lactic acid bacteria can consume tartaric acid, resulting in a progressive lowering of your TA and rise in pH, along with a rise in lactic acid, CO2, and acetic acid. This is more likely at higher initial pH (>3.5)
  • Before and after our treatment, check your pH and SO2 and adjust accordingly and stay on top of them at least monthly
  • Strongly consider sterile filtering after our treatment of the wine
  • Returning to the same barrels, even if properly sterilized (steam and SO2 gas), may result in leaching of acetic acid from the wood into the wine
  • Sterile filtration is the only certain way to prevent return of VA

Let us know if you would like more assistance with getting your wine treated right.

 
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