My understanding is that it is somewhat of an inexact science/art to blend sours and especially to bottle condition them. For the latter, you would need to have a pretty extensive understanding of not only the specific gravity, but the composition of the residual carbs in the finished/blended beer. That being the case, we are likely bottling 15 gallons or so of year-old flanders shortly, not including any blended young beer.

Is the simplest way to ensure a consistent carbonation level to pasteurize the beer then add new sacc yeast with priming sugar? Or would a potassium metabisulfate+potassium carbonate combo work on dropping out all the bugs like it does with yeast in ciders/wine?

  • 1
    I'm not sure I understand why you would bottle this batch any differently than any other year-old batch? I'd add some fresh sach yeast at bottling, just to be safe, and use the normal amount of priming sugar. I doubt after a year that there's any residual sugar left that's going to contribute to the carbonation.
    – Graham
    Apr 9 '14 at 19:07
  • Are you asking about blending a sour beer with a non-sour beer and bottling immediately? Apr 9 '14 at 22:57
  • @ tobias, yes. I am inferring from your question that if I do blend, I should not bottle immediately? Ie wait for the bugs in the older sour to attack the complex carbs in the younger beer? @ Graham, the reason is that there are likely still dissolved wild yeast/bugs in the older beer that would not only attack priming sugar but also the residual dextrins/complex carbs in the young beer and create bottle bombs.
    – Pietro
    Apr 14 '14 at 13:11
  • @Pietro, That's what I'd speculate, but I don't brew sour beers so have no first-hand experience. Apr 15 '14 at 22:19

You should be good with bottling as normal. I prefer mixing the sugar and beer in a bucket to even out the carbonation levels. After a year the brettanomyces has brought the gravity down very low so I wouldn't worry about bottle bombs. Also, if you pasteurize or sulfite the beer you are robbing yourself of the beer developing further complexities. If you are still worried, you can always buy the thicker Belgian Beer bottles. I know Northern Brewer and MoreBeer sell them.

As far as blending, the idea is to get the fresh, intense lactic sourness of a new beer and blend it with the complex barnyard characters of an old beer. The best way to do this is to taste. Sit down with known portions of each beer and figure out which percent you like the most. My suggestion is bottle at least half straight and use the rest to blend with. That way you can have vintages from different years to work with. I don't suggest bottling anything less than a year old sour.


Force carb using a carb cap and PET soda bottle. Step by step:

  1. Find the appropriate blend
  2. Scale your blending "recipe" up or down to meet your bottling needs
  3. Add this blend in a PET soda bottle
  4. Apply carb cap
  5. CO2 purge a couple times (apply little CO2, don't shake, let sit, open cap. repeat)
  6. Force carb by shaking (apply high CO2, shake, let sit, test. repeat)
  7. Gently pour into sanitized beer bottle
  8. Cap immediately

Works well for the lower carbonated sours, but step 7 can be a big pain for highly carbonated sours.

You could reuse a soda bottle, but it would be better to get a fresh, unused one.

  • so you could theoretically just do this in a keg as well and fill with a beer gun/bottling wand and picnic hose?
    – Pietro
    Apr 10 '14 at 11:57
  • Yeah -- would take a lot more of each part of the mixture, though. And since sours tend to change over time, I wouldn't want to do this...
    – notlesh
    Apr 10 '14 at 16:10
  • I think I would prefer to bottle-condition/naturally carb this beer, but if it turns out that force-carbing is the best way to produce a consistent carb level and beer that is still ages well, I will likely force carb it.
    – Pietro
    Apr 15 '14 at 17:58
  • This method is used by a club member for all his competition entries to ensure perfect carbonation. Bottle conditioning is a bit hit and miss in any case, but especially for a blend. You may benefit from bottle aging anyway, so although I know it's more work than priming your keg, you should get more consistent results with this method. northernbrewer.com/shop/the-carbonator.html
    – Wyrmwood
    Apr 16 '14 at 18:26

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