overcarbonation

[kootenay kombucha, Nelson, BC, Canada]

Have been dealing with brew overcarbonation for quite some time, several problems in our fermentation methods that have been fixed, flavors are much better now but still dealing with over carbonation in the kegs after 2-4 weeks in the fridge. Not currently carbonating kegs at all, just allowing them to do their thing and then often shaking and releasing pressure in order to bring back down to a serveable level of co2. Have been measuring a starting brix level of about 7, and having the kombucha drop to anywhere from 6-5 over the course of about 14 days of fermentation, but they are still becoming over carbonated in the fridge, and brix is dropping to about 4-4.5 after 4 weeks in the fridge, so definitely still some fermentation happening in the kegs in the fridge. Fridge temp is low enough that fermentation should not be occurring, wondering if there is just still way too much sugar in these batches and if we should try brewing with less sugar to start with. Do not have a brite tank which would help to remove some of the yeast before kegging, but we do reserve the last several inches of the tank where the sediment is. Have been using the method of filling buckets with kombucha and flavoring ingredients 2 days before adding to the fermentor, and then removing scoby and adding flavoring ingredients, it seems like all flavors have over carbonation problem, regardless of how much sugar in fruits is added during secondary ferment. 

Jared I came in to visit a few weeks ago, awesome to see your space, thanks! -Lavinia 

[Jared Englund]

Hi Lavinia,

Sorry to hear about your struggles.  Here are some things I have seen cause over-carbonation:

*Refrigerator too warm.  Anything above 40º is not good.

*Fruit pulp/sediment encourages fermentation and contains oxygen bubbles

*Oxygen - primary fermentation will remove most of the oxygen.  When you transfer the Kombucha, you need to be careful to not introduce oxygen, for example if you pour it from one container to another.  Instead use a slow-moving siphon.  Also when pressurizing kegs, bleed off the oxygen a couple of times.

*Unpasturized fruit - especially fruits that grow near the ground will contain lots of yeast cells

*Tropical/high brix fruits - I have never been able to get pineapple, melon, mango etc. to last in the keg without eventually overcarbonating.

I hope that helps!