Fermented but not very acidic - tastes different to previous batches

[stout12]

The short:

Everything was going very well but now the latest batch tastes different. Fermented but not very acidic. Weaker more watery taste, possibly slight alcohol taste?


The long:

I was about to start my 8th batch of Kombucha (1 week primary ferment each) and tasted a sample from the vessel. It tastes very different this time. It has fermented out the sugar (I can’t taste any residual sugars) and has effervescence but not much acidity. In previous batches it was quite tart and had an apple cider like taste. This tasted weaker, more watery, less acidic, possibly slight alcohol taste. The previous batch was also slightly different but not so much to raise questions. Prior to that everything was consistently good and strong. I’m going by taste and have not taken any PH measurements - I should probably get some in the future.

All the ferments have been very active. Bubbles within hours of starting a batch and a constant stream of bubbles the next morning and throughout the ferment. I have been doing small batches and was planning on moving to a larger batch this time but am reluctant to make changes when it tastes so different and I’m unsure what is happening. I have a few theories but really not sure!


* Hot summer temperatures potentially causing yeast to become dominant and reducing bacteria’s ability to acidify. (Located in Australia, Sydney area) Not sure why this would cause a sudden change when it has been hot throughout all previous batches and the taste was strong and tart prior.

* Brewed tea in hot water and then added sugar after (normally I brew tea in hot sugar water). I presumed doing this would mean the tea would steep more efficiently. Not sure why this should be a problem, in fact I would have thought if it made a stronger tea the Kombucha would be quite happy. This is the only difference in my method through all the batches.

* Something else?


Recipe:

My recipe and method is exactly the same for every batch with the exception above (batch 6 & 7 I steeped tea in boiled water then added sugar after steeping instead of steeping the tea in boiled water with sugar.)


Ingredients:

* 1.5L filtered water

* 4 tsp organic loose leaf black tea

* 1/2 cup organic cane sugar

* 1 cup starter liquid from previous batch


Method:

* Boil 750ml water and steep tea

* Cool sweet tea to room temperature over many hours / full day

* Bottle previous batch and mix all the liquid and sediment reserving 1 cup for next batch plus pellicle.

* Add 750ml cooled sweet tea and extra 750ml filter water (total 1.5L) & mix it.

* Cover with cloth and ferment for week in cupboard.



Everything was going so well and so smoothly. The kombucha was tasting great and the fizz was amazing! I was just waiting for my large glass vessel and spigot which has now arrived. For my next batch (#8) I was eagerly looking forward to start making the larger batches but now I’m not sure what to do. I was going to double the recipe (including starter liquid) and then increase the batch size again in the following batches.

What should I do? Anyone have any ideas what is going on? Should I just bottle it and try another small batch or jump in and make the double recipe?

Any help or suggestions welcome. I have my next batch of tea cooling so hopefully I will have some replies soon!

Many many thanks!

 

[RPh_Guy]

The bacteria responsible for most the acetic acid need time, oxygen, and warmth.

A week may not be long enough. Consider leaving it longer to ferment. Try 2-3 weeks and see if it improves to your taste.

What temperature is the fermentation?

 

[stout12]

The bacteria responsible for most the acetic acid need time, oxygen, and warmth.

A week may not be long enough. Consider leaving it longer to ferment. Try 2-3 weeks and see if it improves to your taste.

What temperature is the fermentation?

Thanks for the reply.

The ferment has been very active with a constant stream of bubbles by the next morning after starting each new batch. After a 7 day ferment it has tasted fermented with tart apple cider taste and not sweet. This has been the case with all the previous batches until the latest batch (batch #7) which tastes fermented and is not sweet but it is also not tart or acidic. The temperatures haven’t really changed and we are having consistently hot weather.

It is summer here with hot temperatures around 30c - 40c (86-104f).

In the meantime I started a new (larger) batch and reserved the starter liquid from the top to favour bacteria over yeast. My guess is maybe the yeast became a bit dominant in the last batch especially with the hot weather, but I don’t really know. It has been visibly active as usual and the pellicle is growing well.

I will see how it turns out when I taste it tomorrow and hopefully bottle it if it tastes ready. I will let you know how it goes.

 

[stout12]

An update and good news!

After reserving the starter liquid from the top of the vessel only and not stirring up the yeast & sediment the next batch tastes great again. Back to the normal clean, tart, apple cider taste.

I tried a bottle of the problematic batch which was flavoured with raspberries and absolutely all sweetness was fermented out but it had no tart or acid taste. It tasted alcoholic and unpleasant but the latest batch I just bottled today is tasting great again!

So glad that the problem has been resolved and hope that it won’t occur again. I strongly suspect the yeast became dominant and overpowered the bacteria. Hopefully this will also be a lesson to any new brewers lurking here... reserve your starter liquid from the top (without stirring up the sediment) to favour the bacteria over the yeast.