Fermentation problem

[Nik Saunders]

Hello, 

I have a small problem with fermentation in two of our fermenters.

This year two of our 30 litre speidel fermenters seem to be "sucking" air back in rather than pushing air out or the airlock. 

We've had this before and don't know why it happens or what is the best way forward.

Can anyone enlighten me why this happens and how to get the fermentation going the right way?

For information, we press into a 60 litre barrel then divide it into two so pretty much it's the same juice in each 30 litre barrel. The SG is around 1.065 and the pH was 3.4 measured with a meter not litmus paper. The two fermenters were treated with the same amount of metabisulphate (as per Andrew Lea's book) 24 hours before pitching in the yeast. One had EC1118 and the other had 71B yeast added.  

We added the yeast last Sunday evening.

Thanks in advance,

Nik.

[Bartek Knapek]

I had similar observations at keeving. Some batches, not all, underwent a phase where they were sucking plenty of air, before yeast kicked-in. The temperature was constant, so it had something to do with yeast development, or some oxidation... But they started to ferment eventally. 

//Bartek

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[Nik Saunders]

Thanks Bartek. 

I was worried that air getting in might be a spoiler, but if I lift the lid to re-pitch then more air will get in, catch 22. But I'll be a bit more patient then.

Nik.

[Claude Jolicoeur]

You don't need to worry about air when the fermentation is just beginning. 

You need to worry only at the end when there is no more yeast activity. This is the time when spoliage may occur.

[Cory Widmayer]

I see this happen more frequently with spontaneous fermentation.  Certain yeasts can be crab-tree negative (high sugar concentrations don't induce ethanol fermentation in the presence of oxygen, like with S. cerevisiae), and some bacteria can use oxygen without gas consumption.  This can result in oxygen being depleted without a high production of CO2, pulling a vacuum.

Another possibility is that CO2 is being entrained in the must while oxygen in the headspace is getting depleted (can happen with top-fermenting strains).  This happens more in well-clarified must at lower temperatures, as CO2 can get entrained more easily.

Both of these things will usually only last for a short period at the start of fermentation.

To view this discussion, visit https://groups.google.com/d/msgid/cider-workshop/a7c0d486-7c2e-40c5-9b1c-7f7ce65e40fcn%40googlegroups.com.

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Cory Widmayer