View Full Version : Regarding degassing

12-12-2015, 10:15 PM
Hi all,
I'm pretty new to meadmaking, and I've not seen a definitive answer to this question, and I've looked far and wide. What I need is a professional opinion on this, as it's been a matter of debate between me and a few friends.
Degassing during fermentation, it's supposed to speed up fermentation and make life easier for the yeast as honey is rather devoid of the nutrients the yeast so richly deserves and desires, which is from what I've been able to gather the reason for the staggered nutrient approach too.

It'd be great to get a professional's opinion on this, to answer this question once and for all, because I rather need to know.


12-12-2015, 11:22 PM
What is the question?

Degassing releases CO2, which is a good thing with respect to maintaining yeast health.

12-13-2015, 01:26 AM
Yea,, your question is not very defined at all. You need to degass so your must doesn't get to toxic for the yeast. Do it aggressively until mid point in your fermentation,,, or when ever you stop feeding your yeast. minimum. I degass every other day until my fermentation has stopped entirely.

12-13-2015, 05:31 AM
Ok, so this phrase "de-gassing" is often used in the wrong way (at the wrong time in the "make" process).

You would agitate the hell out of a must before pitching/adding yeast, so there's some oxygen in the mix. This is to aid yeast colony development.

Then once the ferment is underway, any further agitation is to try and get a bit more air/O2 in for continued development/improvement of the yeast colony.

We generally suggest this is done to the 1/3rd sugar break (one third of the way between start and finish gravity - presuming a finish at 1.000).

The point being that it gives a guide as to when to change from the aerobic stage to anaerobic.

It just happens that the agitation stirs up any particulate matter (yeast cells, unabsorbed nutrient etc) which in turn, allows the CO2 (which is mostly in the form of carbonic acid) to nucleate out in its gaseous form as bubbles.

This "by-product" of agitation helps stabilise the ferment a little, reducing pH swings a little.

So the correct term would be aeration at that point.

Once the ferment has finished, then that is the point where you would de-gas.

What is the point ?

The de-gas helps with clearing, it allows for a consistency of flavour, it prevents foaming excessively when conducting other processes (stabilising, back sweetening, adding secondary fruit and so on).

How you actually de-gas is up to you and the kit you have available...........

12-13-2015, 08:11 AM
Thanks fatbloke, you gave some good insights. The post wasn't exactly a question, it was a request for a professional's opinion on degassing during fermentation and how it should be conducted. Sorry if the post was badly worded, I was very tired and slightly tipsy when it was written. ;)

12-13-2015, 11:25 AM
Fatbloke probably said it better, but in the beginning it's aeration, getting oxygen into the must. Then as the primary kicks in, it's a combination of aeration and degassing, which (a) gets more oxygen in, (b) gets CO2 out, which helps lower acidity and lowers toxicity for the yeast, and (c) rouses the yeast to keep it active. As the primary ferment nears the end, this action should be done so as to minimize oxygenation and maximize CO2 release (e.g agitation as opposed to using a drill and paint mixer). After primary is complete, the only thing you really are accomplishing is releasing CO2, to help speed up clearing and promote stability. Again, doing so in a way to minimize or eliminate altogether the possibility of oxygenation is now critical.