Open Fermentation and/or Different Fermenter Geometry.

[DuncR]

Found this thread fascinating.
However I’m now even more confused than normal. I have been going through a one person argument for several months as to whether to buy an overpriced shinny fermenter with full glycol chilling setup allowing closed transfer etc. As everyone knows, slightest hint of oxygen after the first few days of fermentation and beer might as well end up down the drain.
Not worried for my top fermenting ales but rather more concerned for lagers which will sit in the fermentation fridge for weeks (or months).
Reading the above, should I save my money and stick with my plastic bucket approach?

Also… if pressure kills yeast, how does pressure fermentation work?

 

[Sadfield]

Also… if pressure kills yeast, how does pressure fermentation work?

Pressure doesn't kill yeast.

Pressure increases CO2 in solution. CO2 in solution changes the way yeast function. Manly, it limits growth and therefore ester production.

"Our yeast contributes to 50% of the final flavour of our beer, which highlights how important it is that we keep our unique strain"

Above is a quote from Harvey's Brewery website, highlighting why one might not want to inhibit ester formation.

There's more information on pressure and esters in this piece.

https://wildflowerbeer.com/blogs/blog/process-e1-primary-fermentation-geometry

 

[Twostage]

I've

Can’t you take the tube out or seal round it with clingfilm?

I've put cling film on it. Why does cling film want to stick everything (including me) but not the thing your trying to get it to cling to ?

 

[Twostage]

We have fermentation. I was initially concerned that the temperature of the wort in the gastronorm (love that word) wasn't climbing as fast as the pot then I realised that it has a greater surface area and no insulation (until it has a good krausen) so heat can escape easily. This might be a factor affecting the flavour profile as it will ferment cooler.

I'm thinking ahead to the transfer to the secondary. Technically the closed pot doesn't need it but as it could be a flavour affecting activity I'm going to do it anyway. Probably either later on on Sunday or Monday.

 

[Twostage]

Open fermenter has taken off properly now (blue line) :-

 

[Twostage]

Decanted them both as they had finished according to temperature profile and the fact that krausen had gone on most (forgot to take a picture ). Upped the temperature to 18.5 to encourage D-rest.

Immediate difference was that the open fermenter's beer was a LOT clearer, maybe because there was a greater area for the crud to settle out ?

Tasted and took a gravity from the closed fermenter (I didn't do a good job of syphoning and ended up with about a litre left so there was plenty to go at). Gravity was 1.009 and the taste was very nice.

One thing that surprised me was the fermentation temperature profiles were exactly the same time wise even though the closed one was 'hotter'. I was thinking that the closed one would have more heat in it therefore it would go faster but it wasn't the case. Nowhere near that point yet but there must be a taste difference between them from the heat dissipation.

Temperature charts...

 

[Sadfield]

I don't really want to coment too much on this, so as not to influence your tasting, but it is very interesting. I no longer use temperature control, and don't miss it.

 

[Twostage]

I don't really want to coment too much on this, so as not to influence your tasting, but it is very interesting. I no longer use temperature control, and don't miss it.

Can’t wait to taste. At some point you need to pm me with your address as you are on the tasting panel. They will be supplied as sample A and B.

 

[RoomWithABrew]

I doubt the open ferment would have been any clearer if you had taken a sample to check clarity from the top of the closed ferment.
Yeast floccs out via gravity, temp profile difference could also be related to the fact the closed ferment was higher in your ferment chamber. Plus sitting above the open ferment which generates heat.
Standing by for differences.