Open Fermentation and/or Different Fermenter Geometry.

Shop deals on ebay
Advertise with us
shop deals on amazon
The Homebrew Forum

Help Support The Homebrew Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
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?
 
DuncR said:
Also… if pressure kills yeast, how does pressure fermentation work?
Click to expand...
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
 
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.
 
Open fermenter has taken off properly now (blue line) :-

Open.jpg


IMG_7647.jpg
 
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 aheadbutt ). 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...

Open2.jpg
 
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.
 
Sadfield said:
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.
Click to expand...

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.
 
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.
 
RoomWithABrew said:
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.
Click to expand...

Doubt away but it was clearer, a lot, like the difference between an IPA and a hazy IPA. Made me wonder if there was something wrong with the closed one. I'll see if I can get a photo later.

The closed ferment was below not above. See picture from Saturday morning above, the open ferment it at the top.
 
RoomWithABrew said:
my apologies re the positioning. I'm in NZ so must have been an upside down memory!

Cooler beer will encourage the drop of yeast a bit quicker though.
Click to expand...

No worries 😂.

It’s an interesting project, a lot riding on the taste test. If it turns out nice I might get a bigger gastronorm. I like the way it slides into the fridge shelf slots.
 
Twostage said:
No worries 😂.

It’s an interesting project, a lot riding on the taste test. If it turns out nice I might get a bigger gastronorm. I like the way it slides into the fridge shelf slots.
Click to expand...
Out of interest, what's the width of your fridge and the gastronorm? Wondering if it would work in mine... 🤔
 
Stainless steel sinks come in many sizes and might work, they have a handy hole in the bottom that could be used with butterfly valve to drop / harvest yeast.
We might be creating an environment with a much greater surface to volume ratio than the famous open fermenters used commercially.
But I'm not exactly sure of the dimensions of say the Harveys fermenters.
 
Not sure how the statement " fermenters have a shallower height to diameter ratio, which is 1:1. "

Would think this means that the height is equal to the diameter, ie 1 foot deep has a 1x1 surface. But the statement isn't clear to me.
 
RoomWithABrew said:
" fermenters have a shallower height to diameter ratio, which is 1:1. "
Click to expand...

Square ones won't. 😉

The ones at Harvey's look to be about 1.5m deep and Φ3m. Brasserie Dupont have a wort depth of 1m. Anything with a wort height lower than the vessel width, the lower the less pressure. As can be seen in this Sierra Neveda clip, some aren't very deep. Approximately, a 1:5 height to diameter ratio, if you adjust from square to round.

 
Last edited:

Latest posts

Back
Top