yeast, spunding and pressure

[Zambi]

Okay,
So I got some beer that fermented "normally" then moved to keg, added sugar and put a spunding valve.
All is well, it's carbonating.
But up to about 21 psi.
Would that be because a higher pressure hinders yeast activity?
I would like it to go much higher as the keg (8 ltr oxebar) is outside and 21 psi will only give me around 1.7 volume CO2.
I figure I got 2 options.
1 - move keg to fridge (4-5 °C /39-41 F) and wait and see
2 - move keg to fermentation fridge (as I got space) and again wait & see. According to the tables, 21 psi givesthe right pressure at serving at 13-14 oC (55-57F) but I got a hunch it would be better to use 17-18 oC.(63-64 F)

What you'all think?

 

[HighVoltageMan!]

Yeast under pressure are definitely slower. I pressure ferment a lot and I let the beer take it's time to finish. Spunding works best toward the end of fermentation, so I guess t how far the beer has attenuated. Once I figure the beer has a day or two left, I raise the pressure using the spunding valve as regulator for the amount of carbonation I want, if I guess wrong and it has more sugar then necessary, it gets vented off. If there is not enough sugar it won't hit the proper pressure I was shooting for. It's not unusual to let the pressure build to +25psi @ 58F. The yeast do slow down a bit, but I think if you let it finish and then add some priming sugar, it will go even slower. I would wait.

I had some beers I swear were done, but slowly the pressure built up and eventually the beer hit the target pressure and began to vent. Once it vents, I just keep an eye on it. I use a beer bottle filled with water to vent through. One the beer vents less than 4-6 seconds per burp, it's done. Pretty scientific, but what the hell, it works.

 

[Zambi]

Yeah,
I just got the feeling that somewhere above 25 psi everything slows down dramatically.
My beer is standing at around 82+ F
I'm going to move it tomorrow to 63 or so and occasionally check.
I expect the pressure to drop initially, and then build back up.
We'll see
Just seems a better idea than cooling to 40 F in one go

 

[Craigerrr]

I think that this could be Avery interesting and informative thread. I am new to pressure fermenting and actually have no idea what the best practices are. I have porter fermenting now with S04 (pitched yesterday), and have no idea what I am doing, or why to be honest. I have the spunding valve set at roughly 2-3 PSI, temp at 17C. I was thinking that I would let it go for a few days, then turn it up to 10-12 PSI and increase the temperature to 19-20C. I will be cold crashing it eventually, figured I would either turn it up to 25-30 PSI, or hook up the gas and pressurize before cranking it down to 1C.
Interested in hearing what others may do with S04

 

[Zambi]

For a second I thought you weregoing to carbonate with sulphate
Till I realised you were talking about the yeast.

I think starting of at a very low pressure will work well. It will make the spunding valve act more ir less as an airlock.
After that, it's still experimentation time for me.
I found a calculator that should give an indication on when to increase pressure. I'll post the link later (it's on my computer)

 

[Zambi]

Moved the fermenter
Gonna be interesting to see what happens

 

[Zambi]

So far...
Went from 22 psi @ around 33 oC (92 F)
To 20 psi @ 21 oC (70 F)
But that's less than 24 hours in.

I don't want to go lower in temperature as it's a Voss brew.
I think I will leave it for 5 days, then move to the proper fridge and do a tasting.
I can always up carbonation if needs be.

I also have a 1 litre pet bottle ready. It's moving with the keg.
It will be interesting to compare the two

 

[GFHomebrew]

Honestly straight up I think fermentation under pressure helps to exclude oxygen form your beer through spunding and using the pressure to package under closed system .

Anything else is a bonus but I've found none other than reducing esters produced from a hot fermentation which I believe you @Zambezi Special will love.

Pressure fermentation can be like a new toy at first but after awhile you realise not all beer are ment to be reduced esters .

Enjoy it learn about it then use it to your advantage like controlling hot swings in fermentation temperature.

Remember yeast can stall out under increased osmotic pressure.
In other words don't abuse your yeast with extra pressure doing their job

Sounds like a hard arse boss no

Make sure their pay conditions (yeast nutrients/oxygen)
Are met before undertaking .

Clause :Had alot of beer at the time of writing.

 

[Donoroto]

Pressure fermentation can be like a new toy at first but after awhile you realise not all beer are ment to be reduced esters .

Hefeweitzen for example.

 

[Zambi]

Done 5 days at 20.5 oC (69 F)
Then cooled to 12.5 (55) and next day (yesterday) to 5 oC (41 F).
Will be quite interesting to see how many psi I'll be left with.
It's not really following the graphs due to head space and yeast activity . At least that's what I assume
Plus I got no idea how long it would take for the beer to absorb the CO2.
And of course all will change once I start drinking it