Brewing a Lager

[MHB]

The amount of CO2 produced during the ferment will make the balloon look tiny.
If you fermented a 23L, 1.050 wort down to 1.010 you would be making around 630L of CO2 (rough fingercount)
Remember O2 is good at pitching, and after that it’s kept out by the evolving CO2 and your airlock.
Mark

 

[raybies]

The amount of CO2 produced during the ferment will make the balloon look tiny.
If you fermented a 23L, 1.050 wort down to 1.010 you would be making around 630L of CO2 (rough fingercount)
Remember O2 is good at pitching, and after that it’s kept out by the evolving CO2 and your airlock.
Mark

Thanks for the info... this now begs the question, why do people say "keep the fermentation headspace as low as possible to avoid oxigen ingress" when this will quickly be displaced by CO2?

 

[MHB]

If you opened a brewing text book, it would recommend 30% headspace in a fermenter, 50% if you were fermenting a wheat beer.
People say lots of things that don’t make a lot of sense to me, I just work on the theory that half the population has a below average IQ.
Mark

 

[yankinoz]

What if your fermenter is only 50% full, I know ideally it should be 80%; would it be better to try and pressurise the fermenter or would the normal CO2 displace the oxigen adequately? I was thinking of inflating a sanitised latex balloon to reduce the head space.

Note MHB's above comment or Look up the old thread where I addressed a 50% headspace. A beer fermenting to 5% abv would produce many times that volume of CO2 even after saturating the beer. Pressure fermenters of course have relief valves set to release at the desired pressure and prevent wild overcarbonation or an exploded fermenter.

 

[raybies]

How does one determine the maximum pressure/temperature ratio for pressure fermenting... a SafLager™ W-34/70?
And what would happen without temp. control? There's no way for me to get the Fermzilla in my fridge, without lying it on it's side, and my garage temp. currently ranges from 7c to 24c.

 

[yankinoz]

Yikes. Sacrificing temperature control in order to pressure ferment is like trading in a Mercedes for a Yugo. Either get some measure of control, ditch the Fermzilla or find an old fridge that fits it.

You can smooth temp variation by insulating or putting the fermenter in a water bath, except that insulation will lead to fast heating during the active phase of fermentation. You'd need a deep tub to hold water and a Fermzilla. (and make damn sure the taps don't admit bacteria)

At present your best bet is to start fermentation as cool as the yeast allows. With that yeast the ideal would be 8--10, but you'd probably need to ptch two packets. If the temp is likely to drop to 7 overnight, pitch and then insulate with old blankets or whatever. Once you see the temp rising or CO2 being produced, which will take a day or two, immediately remove the insulation (if it happens early in your sleep or while at work, you have a problem). Then try the best you can to keep it cool during the active phase. Once the bubbling slows ro a crawl, insulate again.

S-189 would be more forgiving, It can start at 11 or below and the quality holds up fairly well if temps rise. Ross at Craftbrewer/Bacchus has used it in a room set to 19, I've had it go to 15 on an Oktoberfest and liked the results.

 

[raybies]

Yikes. Sacrificing temperature control in order to pressure ferment is like trading in a Mercedes for a Yugo. Either get some measure of control, ditch the Fermzilla or find an old fridge that fits it.

You can smooth temp variation by insulating or putting the fermenter in a water bath, except that insulation will lead to fast heating during the active phase of fermentation. You'd need a deep tub to hold water and a Fermzilla. (and make damn sure the taps don't admit bacteria)

At present your best bet is to start fermentation as cool as the yeast allows. With that yeast the ideal would be 8--10, but you'd probably need to ptch two packets. If the temp is likely to drop to 7 overnight, pitch and then insulate with old blankets or whatever. Once you see the temp rising or CO2 being produced, which will take a day or two, immediately remove the insulation (if it happens early in your sleep or while at work, you have a problem). Then try the best you can to keep it cool during the active phase. Once the bubbling slows ro a crawl, insulate again.

S-189 would be more forgiving, It can start at 11 or below and the quality holds up fairly well if temps rise. Ross at Craftbrewer/Bacchus has used it in a room set to 19, I've had it go to 15 on an Oktoberfest and liked the results.

Thanks.
So how does one determine temp/psi ratio?
I've seen lagers being fermented @ 27c and 28psi, and I'm not sure how one comes to those figures.

 

[yankinoz]

Thanks.
So how does one determine temp/psi ratio?
I've seen lagers being fermented @ 27c and 28psi, and I'm not sure how one comes to those figures.

What for? Temperature affects pressure, but as long as fermentation is producing gas or the temp is rising, the relief valve will keep pressure steady. Once active fermentation slows the pressure will rise and fall slightly with variations in temp. So what? Again, fermentation will produce plenty of CO2.

 

[Half-baked]

So how does one determine temp/psi ratio?
I've seen lagers being fermented @ 27c and 28psi, and I'm not sure how one comes to those figures.

You seem to be assuming there is science behind any of this.
Pressure fermenting is a newish trend, with no empirical data to back it up (at least that I’m aware of).
I haven’t even seen any reliable studies with sensory panels to validate the theory that you can brew a ‘proper’ lager under pressure at ale temps. (Brulosophy doesn’t count in my books.)
You may or may not be able to do it, but until I see some solid evidence, I’m very happy to stick to the traditional approach: low fermentation temps with a BIG pitch of yeast.

 

[raybies]

I was assuming there was some level of reasoning associated with pressure/temp/duration, but evidence does lend itself more to brewer experimention. My issue is temperature control capacity, so wanted some reasoning/logical pointers before experimenting w/ variable temperatures. I can probably get the max/min temp. differential down to about 10c, but spring maybe more challenging. Garage has hit 62c in summer and -1c in winter, and in spring the swings can be 30c... tin roof, concrete floor, full sun exposure, semi desert climate.

I've got control of pressure and time, it's just consistent temp., but maybe the yeast will be like... "fine whatever".

 

[Half-baked]

Like Yankinoz said, if you are faced with a choice between temp control (even with with a cheap fermenter) or pressure fermenting (with a good fermenter), I’d choose temp control every time.

Some styles could be okay without accurate temp control—there are ways to moderate temp fluctuations without a fridge—but if you’re brewing a lager I would say it’s a must.

 

[MHB]

Actually it’s not all that new, pressure fermentation was pretty thoroughly investigated in the late 80's and early 90's.
The numbers were all done by Narziss around 2005, it hasn’t been widely embraced by commercial brewers. Those that have tend to be the makers of the cheapest mass market beers, not the makers of the best lagers.
Echoing a couple of other people Temperature Control is Critical to making good lagers.
Braukaiser has a very good write-up on Fermenting Lagers
Had a look through a couple of books, Kunze give the subject 2 paragraphs. Fix in passing, notes that blind tastings by professional tasting panels give 1st to open fermentation, 2nd to closed 3rd to uni-tank (slight overpressure) fermented beers.
Mark

From Kunze

 

[Hangover68]

Keep scouring gumtree and facebook marketplace, i found an all fridge large bar fridge for free that easily fits my fermetersaurus so i can now temp control and pressure ferment.

 

[yankinoz]

Keep scouring gumtree and facebook marketplace, i found an all fridge large bar fridge for free that easily fits my fermetersaurus so i can now temp control and pressure ferment.

I'll call that a happy ending. Good luck. If you don't like the results, try without the pressure and then lager.

 

[raybies]

Harvesting lager yeast: I collected the below, but not sure how to harvest it. Utube videos show people collecting the clear liquid, but that's beer.

 

[Hangover68]

I'll call that a happy ending. Good luck. If you don't like the results, try without the pressure and then lager.

I've done both ways, can still lager even after pressure fermenting just now i don't need to move the FV.
I also have another temp controlled fridge more suited to standard shaped fermenters and cubes.

 

[yankinoz]

Actually it’s not all that new, pressure fermentation was pretty thoroughly investigated in the late 80's and early 90's.
The numbers were all done by Narziss around 2005, it hasn’t been widely embraced by commercial brewers. Those that have tend to be the makers of the cheapest mass market beers, not the makers of the best lagers.
Echoing a couple of other people Temperature Control is Critical to making good lagers.
Braukaiser has a very good write-up on Fermenting Lagers
Had a look through a couple of books, Kunze give the subject 2 paragraphs. Fix in passing, notes that blind tastings by professional tasting panels give 1st to open fermentation, 2nd to closed 3rd to uni-tank (slight overpressure) fermented beers.
Mark

From Kunze
View attachment 121054

Re the Fix reference, too bad he didn't provide more detail or a link. Presumably the experiment was done on beers made by the same recipe, and I'll guess they used the hops typical of continental lagers.

A possible advantage of pressure brewing might be in lagers made with assertive hops, especially fruity ones, that lose or change character during extended lagering. Brooklyn Lager is a good example of a hoppy lager, and I've heard of US "New England India Pale Lagers," Whether the brewers used pressure or somehow added hop aroma and flavour after lagering, I don't know.

 

[MHB]

To the best of my knowledge Brooklyn Lager is a very conventionally brewed lager; it’s finished with Hallertau Mittlefrüh used late in the kettle or whirlpool. There was a brewery sponsored recipe on BYO's website at one time, worth a read.
Being another brewer who has had highly late/dry hopped beers go to shit way too fast; I have been thinking about why.
I suspect it’s about stabilisation. All chemical reactions happen faster warmer. So I suspect that a lot of highly reactive chemicals (especially in hops) are being transformed (well taking part in chemical reactions) in the kettle where there is little to no Oxygen. If these hop constituents are added to cooler beer I suspect the reactions take place with whatever is available, often Oxygen.
Practicing very effective Low DO brewing will help but I suspect these beers are highly unstable and that they will never have a long shelf life. Oxygen can act as a free radical so remarkably small amounts can do immense harm to flavours. Pressure fermentation won’t help in the slightest, unless it is part of an overall DO reducing brewing process.
Mark

 

[yankinoz]

To the best of my knowledge Brooklyn Lager is a very conventionally brewed lager; it’s finished with Hallertau Mittlefrüh used late in the kettle or whirlpool. There was a brewery sponsored recipe on BYO's website at one time, worth a read.
Being another brewer who has had highly late/dry hopped beers go to shit way too fast; I have been thinking about why.
I suspect it’s about stabilisation. All chemical reactions happen faster warmer. So I suspect that a lot of highly reactive chemicals (especially in hops) are being transformed (well taking part in chemical reactions) in the kettle where there is little to no Oxygen. If these hop constituents are added to cooler beer I suspect the reactions take place with whatever is available, often Oxygen.
Practicing very effective Low DO brewing will help but I suspect these beers are highly unstable and that they will never have a long shelf life. Oxygen can act as a free radical so remarkably small amounts can do immense harm to flavours. Pressure fermentation won’t help in the slightest, unless it is part of an overall DO reducing brewing process.
Mark

My point about pressure fermenting, which I should have made clearer, is that by reducing lagering time it might reduce the loss of hop flavour. Maybe. Of course lagering temps slow reactions, but if one lagers four to six months (I have) the loss is noticeable and well known.

I'll check out the BYO reference. Thanks.

 

[raybies]

I'm thinking of introducing some higher attenuating yeast in to the fermzilla 1 week after starting fermenting w/ 34/70.
What do you folk reckon?
Objective is to attenuate more and add complixity with different yeast.