Fermenting Under Pressure

[Bribie G]

Competition season beckons. I've ordered a KK spunding valve and QD and will pimp it as per Grott's suggestion on another thread.

Does anyone have any experience of pressure fermenting in a cornie (with shortened dip tube) ?

I'm looking to do a micro-megaswill style process by fermenting over gravity, transferring to a clean cornie and topping up with deox water, so I end up with a full cornie.

Even using proper lagering etc, my comp lagers have always turned out a wee bit fruity no matter what I do.

 

[bradsbrew]

I have a 23L mytton rod keg that a cut the dip tube down in. I only used the KK spunding valve with it once, cleaning krausen out of it is not much fun. I would suggest using a blow off tube for the first few days. I now have a fermtasorearse for the pressure ferments (and for staring at, whilst it does its thing)

 

[mtb]

I use a Kegmenter, so almost a corny (and doubles as one, if I ever need it).

The 26L capacity alleviates the need for a blowoff tube and I can get my girly arms in there to clean without an issue.

 

[pirateagenda]

has anyone noticed a slowing of fermentation under pressure compared to normal at the same temps.

Last brew took about a week to get to fg, same brew normally takes 4-5 days, this brew i am at 3.5 days and down to 1.028 from 1.05, both US-05 yeast.

The first one I did accidentally let get to 30psi on day 2, so i thought that may have stunted the yeast and it finished a bit higher than expected (1.011 compared to 1.008 last brew), with some slight metallicy/apple flavour that I am guessing is yeast stress related. Current ferment has been sitting at 10PSI from about 36 hours in.

 

[mtb]

My fermentation times haven't increased, granted they haven't decreased either. I cap it at 10PSI though. Could you be underpitching the yeast?

 

[pirateagenda]

I wouldn't think so. 2 packs of us-05's, hydrated in 30C water for 20 mins before pitching, for 40L batch of 1.05 OG, should be plenty of yeast.

 

[mtb]

30C could be a little warm.. Probably not the cause of your problem but I can't imagine it would be good for the yeast.

 

[pirateagenda]

the specs for safale rehydration are 27C +/- 3C, so that should be ok, but thinking into it a little more, maybe i need to wait longer for it to cool closer to the wort temp so it's not shocked when dumped into 19C wort.

I'll try rehydrating cooler next time and waiting longer and see if it kicks off a bit faster.

 

[Jack of all biers]

30C could be a little warm.. Probably not the cause of your problem but I can't imagine it would be good for the yeast.

30C is the lowest you want really. Lallemand and others recommend 30-35C for re-hydration water temp and the newest article attached to AHB http://www.homebrewtalk.com/correctly-rehydrating-dry-yeast.html recommends 35-40C. In another post somewhere recently Lyrebird Cycles (who has researched the matter for wine yeasts) also stated that 40C was the go. Me personally 35C is my happy medium.

 

[mtb]

Well there you have it, learned something new tonight. Cheers gents.

 

[Dan Pratt]

On the yeast hydration part of this thread.

For ages I tried to hydrate my yeast at the recommended temps, that always then required to slowly adjust that yeast to the temp of the wort over several additions of wort to the said hydrated yeast, result is clean fermented beer, kicks off within 12-24hrs, fermented out in 3-4days.

These days simply use water direct from the tap at the temperature its at, which is often within 5c of the wort. Sprinkle yeast on, leave covered for 15mins. Stir and leave covered for another 5mins. Pitch into wort, result is clean fermented beer, kicks of within 12-24hrs, ferments out in 3-4days.

Saves time when trying to get water to the manufactures temp and then stuffing around adding wort to attemperate the yeast to pitching temps.

Simple, efficient and results in great beer.

 

[pirateagenda]

Pratty, maybe thats what has slowed me down, in the past i was hydrating in tap temp water and it was kicking off fast, now since ive been mixing it higher and adding it higher it seems to have slowed the start down. might go back to the simple way!

 

[mr_wibble]

30C could be a little warm.. Probably not the cause of your problem but I can't imagine it would be good for the yeast.

30C is the lowest you want really. Lallemand and others recommend 30-35C for re-hydration water temp and the newest article attached to AHB http://www.homebrewtalk.com/correctly-rehydrating-dry-yeast.html recommends 35-40C. In another post somewhere recently Lyrebird Cycles (who has researched the matter for wine yeasts) also stated that 40C was the go. Me personally 35C is my happy medium.

I agree. I found an article the other day that suggested re-hydrating at much less than 40C resulted in a significant die-off of yeast.

Ah-ha, found it: http://www.hbd.org/hbd/archive/3301.html#3301-4

TL;DR - Rehydrate a packet of yeast in 100ml of water at 40C
Rehydrating at the wrong temperature can kill 60% of your yeastie buddies.
Reduce temperature to within 10C of wort before pitching
Pitch within 1/2 an hour.

 

[Crusty]

For those of you with a couple of pressure ferments under your belt,
what psi did you go with?
I dry hop a few of my beers & I believe you can dry hop under pressure from day 1.
How did you go about this? Results?
Are any of you guys cranking up the pressure towards the end of ferment to naturally carb your beer?
Any standout differences vs just a normal ferment.

 

[Mardoo]

8-10 psi. I am not going for hardcore ester suppression so chose this level. Somewhere I have a paper I'll track down that talks about specific effects of different pressure levels.

I have been dry hopping with 3 or so days left. Haven't tried from the beginning. ******* fantastic results from dry hopping under pressure! Fully recommend it!

Oxygen exclusion from pitch to serve has been my original goal with the pressurised ferments and transfer, and I'm very happy with the results. I'm seeing greater hop presence, greater shelf life, and want to do some side-by-sides to test malt presence.

However, I greatly prefer the results from English character yeasts done under no pressure whatsoever during ferment. IMHO these yeasts do best when allowed to breathe.

I've started with messing with bumping up the pressure towards the end of ferments to achieve carbonation, but don't have a big enough body of observations yet to offer anything concrete.

Standout differences so far:
1. Better hop presence
2. Ester suppression in high-ester yeasts
3. Better shelf life with eliminating as much O2 as possible in the ferment-transfer-serve stream.

All completely anecdotal, but the results do square with what's seen in commercial-brewery studies I've read. I'm very happy I have the option to pressurised ferment if I want.

Next steps include having a go at saisons and weissbiers this way.

 

[Crusty]

8-10 psi. I am not going for hardcore ester suppression so chose this level. Somewhere I have a paper I'll track down that talks about specific effects of different pressure levels.

I have been dry hopping with 3 or so days left. Haven't tried from the beginning. ******* fantastic results from dry hopping under pressure! Fully recommend it!

If you can track down those papers, that would be real handy.

Dry hopping? Just vent the keg, dry hop & put the spundie back on which is still set @8-10psi? Pressure will build again.
After ferment has finished, do you remove the spundie for cold crashing, if you cold crash.

 

[Mardoo]

Yeah, I'll look for them tomorrow. Whacked tonight.

Dry hopping as you said. I've actually been considering going longer dry hopping, perhaps at the start as you suggest, since my ferments don't go much over 5 days before reaching clean-up stage.

I remove the spunding valve as soon as the ferment is finished, then cold crash.

 

[Crusty]

Yeah, I'll look for them tomorrow. Whacked tonight.

Dry hopping as you said. I've actually been considering going longer dry hopping, perhaps at the start as you suggest, since my ferments don't go much over 5 days before reaching clean-up stage.

I remove the spunding valve as soon as the ferment is finished, then cold crash.

I know quite a few of the Yanks dry hop from the start with no ill effects & like you said, the ferments done & dusted relatively quickly.
I'm probably just going to pressure ferment then transfer to another keg & hook up the gas at this early stage. When I've got a few under my belt, I'll get a bit more adventurous & try a natural carbonation. I assume you know the ferment is finished once the gauge drops to 0.

 

[Mardoo]

I'll add I'm not currently re-using yeast except from top crops. Otherwise I might reconsider the cold crashing. I freeze yeast and make a little extra every time I grow up a pitch. I'm totally in the dark about the effect pressurised fermenting has on future yeast generations.

I'm starting to think maybe a mod should move some of the last couple pages to an appropriate pressurised fermenting thread.

 

[pirateagenda]

another yeast / pressure related question.

Is anyone pitching onto a yeast cake after a pressure ferment?

I have a yeast cake from US-05 used to brew a pale ale, still under 20Psi pressure about 1 week old at that has been sitting under 4C, hasn't had any oxygen contact since initial pitch. It was brewed at 10psi then capped with 5 points to go. 1.050 OG down to 1.012 FG. I'll be brewing a 1.073 IIPA. Is this viable?

The original beer was awesome, although I am slightly concerned that the yeast may be stressed from ramping the pressure to 20psi at the end of the first ferment, and is a 1.050 brew to high to reuse?