High gravity brewing

[rossbaker]

Hi all, sorry for the slight duplication, as I've also mentioned this in the pressure fermenting thread... This weekend I'll be brewing a 1.140 dopplebock. I've never brewed a beer this big and I have a couple of questions.

1. This will be my first time using an o2 setup. Given the gravity, any tips about how long to pump and at what psi?

2. I'll be building a very big starter of Zurich lager yeast, but also setting some aside to build up incase it stalls and needs an extra feed. What is the best way of adding more yeast? My fv will be a corny keg, batch size will be 15l. Should I rack into a second keg when adding new yeast? Should I also introduce more o2 at this stage, which seems counter intuitive, or keep all o2 out after the initial pitch?

Thanks as always.

 

[manticle]

You can split the wort - add yeast to a half batch, day or two later, oxygenate the fresh, other wort and add to the main. Look up draflaussen.

1.140 is big for a doppelbock, non?

 

[Garfield]

You can split the wort - add yeast to a half batch, day or two later, oxygenate the fresh, other wort and add to the main. Look up draflaussen.

1.140 is big for a doppelbock, non?

It looks like 1.112 is the upper limit historically so he's not much over

 

[rossbaker]

You can split the wort - add yeast to a half batch, day or two later, oxygenate the fresh, other wort and add to the main. Look up draflaussen.

1.140 is big for a doppelbock, non?

I'll look that up, sounds like a good idea Manticle. Yes, this one is a but beyond the style limits. Trying to clone a Samiclaus beer.

Does anyone have some tips regarding the o2 dosage?

 

[wide eyed and legless]

When I did my RIS a couple of years ago I gave the wort 2 doses of oxygen within 24 hours , I believe in the oxygenating thread there is more info. What I tend to think of is, before they had the ability to oxygenate and the brewers of old used to aerate they were still able to produce big beers, probably with big starters in which the yeast had already had a good dose of oxygen from either stirring or shaking.

 

[manticle]

I think big, healthy starters are crucial.

 

[MHB]

It looks like 1.112 is the upper limit historically so he's not much over

Somewhere close to 1.100 give or take (preboil), reason is L:G it takes around 2:1 to cover the malt in the tun with water, efficiency wont be too flash, but any less water and you will have malt that isn't wet, wont be converted and extracted into solution.
Low L:G favours the action of cytolytic enzymes (mostly Protease and Glucanase) so you can expect higher (proportionally) amounts of dissolved protein and glucans, a longer more intensive boil is recommended.

High extract stresses yeast, if you look at the equation for yeast pitches and were targeting around 1 million cells/mL / point of Plato, you need twice as much yeast as for a 1.050(ish) wort. I would like to see more yeast.
For 15L at 1.140, 15,000*28.5*1,000,000 = 4.275*10^11 (4 smack packs) Wyeast website recommends over 18 Million cells/mL or 2.7*10^11 cells (nearly 3 smack packs) For a Lager yeast add at least 50% more.
So yes an hellaciously good starter or better yet a big slab of slurry from a lower OG wort.

Points to bare in mind is that as wort gravity goes up, Oxygen solubility goes down, as a consequence you can expect less yeast reproduction in the wort. Think bigger pitch.
High gravity worts tend to produce more metabolic side issues, fusels, esters... (all of them). Brew cooler and plan for more hangovers, bigger yeast pitches can help to.
Expect higher FG than you would get from just doubling the OG, Above low L:G favors dextrin production, you might think about mashing longer, a couple of degrees cooler and at a lower pH (5.1-5.2) to favor Beta Amylase activity.
Higher OG's reduce the isomerisation of Alpha acids, worth looking at bumping the bittering addition up (or longer boil time)

All sorts of fun
Mark

 

[rossbaker]

Well this brew day turned out to be a bit of a disaster. It was my second brew on a robobrew and I crushed my grain too fine as well as stuffing up the numbers in beersmith (still getting my head around it) and ending up with too much volume.

This really seemed to stuff up the efficiency and after a 2 1/2 he boil, I was a bit short on volume and only got to 1.100 gravity. I'm still scratching my head about the gravity because I know this usually boosts efficiency on biab set-ups.

To top it off, after the beer was cubed, I discovered I had scorched the base. This was probably because of the fine crush. Worse still, when heating up some water for cleaning, the robo tripped my safety switch and won't turn back on. I haven't had a chance to look underneath, but I'm hoping it was the thermal cut-out switch which should be a simple enough fix. Hopefully I haven't killed it!

 

[rossbaker]

So, Samiclaus is busy fermenting. Hopefully the three step starter of Zurich I did was enough to ferment it out but I have some more I can build up if need be. Also dosed it with 4 minutes of o2 to give it a good start.

Another question though... I'm not sure what I should expect the fg to get down to. Any advice on how to calculate this? The og was only 1.106, not as massive as I was hoping.

 

[manticle]

It depends a lot on your yeast and fermentation.

I'm not familiar with zurich but where does it top out abv tolerance wise? The biggest beer I make starts around 1090 but is boosted post fermentation with candy sugar additions to hit around 11%abv. The beer it's emulating finishes at 1008, I can get mine to 1010 but it needs love, care, patience and then age to integrate. No hot booze flavours but lots of patience and I did once need to finish a batch that was at about 1020 after sugar addition by adding an active starter of a different, higher alc tolerating yeast.

You could try a fast ferment test to see what to expect.

 

[rossbaker]

It depends a lot on your yeast and fermentation.

I'm not familiar with zurich but where does it top out abv tolerance wise? The biggest beer I make starts around 1090 but is boosted post fermentation with candy sugar additions to hit around 11%abv. The beer it's emulating finishes at 1008, I can get mine to 1010 but it needs love, care, patience and then age to integrate. No hot booze flavours but lots of patience and I did once need to finish a batch that was at about 1020 after sugar addition by adding an active starter of a different, higher alc tolerating yeast.

You could try a fast ferment test to see what to expect.

Thanks Nantucket. Zurich is a high abv tolerant yeast, and is actually made for the beer I am trying to clone. White labs lists it as 'very high' over 15%. Mine won't get that high because I didn't reach the og I was aiming for. They also say the attenuation is 70-80, but I must confess that I have no idea what that means!

 

[wide eyed and legless]

Attenuation is the percentage of sugar that the yeast will consume during fermentation. Patience from now on, what temp are you fermenting at?

 

[manticle]

Nantucket? I presume autocorrect or do I have a nickname no-one has told me about?

Zurich sounds perfect.

 

[MHB]

Attenuation is the percentage of sugar that the yeast will consume during fermentation. Patience from now on, what temp are you fermenting at?

Sort of, attenuation can be expressed as the Change over the OG, just remember that the 1.000 part of the gravity isn't there its just the density of water, so a 1.050 beer that finished at 1.006 would have an Apparent Attenuation of the change 44 / 50 = 0.88 or as a percent *100 is 88%.
You could use 0.044/0.050 or put it in Plato (oP) 11/12.5=0.88*100 or 88% and get the same answer.
Just don't try 1.044/1.050=0.994 (wrong answer) remember the 1.000 part is nonunitary!
Remember that it is apparent attenuation i.e. what you see, but alcohol is lighter than water and seriously lighter than the sugar that was eaten to make the alcohol, so Real Attenuation (the actual amount of fermentable consumes) is going to be less (0.82). in the example above 88*0.82=72.16%.
The amount of "sugars" consumed can from there be calculated if you have 23L of 1.050 wort, you have 24.5kg of wort
We know the mass of extract as the oP is 12.5% and 12.5% of 24.5 is 3.019kg
We have converted 72.16% of that, so 3.019*0.7216= 2.178Kg, that leaves 840g in solution.

Not trying to be picky (narky...) it is an important distinction and WE&L sounds like he likes to learn.
Mark

 

[rossbaker]

Nantucket? I presume autocorrect or do I have a nickname no-one has told me about?

Zurich sounds perfect.

Sorry manticle, that was autocorrect. PITA, almost did it again as I wrote this.

 

[rossbaker]

Ok guys, so it's been a couple of weeks. Fermentation kicked off well but it now seems to have stalled at about 1056. I pitched at 16deg then lowered to 11deg. There is still a bit of blow off bubbling but it's pretty slow and I know that's not a good indication anyway.

Because the fv is a corny keg, rousing is pretty easy, just take of the blow off gas disconnect and shake.

Should I start building a new starter of Zurich? If so, what do you think is the best way to go about adding it?

1. Just open corny and tip decanted starter in?

2. Build a vitality starter and tip the whole lot in?

3. Decant starter into a new corny and purge with co2 then pressure transfer over?

4. Just raise the temp back up a few degrees?

The og was 1106, so it has fermented out a fair bit already. Will temperature changes or even using g different yeasts make much of a difference it this stage? As this beer is meant to be conditioned for about a year I'm super paranoid about getting o2 in there but I know some o2 will be required for any new yeast to be able to ferment.

Any help much appreciated! Bloody love having this forum to be able to ask these questions.

 

[wide eyed and legless]

Never had that happen, but in saying that have never attempted such a big beer, I have put more yeast in a stuck ferment before without any seemingly ill effects. I would be checking online for answers Ross if nothing comes up here.

 

[manticle]

If it has stalled, you need to pitch an active starter.
Gentle racking can also help.
Measuring with an hydrometer, yes?

 

[wynnum1]

What about using added enzyme in the mash to get a more complete conversion and it may not be stuck but very slow and if stuck could try a wine yeast like Uvaferm 43,

 

[rossbaker]

Thanks for the suggestions guys. Will start by pitching more yeast. Yes I was using a hydrometer.

By pitching an 'active starter' do you mean starter wort and all or still chill and decant?