Confused about lagering times and temperatures

[DJ_L3ThAL]

Sorry you said 25L, the above example would still be plenty of yeast growth.

 

[Dan Pratt]

Good thread with good info - I hadnt made a lager since batch # 39 and for batch # 90 it was time to try.....

The Lager that I made was a 1.048OG and I made a 1.5lt starter and when that finished, decanted off and added another 1.5lt's to ferment out, how much yeast that was exactly Im not sure. Both were on the stir plate at ~ 18c and when the second step was fermented out I cooled that yeast down to 5c while the Lager wort I made was cooling. I added 90seconds of pure oxygen to the wort, decented starter and pitched the yeast cold and allowed the fridge fans to bring that to 10.5c for fermentation.

I was extremely surprised at how well fermentation went, considering the wort had krausen forming after 15hrs and at day 5 was at 1.015 gravity that was much faster than I had anticipated, I was expecting a 8-10day primary ferment. I turned up the STC heat to 17c for 3days, checked gravity and is at 1.004 and today will commence a slow decrease in temp ~ 3 degrees per day till it gets to 4c and rack for lagering.

Learning/listening to MHB over the years taught me alot so I aimed for certain things like over pitching (in this case it was likely to have still been low), pitching cold and making sure it had plenty of O2 before pitching. The results will not be known until xmas as it will be lagered for 6weeks but I think its on the right track.

 

[rude]

You cant do a 1.5L, remove the top layer and add another 1.5L to the freshly grown yeast population. Youll get minimal growth. Each step needs to INCREASE in size.

E.g. 10mL yeast into 100mL wort. Then resultant yeast into 1L etc. Each step needs to have the balance between amount of yeast and volume of wort known as the inoculation rate to maximise the amount of growth you get whilst not stressing out the yeast.

A good rule of thumb example would be one reasonably fresh white labs vial (50% viable) straight into a 3L starter (on a stir plate) wort for a 23L batch at 1.050. This would be a growth factor of 8.9 and result in 493 billion cells wherr the batch needs 427 according to mr malty.

According to mr malty at 50% 21st of the 8th month viability you would need 2 vials and a 3.8 litre starter
So inoculation rate is 10x MHB uses 6x but said 10x is the step up rate
What is the first step up from a wyeast smack pack in date ?
Been up all night, shift work had better sleep on this food for thought
Thanks DJ will come back to this might have to go to the yeast section & do some reading

 

[DJ_L3ThAL]

Sorry mate your first sentence is confusing me (I'm at work so I'm not surprised)...

Both white labs and wyeast packs are both 100 billion cells at the time of manufacture, every day after this they decrease at a predetermined rate chosen by mr malty. They each have different best before dates (WL being after 4 months and Wyeast after 6 months). Just take 4 months as its conservative.

So 50% viability is assuming your packet is 2 months old. Every time you brew you'll need to ascertain your viability if you want good metrics to work off. I was merely guessing you have 50% viability, check your pack and redo the calculation in mr malty accordingly and you will be on the right track.

 

[MHB]

[SIZE=medium]Couple of catch-up replies[/SIZE]

[SIZE=medium]Yes the wort needs to be aerated, there really is no difference between a starter and a wort, we want exactly the same things to happen in the wort as happen in the starter. Aerating to 10 ppm with O2 and having a healthy wort means that not only does the yeast reproduce but it consumes a bunch of stuff in the wort (proteins, lipids and other fatty acids...) that we want removed (they contribute to staling of the beer and can decrease head) and that the yeast regard as vital nutrients.[/SIZE]
[SIZE=medium]Turns out that at around 10ppm of O2 the yeast will run out of everything at about the same time, before switching over to anaerobic fermentation - result is maximum population of healthy yeast, and minimum amounts of undesirable wort constituents, big win all round.[/SIZE]

[SIZE=medium]Stir Plates? Well I suspect you would be much better off investing in O2, yes stirring helps but I think there is no way you are going to get enough O2 into solution on a stir plate to achieve anything like the assumed rates of reproduction. Likewise with the wort proper, you simply can’t get enough O2 into solution by pouring, splashing, shaking, whisking or even talking harshly. Oxygen or a HEPA filtered air supply really are the best (for me only) choices.[/SIZE]

[SIZE=medium]Putting a fan in the fridge; Well it dramatically improves the rate of cooling of the wort, think about wind chill factor, you feel colder on a windy day than you do on a still day at the same temperature, moving air removes heat faster. Secondly, a fridge can easily be 5oC different between the top and the bottom, where are you measuring the temperature.[/SIZE]
[SIZE=medium]I have seen ferments stall because the yeast at the bottom is so cold it goes dormant (or at least gets very sluggish) while the top is reading 17oC, if the bottom layer is 12oc some ales aren’t going to be too happy.[/SIZE]

[SIZE=medium]Racking/Trub drops; in the Temp/time profile from Kunze, you will see four drops, at least one of them is because they are cropping the yeast for immediate repitching. By choosing the yeast collected between drop 2-3 they have selected for yeast that will keep working right to the end, 0-1 will remove any trub and dead yeast, 1-2 yeast that hasn’t kept working until the beer is fully attenuated, 2-3 the best yeast for repitching and before too much haze trub has had time to sediment.[/SIZE]
[SIZE=medium]As home brewers how often we need to rack/drop will depend on what we want to do with the yeast. If we are cropping to repitch then the process in Kunze would be ideal, if the yeast is going to waste then we could get away with two drops (one being just before packaging) and one at or near terminal gravity.[/SIZE]

[SIZE=medium]Diacetyl rest and warming up; If you pitch enough yeast these won’t be necessary, again referring to Kunze, a Diacetyl rest is a remedial measure to fix a problem caused by under pitching, if you don’t have a Diacetyl problem it isn’t necessary. Similarly with ramping up the temperature at the end, again if the wort has attenuated fully it isn’t necessary.[/SIZE]
[SIZE=medium]Having said all that, it is well worth doing a force test (a small portion of the wort fermented warm, will attenuate the same but do it a lot faster) so you know what the FG is going to be. As we probably won’t be pitching anything like commercial quantities of yeast, it’s a good idea to check for both complete attenuation and the absence of Diacetyl. Which links back to the fan part above, a fan is a heater, it will heat the wort and the fridge just by running, my last fridge had 2 big fans and would reach 40oC if the fridge wasn’t turned on, more than enough heating for a ramp up or Diacetyl rest.[/SIZE]

[SIZE=medium]Lager brewing is one thing guaranteed to bring out my inner nerd. It is a very technical process, quite challenging and for me anyway a lot of fun, it does require preparation and planning.[/SIZE]
[SIZE=medium]If you want to make lager I think it’s best to plan a series of them, start with the lightest one and use your ever growing yeast slab to brew bigger and bigger lagers until you have enough yeast to make a hell big Baltic Porter[/SIZE]

[SIZE=medium]Cheers excuse the ramblings but I do like lager brewing.[/SIZE]
[SIZE=medium]Mark[/SIZE]

 

[TheWiggman]

Many cheers.

Whilst I haven't made rubbish beers so far I do have some differences between other posters. My lagers have taken about 3 weeks to reach FG (though the last few points take a long time at low temps) but I'm 80% there in 2 weeks including a diacetyl rest. Those who get to FG quicker typically either have larger Erlenmeyer flasks than I do or use O2. Haven't heard a single person complain about spending money on an O2 kit.

Might have to put one on the Christmas list. Lord knows I've spent enough cash on this hobby and I do love my lagers. If I could enjoy my lagers even more then money well spent I suppose. Might make my lagering temp process a little simpler too.

About time I reconsidered the way I handle my starters too and might invest in some nutrient.

 

[GalBrew]

My lagers take around 8-10 days to hit terminal gravity. Even pitching cold at 100C and doing the bulk of the ferment at 120C (and a D-rest) the ferment takes off like a rocket when pitching well, giving nutrients, oxygenating etc.

 

[technobabble66]

Apologies if this is a silly question, but:
I'm assume/hoping the lagering phase can be done (entirely) in bottles. Is this correct?

I believe the beer is fully attenuated at the end of the D-rest. So all fermentables should be consumed and CO2 production is finished. Hence I'm hoping it's safe to put into primed bottles.

However, I know the lagering phase allows this special yeast to further clean up various trace compounds in the beer. Would this produce extra CO2?
Do any of the other byproducts of the lagering phase need to be volatized off and hence you should not store the lagering beer in a sealed container?
Does the addition of priming dextrose/sucrose detrimentally affect the lagering phase?

Apologies for being a bit OT, but I'm hoping it's ok as it's relevant to the whole lagering phase thing. :lol:

 

[MHB]

Ideally not done in bottles - sorry
The old name chill proofing tells a story. Lagering gives the haze time to form and precipitate, rack cold then prime. A lot of brewers prime with an ale yeast (I think 514 and S-33 are about the best, but am liking the newish Cask and Bottle from Danstar CBC-1). If you don't rack at the end of lagering the haze will go back into solution - undoing most of the benefits of lagering.
You are very likely to end up with hazy lager
Mark

 

[technobabble66]

Thanks MHB.
That makes sense.

Bugger!!

 

[manticle]

If you consider the products that get dropped out by lagering, you ideally want to be able to leave them behind rather than take them with you to the bottles.

 

[squirt in the turns]

Coming back to the oxygenation question: right now I'm fermenting 40 litres of pilsner that I no-chilled in 2 corneys. Each got a 5 L starter of WY2042. I pressurised each keg with O2 (the cylinder and regulator kit MHB sells), via the liquid post (no air stone), and shook them about, with the pressure at regulator maximum (no idea what this was as the reg does not have a low-side gauge). Interestingly, unlike with CO2, shaking the keg under O2 pressure did not seem to encourage any more gas to dissolve - it bubbled in while I was dialling the pressure up but that was it.

One keg I then emptied into a fermenter via a line connected to the liquid out post, using CO2 to push it once the O2 pressure was not enough - possibly counter-productive as would have led to CO2 absorption? The other keg I left pressurised with O2 for about 8 hours (pitched yeast before adding O2), and it is still fermenting in the keg, with the pressure release valve open. I'm intending to get a spunding valve to try pressurised fermentation, so the wort will be under O2 pressure even longer (until the CO2 from fermentation brings the pressure above whatever the valve is set for).

It will be interesting to see if there is any noticeable difference between the beers produced by these methods.

Stir Plates? Well I suspect you would be much better off investing in O2, yes stirring helps but I think there is no way you are going to get enough O2 into solution on a stir plate to achieve anything like the assumed rates of reproduction. Likewise with the wort proper, you simply can’t get enough O2 into solution by pouring, splashing, shaking, whisking or even talking harshly. Oxygen or a HEPA filtered air supply really are the best (for me only) choices.

Interesting that you say that, Mark. For a starter, would you oxygenate when first made, then put it on stir plate? Or continuously oxygenate (impractical and too expensive, surely)? It occurred to me when I was transferring the pilsner I mentioned above that some of the O2 I got into the wort under pressure would be coming out of solution during the transfer and therefore be wasted. I would have thought that the same thing would happen to a starter hit with O2 at the beginning then put on a stir plate - the agitation would cause the O2 to come out of solution before the yeast had a chance to utilise it.

 

[manticle]

Unless I'm much mistaken, the main (sole) point of a stir plate is to continually oxygenate wort to maximise cell growth. If you have access to pure oxygen, surely you can bypass the stirplate altogether?

 

[squirt in the turns]

Unless I'm much mistaken, the main (sole) point of a stir plate is to continually oxygenate wort to maximise cell growth. If you have access to pure oxygen, surely you can bypass the stirplate altogether?

Well, it also keeps the yeasties in suspension. This seems like it would make sure that they always have access to fresh sugarz, instead of floccing out and sleeping? Maybe this makes no difference, in which case the best approach is to oxygenate it at the start, then leave it be. The other touted advantage of the stir plate is that it drives off CO2, so if you went to the trouble of oxygenating the starter, then put it on a stir plate, would it similarly drive off dissolved oxygen? This is what I was getting at in my post above, where I describe the process of oxygenating under pressure, but then possibly negating the benefits by agitating the wort.

I read the answer to the question "Should I add oxygen to my starter?" in this Mr Malty article as tentatively stating that a stir plate is the best option, even if pure O2 is available.

 

[MHB]

CO2 is much more soluble than is O2 but each gas basically ignores the other, the CO2 wont reduce the amount of O2 and I doubt it will make much difference.
I have left continuous aeration alone, its a sight more complicated and as mentioned can be more expensive to set up, but its not all that dear if you shop smart. The biggest problem is that at too high a concentration Oxygen becomes toxic so you want to know what your doing or you can poison the yeast.

A stir plate stops the yeast lying on the bottom surrounded by other yeast rather than a nice food supply (wort), what I have been discussing is getting your 10ppm of O2 into the wort, getting the yeast in there and letting it brew out, one full lifecycle. Using a stir plate will help this happen a bit faster but I doubt that you will be getting much more Oxygen into the wort unless the flask is open and then there is a very high risk of infection.

If you were setting up a continuous aeration system, I would consider using air rather than Oxygen as you cant get to toxic levels with air, there are foaming issues so a good anti-foam agent might be useful, if using Oxygen you would need a timed on/off solenoid valve and some way to control it, again an anti-foam agent.

I have a couple of yeast propagator flasks (bioreactors) they have stirrers and O2 input, have to get them set up some time - will make getting huge populations easier.
Mark

 

[Black n Tan]

Unless I'm much mistaken, the main (sole) point of a stir plate is to continually oxygenate wort to maximise cell growth. If you have access to pure oxygen, surely you can bypass the stirplate altogether?

A stir plate also allows CO2 to dissipate and CO2 inhibits yeast growth

EDIT: Jamil on MrMalty states the following "You'll get far healthier yeast and far more yeast growth if the yeast have oxygen throughout the process. Adding oxygen at the beginning helps, but the most effective starters provide a continuous source of oxygen...There are several ways to add oxygen: intermittent shaking, a stir plate, pure oxygen, or an air pump with a sterile filter. A stir plate is perhaps the most effective method...A stir plate provides good gas exchange, keeps the yeast in suspension and drives off CO2, all of which increases yeast growth (around 2 to 3 times as much yeast as a non-stirred starter). "

 

[manticle]

All well and good but is yeast that flocs out early in a starter the best cells to be adding to the main wort?
Yeast growth is important but not the only thing you want in a starter. You want to grow as many healthy, performing cells as you can. Presumably with an oxygenation set up you can add oxygen to a starter at any point, decant oxidised beer then feed it wort to get the yeast active again before adding to the main batch.

My yeast starters are far from optimum but from what I've read and what I've tried, I find same wort active starters to perform excellently and my next process improvement will be an o2 setup. Certainly if I was reculturing or stepping up from small splits I think a stirplate would be the way to go but I long ago gave up on that and use fresh packs, top cropping or (very rarely) fresh slurry.
Anyway I'm hypothesising a bit and typing on a phone so I'm happy to be wrong. I just think stir plates are a compromise (like many things) rather than a mecca.

 

[andrewl]

I'm sure Jamil said on one of the BN podcasts that he gives his starters a hit of O2 approximately 24 hours in.
Believes it really boosts the cell growth.

 

[technobabble66]

Not that i have much knowledge nor experience with starters; however, i do have some understanding of biochemistry and cell biology. So ...
It seems like the difference between the O2 injection and stirplate options is that the former would set up the optimal start to the process and the latter would maintain the best ongoing conditions throughout the process.
I don't know enough about what constitutes the best starter result, or rather, what would therefore have the better impact of the numbers and health of the yeast. However, i'd guess the O2 provides the best initial increase in numbers but might taper off in numbers by the end of the starter production, and more importantly the health of the yeast by the end of the starter may be less than ideal as everything sits around stewing in their metabolic wastes. The stir plate OTOH probably doesn't get that initial rocketing of numbers, but provides a much more consistent and stable environment, hence the yeast should be in an overall healthier state by the time they are (decanted and then) pitched, and the numbers should eventually get up to similar level as the O2 option.
This also might better prepare the yeast for pitching into a fresh wort - going from an environment with lots of food and lower wastes levels into one with lots of food and zero wastes. As opposed to the O2 starter which has initially the best conditions but by the end its full of wastes and more resembles the final state of the wort, rather than the nice fresh new one it's getting pitched into.
I'd wonder if that might explain why there are some respected references suggesting if you had to pick one, the stir plate is the way to go - the best overall contribution to both numbers and health of yeast at the time of pitching.

All me just hypothesising. Hopefully not totally incorrect ramblings!
2c

PS: still annoyed i can't lager in bottles. I blame Martin.

 

[DJ_L3ThAL]

PS: still annoyed i can't lager in bottles. I blame Martin.

I knew he had something to do with it!!!