# Diacetyl Rest Question



## Ross (1/4/05)

Guys,

Done the searches & there seems to be conflicting views all over the place...

John Palmers book says wait till primary is all but finished before raising for 24 - 48 hrs, whereas on a recent online forum with Chris White (President of White labs) he says to remove when Gravity is at 1020 & rest for a week at ale temp.
Is there a general consensus of opinion on which way to go?

Also I've read in some posts to reduce temp a couple of degrees a day down to lagering temp & others that indicate it's not required?

Doing my first lager (Doc's Oktoberfest) with 2278 wyeast & wanting to get the best result possible - It's been down eight days, has a nice foamy krausen & currently 1030 - so up todate advice from an experienced lager brewer would be most welcome...


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## Tony M (1/4/05)

Ross,
I have plenty of thoughts on the subject but little hard knowledge. I have made lots of lagers over the last couple of years and I now find myself doing the diacetal rest when the brew is half a dozen points short of finished. In my humble opinion, starting a five day rest a little more than half way thru the brew would diminish the lager characteristics that are being sought, for the fermentation would certainly finish in those five days. giving a brew half done at lager temp and 1/2 at ale temp.


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## warrenlw63 (1/4/05)

Ross,

Because I ferment in glass carboys I'm not overly scientific with my FG readings.

I start a diacetyl rest when the krausen has dropped and the beer looks like it is starting to fall bright. Say about 10 days or so after primary fermentation.

Then I just warm it up to about ale ferment temps (16-18c) for 2-3 days, rack and then slowly drop the temp about 5 degrees a day until I hit lagering temps.

Never had any detectable diacetyl in my finished beers. My gut feeling is you don't have to be strict about when you do it. So long as it's near enough to the end of primary fermentation and the beer's still on the primary yeast you should be OK.

That said if yeast pitching and/or early fermentation temps are high generally no amount of diacetyl rest will absorb the lot.

Warren -


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## Doc (1/4/05)

Ross said:


> Is there a general consensus of opinion on which way to go?


No


Ross said:


> Doing my first lager (Doc's Oktoberfest) with 2278 wyeast & wanting to get the best result possible - It's been down eight days, has a nice foamy krausen & currently 1030 - so up todate advice from an experienced lager brewer would be most welcome...
> [post="52077"][/post]​


Excellent Beer.
On the Oktoberfest (mine) when it hits 1.020 I raise the temp for a diacetyel rest for 48 hours.
Then back to lager fermentation temps for 24 hours, then as long as the SG is right to cold conditioning temps.

Beers,
Doc


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## Asher (1/4/05)

Gday Ross

Your right, there are many differing opinions on how to conduct the perfect ferment..... I'll explain how I do it, but that's not to say its the only way (many ways to skin a cat). I've come up with my methods after reading lots of differing articles too, applying some of their methods and some of my own logic.... :blink: 

A typical lager ferment runs as follows:
- Pitch yeast at around 20deg (also the temp my lager starters are fermented at )
- I let the beer sit at around 18 deg until the very first sign of krausen foam(usually within 12 hours - or the next morning), then cool gradually over the next 12-24 hours to desired fermentation temp - (Yeast are quite happy to be warmed up quickly but don't like being cooled down too quickly)
- When airlock activity is beginning to slow I turn off my fermenting freezer and let temp of fermentor rise naturally for the diacetyl rest. I never add any heat, just let the yeast activity produce its own heat. (temps usually get back up to around 18-20 deg). I usually just go airlock activity and the look of the krausen to decide when its time to do my rest, but I have taken the odd gravity reading here and its around 1.020.
- I leave the beer at this temp until fermentation has ceased (Usually 3-4 days).
- finally I reduce the temp of the primary by a few degrees a day until its around 10 deg, then transfer directly to a keg for cold conditioning....

Not sure if this helps, but may be a starting point for your own method...

Asher for now


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## Ross (1/4/05)

Thanks guys,

Enough ideas there to keep me on the right track... :beer:


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## Dunkel_Boy (1/4/05)

I do exactly what Asher does, except after the diacetyl rest (and once it's hit terminal gravity) I transfer it to secondary (hopefully glass soon!) and _then_ slowly drop it down, and I keep going until it's around 1-2C. Best of luck!

By the way, slowly can either be done with the fridge thermostat set on the coldest and done in steps with your digital temp controller, or done in one step with the digital controller and with the fridge set to midway-warm... but I recommend the first way, until you know how your fridge behaves. You may not even be able to do it, but it makes it easier in the long run.


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## Ross (1/4/05)

DB,

All my brews are controlled digitally by probes in the actual beer to 
+/- half a degree - so temp adjust extremely easy... Also using a commercial freezer, so can drop temps pretty quick when needed - but looks like slow is the preferred method....Thanks..


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## Dunkel_Boy (1/4/05)

Ross,
That sounds bloody accurate.
I was just suggesting that instead of setting the temp a few times, to slowly get the temp down from 18-20 down to 1-2, you can (if you know your fridge) just set it to 1-2 and it will take 48-72 hours to actually get down there... so you can basically walk away and forget about it. I suggest you be careful if you try it though.


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## Ross (1/4/05)

DB,

It would drop in 24 hrs if i set it & walked away - Is this ok or is it better being stepped?... I'm guessing stepped...


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## Dunkel_Boy (1/4/05)

Probably, yes.
I'm actually wondering if lagering is a function of the yeast, or if it's just temperature-dependant. If it depends on yeast, then it's essential to drop the temperature slowly, or in stages, down to 1-2C, as everybody does. But, since fermentation will be over at this stage (ideally, anyway) perhaps it's ok to chill it down quickly... of course it would shock the yeast out of suspension, but maybe that's not a bad thing.


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## Ross (1/4/05)

DB,

that's one of the things that has got me puzzled - If chris white reccomends a week, i guess he's saying to totally complete the ferment at ale temp & therefore dropping quick should be good?? 

bugger this is difficult compared to ale... maybe JP will see this & give a tip...


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## Dunkel_Boy (3/4/05)

Apparently the book Helles in the Classic Beer Styles series says that you need live yeast in suspension for lagering to properly work... it's a function of yeast and temperature.
So everybody can rest in peace knowing that slowly lowering the temp is good for their beer.


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## jjpalmer (3/4/05)

Perhaps JP will see this and....remember that he completely forgot to STOP doing the diacetyl rest last week and ran out to the shed minutes ago to find water on the floor from the defrosted freezer! His socks can attest that the water was still wet and cold too! Bugger!

Well what can I say about diacetyl rests... I get most of my info from Chris since he is a friend of mine.
As I understand it, some yeasts require a diacetyl rest, some yeasts benefit from a diacetyl rest and some don't need one. And, some fermentations require one, some benefit, and some don't need it. ie. the necessity of a diacetyl rest can depend on your yeast and on your fermentation conditions.

I am doing one for this Vienna with WL OktoberfestMarzen yeast, but I have not done them several times in the past and not noticed a need for it. Other yeasts were Bavarian Lager, and Bohemian Lager...

HOW to do it? Well, I agree with DB, I wait until the krausen has started to fall, but still foamy, still bubbling, probably a few points to go, and then let it warm to 17C or so. And then I forget about it for several [email protected]#$%&*! No, I would only do it for 2-3 at the most. You shouldn't have to clean up very much. Obviously if you want a lager charactor you don't want to conduct a large part of the fermentation warm.

Ah, now I remember, Chris advocates starting the batch warm (to get a high repro rate I think, as well as ease of use to customers) and lowering the temp to primary fermetnation temperature, whereas I recommend chilling to fermentation temperature and then pitching so that there is not an initial warm/high diacetyl period in the ferment that the yeast have to clean up later. Now on the other hand, Chris says that diacetyl is not produced for the first 24?? hours or so, so it doesnt matter if you start warmer.... I will have to pin him down on that statement and get some details.... 

Good Brewing Mates,
John


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## Ross (3/4/05)

Asher said:


> - I leave the beer at this temp until fermentation has ceased (Usually 3-4 days).
> - finally I reduce the temp of the primary by a few degrees a day until its around 10 deg, then transfer directly to a keg for cold conditioning....
> 
> Not sure if this helps, but may be a starting point for your own method...
> ...



Asher, Are you carbonating & then cold conditioning? As it appears the lagering needs to be done on the yeast?

JJpalmer,

How long lagering till it can be carbonated & kegged?


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## jgriffin (3/4/05)

jjpalmer said:


> Ah, now I remember, Chris advocates starting the batch warm (to get a high repro rate I think, as well as ease of use to customers) and lowering the temp to primary fermetnation temperature, whereas I recommend chilling to fermentation temperature and then pitching so that there is not an initial warm/high diacetyl period in the ferment that the yeast have to clean up later. Now on the other hand, Chris says that diacetyl is not produced for the first 24?? hours or so, so it doesnt matter if you start warmer.... I will have to pin him down on that statement and get some details....
> 
> Good Brewing Mates,
> John
> [post="52443"][/post]​



See now this is where i get confused a bit. I've been told time and again the most important time to prevent off flavours in Ales is the first 24 hours where high temps cause everything from fruity esters to fuesel alcohols, yet people seem to promote starting lagers high and gradually dropping them?


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## jjpalmer (4/4/05)

jgriffin said:


> jjpalmer said:
> 
> 
> > Ah, now I remember, Chris advocates starting the batch warm (to get a high repro rate I think, as well as ease of use to customers) and lowering the temp to primary fermetnation temperature, whereas I recommend chilling to fermentation temperature and then pitching so that there is not an initial warm/high diacetyl period in the ferment that the yeast have to clean up later. Now on the other hand, Chris says that diacetyl is not produced for the first 24?? hours or so, so it doesnt matter if you start warmer.... I will have to pin him down on that statement and get some details....
> ...



Yes, this is why I don't advocate starting lagers warm and gradually cooling. I think (experts) say to go ahead and start warm because it is easier, and they don't want to complicate things for new lager brewers. They are probably thinking "oh, it won't make that much difference that they will notice..." but I think this is the wrong tactic. 
Now maybe Chris White has some more data for me that will revise this premise, but my experience and that of several of my friends is that great lagers start out cold. 
Newsflash: You don't need to pitch right away! If your sanitation is good you can put your wort in the fridge and chill it overnight to your fermentation temperature before pitching. Dave Logsden of Wyeast gave a presentation on brewery bacteria and yeast which demonstrated that the bacteria don't care if yeast are present or not, they still reproduce very very fast. So, initial sanitation, not immediate pitching is the key to a clean fermentation.
Cheers,
John


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## sluggerdog (4/4/05)

jjpalmer said:


> Newsflash: You don't need to pitch right away! If your sanitation is good you can put your wort in the fridge and chill it overnight to your fermentation temperature before pitching. Dave Logsden of Wyeast gave a presentation on brewery bacteria and yeast which demonstrated that the bacteria don't care if yeast are present or not, they still reproduce very very fast. So, initial sanitation, not immediate pitching is the key to a clean fermentation.
> Cheers,
> John
> [post="52513"][/post]​




I find this extremely interesting and great news for me! There has been a few times I have had a day to brew but my yeast wasn't ready so I had to put it off, this fixes that problem, thanks John.

My current brew seems to have had a little problem, it seems to be stuck, OG was 1048 and todays gravity is 1028 after 14 days at 10C (Wyeast Pilsen Yeast - 2007)

I have to move on with this brew as I have another ready to go into my fridge so I am planning on resting this for 5 days instead of the 2-3 and hopefully in this time it will lower the gravity enough and finish it off before I CC. Does anyone see anything wrong with this? I am kind f afraid that I will loose my lager chrematistics and/or get some off flavours?

Ideally I would rest it now then back into the fridge for another week at 10C but this is just not possible.

Thoughts? Cheers!


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## Asher (4/4/05)

> Asher, Are you carbonating & then cold conditioning? As it appears the lagering needs to be done on the yeast?



I transfer directly from my primary to kegs, then into a fridge (un-gassed) at around 2deg. The kegs then sit there until (or as long as I can wait anyway) they are ready to come on-line... So about a week before I'm going to need them I just plug the gas into them and let them carbonate over a week or so. I'm very careful when moving them to my serving fridge to not rouse any yeast that has settled. and here they sit until their empty..

Asher for now


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## Ross (4/4/05)

thanks Asher, that makes sense.

Do others rack to a secondary for lagering, or do you leave on the primary for this stage? 

i'll be glad to get back to ales - far less confusing...


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## warrenlw63 (4/4/05)

Ross,

I do a similar thing to Asher. Primary ferment, rack to a keg and lager for a month. Then I put the gas on when I'm contemplating consumption.

The kegs I use have about 20mm cut off the bottom of the dip tube to leave the lees behind. I brew 40 litre batches (2 kegs).

What I do after lagering is just gas and drink the first keg. The 2nd keg gets a longer lagering period which makes me concerned about the lees on the bottom of the keg. So I just rack from one keg to a new one with a jumper hose. (two beer disconnects on about 60cm of beer hose).

I just push from one keg to another with the gas, I watch the hose until the keg starts to look like it's going to kick. I then just quickly pull the disconnect from the receiving keg.

You filter your beer Ross so you'd most likely be pretty well-versed with these methods anyway.  

Warren -


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## Ross (4/4/05)

Thanks for all the advice guys - got it all worked out for kegging now.

Just one quick question on the bottling side - When do you bottle? Do you prime just after the diacetyl rest or bring up to temp after a month of lagering? or otherwise...


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## Dunkel_Boy (4/4/05)

Prime after your lagering... another point that yeast should still be working for lagering.
Lagers are ideally kegged though, because there won't be that much yeast after 4-8 weeks of lagering.


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## Ross (4/4/05)

DB, I guessed if you primed/bottled after the rest & then lagered - it would be pretty similar to racking to your keg & lagering??
Just wanting to do a few comp bottles...


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## Dunkel_Boy (4/4/05)

I guess so, but I would imagine your carbonation levels would be inconsistent. You can bottle/prime/carbonate for a week or so, then lager, but then again you won't get the same effect as lagering the entire batch... because you've got 40 bottles instead of one big bottle.
If you must bottle prime, this is probably the way to go.


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## warrenlw63 (4/4/05)

I'd prime, bottle, keep them warm for a week or so to carbonate.

Then if you've got room in your fridge lager the bottles this way. There'd have to be concerns about the amount of viable yeast available after 4+ weeks of cold conditioning. If there's yeast to carbonate the bottles this would have to aid some way in the lagering process. 

As DB stated though. Lends itself more to kegging.

Ross if you've got a CP filler you can fill from the keg. Having a filter, filtered beer would be a pretty awesome presentation for a comp too. Less worries about how the stewards handle your bottles as well.

Warren -


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## Dunkel_Boy (4/4/05)

Warren,
That's right, and you would think that 8 months of lagering there would be nothing left. Strangely, the last two lagers I did, a helles and a pils, were both bottle primed and had both been lagering for 6-8 weeks. Carbonation was perfect on both.


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## warrenlw63 (4/4/05)

Yep, wouldn't doubt that DB. I'd just be stressing a bit if the bottles decided not to.  

Warren


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## Snow (4/4/05)

Ross said:


> Thanks for all the advice guys - got it all worked out for kegging now.
> 
> Just one quick question on the bottling side - When do you bottle? Do you prime just after the diacetyl rest or bring up to temp after a month of lagering? or otherwise...
> [post="52548"][/post]​



Ross,

my experience is that you get better lagering effects if you lager the secondary before you bottle. I did an Oktoberfest last year and did an experiment where I bottled and primed some beer straight after racking to secondary and let that carbonate at room temp before lagering for 2 months in the bottle. The rest of it, I lagered in secondary at 3c for 2 months before bulk priming a bottling. After they had carbonated, I then put 2 of those bottles into the fridge for another 2 months, so they effectively got 4 months of lagering. Well, bottom line is there wasn't that much difference, although the bottled beer that was left at room temp tasted slightly more complex after 4 months, than the extra lagered bottles. 

Cheers - Snow


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## Dunkel_Boy (4/4/05)

Ha ha, exactly right. My ideal setup would be a few kegs and 12 or so bottles, counter-pressure filled. I'm still not sure on how consistent/easy CPFilling is, but it would be handy... and I'm sure the beer would be very clear/clean.


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## pint of lager (4/4/05)

> sluggerdog Today, 07:55 AM
> 
> My current brew seems to have had a little problem, it seems to be stuck, OG was 1048 and todays gravity is 1028 after 14 days at 10C (Wyeast Pilsen Yeast - 2007)
> 
> I have to move on with this brew as I have another ready to go into my fridge so I am planning on resting this for 5 days instead of the 2-3 and hopefully in this time it will lower the gravity enough and finish it off before I CC. Does anyone see anything wrong with this? I am kind f afraid that I will loose my lager chrematistics and/or get some off flavours?



Stuck ferments are the pits. I had a string of lagers that did this a few years ago.

Are you just starting out and using a shiney new refractometer? This will give you readings that appear way too high.

Easiest plan would be to bring it up a few degrees to 12, gently stir to rouse the yeast and see what happens. Maybe your fridge is runnning a bit cooler than you think. Stirring is also good as it releases trapped CO2.

If you think it is a yeast problem, pitch some more yeast, easily done by adding a saflager.

If you think you may have mashed at too high a temp, grab a sachet of dry enzyme from the homebrew shop and add this. 

Lagers need extra care. They need twice the pitching rates that ales do as they multiply at half the rate of ale yeasts. And to keep that crisp clean characteristic, they need fermenting at the right temps as jjpalmer has outlined.

After my string of poor lagers, I looked to yeast health, pitching rates and water chemistry again. Not sure what cured my lagers but they have been fine since.


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## Ross (4/4/05)

warrenlw63 said:


> Ross if you've got a CP filler you can fill from the keg. Having a filter, filtered beer would be a pretty awesome presentation for a comp too. Less worries about how the stewards handle your bottles as well.
> 
> Warren -
> [post="52558"][/post]​



I was of exactly the same mind as I hate bottle priming - but after a chat with a Brisbane judge, he advised me against it - saying that when judging, if they got a beer that was excellent, but not bottle conditioned, they couldn't help but have doubt over its authenticity & would more than likely give a close decision to the bottle conditioned one!!!

Probably should have posted this to a new thread as I'm sure it will evoke some response from judges here??

Infact I will repost the question...


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## sluggerdog (4/4/05)

pint of lager said:


> > sluggerdog Today, 07:55 AM
> >
> > My current brew seems to have had a little problem, it seems to be stuck, OG was 1048 and todays gravity is 1028 after 14 days at 10C (Wyeast Pilsen Yeast - 2007)
> >
> ...



Thanks POL, I'll look into a few different things.

I have it resting now at the lowest temp possible (about 25C) and since I started resting it, I started to get a krasuen again.

Fingers crossed I won't get too many off flavours.


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## SJW (4/4/05)

I pitch my Lager yeast warm and wait 12 hours or so for some action then bring down to Lager ferment temps, around 9 deg C. It will stay there for 10 to 14 days. That when i pull out for rest for 2 days. I might add that there is always krusen after every Lager i have done even after 14 days, then it normally takes 2 to 3 days to finish and just as the Krusen starts to fall in i rack, and then CC @ 0 or 1 degC. I do not doubt JJPALMER (who would) and am sure that some yeasts dont need or benefit from CC but i CC em all just to be sure. Anyway a couple of weeks CC, if nothing else , helps clear the beer quicker anyway.
That my 3 cents worth.


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## Dunkel_Boy (4/4/05)

I think the only thing with yeast not producing diacetyl (or not producing very much, to be more correct) is that if you do a diacetyl rest and it's not necessary, you're probably producing fusels by having the yeast up around room temperature... so perhaps it's a bad idea. Taste it before you rack perhaps?
I know my pilsener had very little, but I did a rest for two or three days anyway. It was using WLP802, and unsurprisingly, that is a low diacetyl yeast.


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## sluggerdog (4/4/05)

Dunkel_Boy said:


> I think the only thing with yeast not producing diacetyl (or not producing very much, to be more correct) is that if you do a diacetyl rest and it's not necessary, you're probably producing fusels by having the yeast up around room temperature... so perhaps it's a bad idea. Taste it before you rack perhaps?
> I know my pilsener had very little, but I did a rest for two or three days anyway. It was using WLP802, and unsurprisingly, that is a low diacetyl yeast.
> [post="52611"][/post]​



The question of which yeasts need the rest and which do not comes to mind.

How do we know?


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## Ross (4/4/05)

sluggerdog said:


> Dunkel_Boy said:
> 
> 
> > I think the only thing with yeast not producing diacetyl (or not producing very much, to be more correct) is that if you do a diacetyl rest and it's not necessary, you're probably producing fusels by having the yeast up around room temperature... so perhaps it's a bad idea. Taste it before you rack perhaps?
> ...



slugger,

some of the wyeast descriptions mention it 

http://www.wyeastlab.com/beprlist.htm#1098


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## Jim - Perth (4/4/05)

I am inclined to go with John Palmer on this one.

I am about to embark upon my annnual lagering now that winter approaches but was only contemplating using packet (S -23) yeast since I'm unlikely to brew more than 3 - 4 lagers & or bocks this winter.

It appears to me that the reason for starting at ale temps & then bringing temp. down to lager temps is to make it easier, particularly for the packet (dry) yeast user, since an 11g sachet requires that 2 sachets be used if pitching at lager temps but only 1 sachet being recommended if pitching at ale temps.

The problem therefore being that the yeast are not present in sufficient numbers if only 1 sachet is used (at lager temps) & fermentation takes awhile to get under way & therefore may not get off to a good strong start.

What I propose doing therefore is to use only one sachet of S - 23 but to pitch it with a starter & then, once it has built up some numbers ie. developed a krausen, I will pitch to the wort at around 8 - 12 deg. C. This way I can avoid the risk of catching the fruity ale flavours & maximise the opportunity to cash in on the crisp lager freshness that comes from the low temps but have sufficient yeast numbers to get the brew underway with a minimum of delay.

Any thoughts on my proposed plan of attack?


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## Dunkel_Boy (4/4/05)

Jim - Perth said:



> What I propose doing therefore is to use only one sachet of S - 23 but to pitch it with a starter & then, once it has built up some numbers ie. developed a krausen, I will pitch to the wort at around 8 - 12 deg. C. This way I can avoid the risk of catching the fruity ale flavours & maximise the opportunity to cash in on the crisp lager freshness that comes from the low temps but have sufficient yeast numbers to get the brew underway with a minimum of delay.
> [post="52628"][/post]​



The cost of a pack of dry yeast is $2-$5, I would just pitch two sachets. Plus, S-23 sucks ass.

Sluggerdog, two ways to find the diacetyl. Either taste when it gets around 1020 (or whatever), and if you are picking up buttery goodness, bump it up to 20C. If not, I wouldn't worry about it.
The other way, the link Ross posted up, and also the information is available on www.whitelabs.com For dry yeasts, I think it's a case of taste it and see.


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## Jim - Perth (4/4/05)

Unfortunately, there is not much choice when it comes to dry lager yeast.

Cheapest S - 23 in Perth is around $4 - Not a huge issue but for the cost of 2 sachets you may as well buy a liquid & pitch the lot.


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