# Dry yeast less tolerant of temperature swings/heating?



## Adr_0 (9/8/17)

Of the last perhaps 6-7 beers I've made, two have had reasonable chunks of acetaldehyde and looking back, both needed a lamp in the freezer and potentially had some temperature swings (bouncing between the lamp and freezer). One was the MJ's saison and this latest has been M44. 

The saison was tasting awesome until I put the lamp in, and the M44 had a temperature dive then had a bit of up and down - basically between 15 and 18°C at times. Lots of acetaldehyde. 

By comparison, liquid yeasts have at times had some temperature bounce and/or heating from the lamp and have been clean as a whistle. 

I have rehydrated properly for both dried yeasts. Could I be overestimating the viable yeast and the temperature/heat is causing too much stress?


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## ein stein (9/8/17)

why is your temp swinging so wildly?
im using an incandescent bulb as my heat source but i painted it with black stove paint and let it cure by leaving it on for a day (lots of fumes came off it) and i only get temp variations of 0.3c which is the minimum i can set my stc to. ive only been using dry yeast but have never had major issues with acetaldehyde.


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## Dae Tripper (10/8/17)

Stright from the BJCP website (lol BJ)
*Characteristic* *Possible Solutions
Acetaldehyde*fresh cut green apples Make sure fermentation is vigorous using healthy yeast. Allow full attenuation. Leave beer on yeast longer. Oxygenate wort fully. Try another yeast strain. Make sure sufficient yeast nutrients are available. Let beer age longer.p


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## MHB (10/8/17)

Why are you trying to ferment at 15-18oC, Most ale yeast will be impeded below 16oC, having the temperature wander back and forward under 16oC could be quite a big stressor.
Better to ferment at >18oC and get a quick clean ferment.
The info on M44 recommends fermenting at 18-23oC, recommends sprinkling onto the wort rather than re-hydrating. So that's two things you are doing that the manufacturer doesn't recommend - try doing it their way and see if that improves the performance.
Mark


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## klangers (10/8/17)

MHB said:


> Why are you trying to ferment at 15-18oC, Most ale yeast will be impeded below 16oC, having the temperature wander back and forward under 16oC could be quite a big stressor.



I had exactly the same issue as AHB, but simply because I underestimated the self-heating effects of a cider fermentation, didn't put a heater on the controller, and it went too cold and then swung around a bit. Very sulphurous on the nose, and horrendous solventy acetalhyde. 

Whereas the cider that went hotter and quicker is clean as a whistle.


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## Adr_0 (10/8/17)

I've used MJ's Empire Ale in a beer and it's come out great - this was a 9-10L batch and there was a bit of temperature variability but it was over summer so no heating in the freezer.



klangers said:


> I had exactly the same issue as AHB, but simply because I underestimated the self-heating effects of a cider fermentation, didn't put a heater on the controller, and it went too cold and then swung around a bit. Very sulphurous on the nose, and horrendous solventy acetalhyde.
> 
> Whereas the cider that went hotter and quicker is clean as a whistle.


Yes, this is exactly what happened.



MHB said:


> Why are you trying to ferment at 15-18oC, Most ale yeast will be impeded below 16oC, having the temperature wander back and forward under 16oC could be quite a big stressor.
> Better to ferment at >18oC and get a quick clean ferment.
> The info on M44 recommends fermenting at 18-23oC, recommends sprinkling onto the wort rather than re-hydrating. So that's two things you are doing that the manufacturer doesn't recommend - try doing it their way and see if that improves the performance.
> Mark



I had set my freezer to 16.5°C expecting that M44 would be like US-05 (15-22°C) or BRY-97 (15-22°C) and so that would be an appropriate setpoint to start. Without heating it dropped to 14.8 or 15°C and then I let it warm up to 17, 18 then 19°C and it progressed steadily from there. Keep in mind my point/query is around flexibility and accommodation of some temperature fluctuations vs liquid strains.

I put a freshly brewed hefeweizen in the freezer (still 25°C or so from post chilling) and had the freezer set to 17°C, but unfortunately an IPA that was in there too got down to 12-13°C, and a couple of days later is now in the mid 18's. This was using 1275. It hiccuped in the attenuation but still tastes very clean.

The M44 ferment took 30hrs to form any sort of krausen, while the 1275 IPA had a good krausen after 6-7hrs and had a great starter, etc. I would probably put the acetaldehyde down to temperature swings/heating but the 1275 batch rode through it a lot better - which makes me think it's possibly cell count/vitality.

An MJ saison had a similar experience and was tasting excellent until having some temperature swings in the mid-high 20's where the acetaldehyde just rocketed up. Sure, that sounds pretty rough but I've had the Dupont strain do a similar thing while sitting outside and produce a stunning, clean beer - clean in terms of acetaldehyde anyway.

Brulosophy had a batch of 1056 swing from 19 to 30°C up and down a few times and got some off flavours from it but no acetaldehyde and nothing majorly horrible. I wonder if the liquid strain was a little more resistant than a dry strain - though I don't recall ever getting much/any acetaldehyde from US-05.

It's a hypothesis. I'm not saying that dry yeast with rock solid temperature will produce acetaldehyde, I'm wondering if due to the drying process, due to perhaps being optimistic about cell count, dry yeast - or just MJ's? - is not as resistant to non-ideal conditions as liquid strains.



ein stein said:


> why is your temp swinging so wildly?
> im using an incandescent bulb as my heat source but i painted it with black stove paint and let it cure by leaving it on for a day (lots of fumes came off it) and i only get temp variations of 0.3c which is the minimum i can set my stc to. ive only been using dry yeast but have never had major issues with acetaldehyde.


Yeah I've got a Keg King controller. It's got an SS thermowell which creates a bit of lag in picking up the temperature. When it's just heating or just cooling it's fine, but I've probably had the hysteresis set too finely when freezer and heating are both on.



Dae Tripper said:


> Stright from the BJCP website (lol BJ)
> *Characteristic* *Possible Solutions
> Acetaldehyde*fresh cut green apples Make sure fermentation is vigorous using healthy yeast. Allow full attenuation. Leave beer on yeast longer. Oxygenate wort fully. Try another yeast strain. Make sure sufficient yeast nutrients are available. Let beer age longer.p


Thanks.


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## MHB (10/8/17)

Couple of points
First up please don't read/quote Brulosophy, they aren't a reliable source and that's putting it very gently.
Yeast is temperamental, if you are going to brew Ale and you don't have good temperature control pitch and ferment around 18-20oC, nearly all Ale yeast will preform well in this range, couple of exceptions being Saison and Kölsch.
Put a small fan in your fermenting fridge, it will keep the temperature more consistent, provide some gentle heating at need, and will keep your ferment closer to the set point. remove all other heaters (belts, plates, light globes...)
Always look up the manufacturers recommendations for pitch rate, fermenting temperature and how/whether to re-hydrate. Poor re-hydration practice can kill or cripple a lot of the dry yeast, if you off half the dry yeast, no surprise if preforms worse than a liquid yeast.
In my experience/opinion both Dry and Liquid yeasts preform equally well if treated appropriately. The only reason to chose one over the other is available strains, I don't think there is a dry Hefeweizen as good as some of the liquid cultures, so would choose a liquid for a heffe, same for Saison and Kölsch. For most production beers quality dry yeast is fine I use a fair amount of S-04.

Odds on from what has been posted so far the problem is really a lot closer to home than the yeast maker.
Mark


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## Adr_0 (10/8/17)

You're absolutely right on all of those points Mark. MJ's do recommend rehydration, one pack for 23L of (presumably standard wort) and both packs were rehydrated together to form a nice bubbly cream - so I think the rehydration went well - and pitched into 23L of 1.040 wort. Dechlorinated tap water, "not cold" and stirred frequently. I'm not denying my poor practices are 90% of the problem - in the last few years I've only really had acetaldehyde 3 times, and each time has been dry yeast using the heating lamp - but most of the time the beers are fine.

I'm basically saying that yes in these instances I've had bad practices, but I've used a heating lamp at other times and have had no such problems making me think that these yeasts aren't as tolerant of poor practice as liquids. You said "both Dry and Liquid yeasts perform equally well if treated appropriately" which is no doubt true but perhaps dry yeasts need a little more than just rehydration to get on a level playing field? I'm keen to try it again starting at 18.5 up to 21/22 as I've heard good things about it.


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## MHB (10/8/17)

If you are going to re-hydrate, make sure you get the temperature right (have a good thermometer) they (Mangrove Jacks) recommend re-hydrating Ale at 30-35oC, in 100mL of water and stirring for 8-12 minutes.
It is also a very good idea to "Attemperate" your yeast to the wort temperature in steps of not more than 5oC at 5 minute intervals (some people say 10oC steps, 5oC is safer).
If you had 100mL of yeast cream, add a little wort (say 10mL at 20oC), stir, wait 5 minutes, add another 10mL, stir... I use my glass lab thermometer to do the stirring and measuring at the same time. Prevents another case of yeast shocking that can kill or inhibit the yeast.
I'm often bemused (well was going to say amused... but not the right word) by people saying "they re-hydrate properly" when what they appear to mean is "chuck the yeast in some water... and cross their fingers".
Look after your yeast and it will make good beer.
Mark


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## Adr_0 (10/8/17)

That's an interesting point. Both dry and liquid packets I leave out for a few hours and then sit in a water bath either with starter wort or just water, then make up the starter or the rehydration mix. But only the liquid yeasts do I draw off wort from the batch and buzz it on the stirplate - the dry yeasts I just pour straight in. I of course make sure that the temperatures are close - comfortably within 10°C - but perhaps I should be rehydrating in a small flask then adding some wort.

Incidentally I'm not sure how accurate your glass thermometer is when it's only submerged an inch or two - unless you're making 1L rehydration mixes and have it 2/3 submerged as required.


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## MHB (10/8/17)

Most thermometers are either total immersion or 76mm immersion, mine is the latter so it isn't hard to get 76mm of it into the yeast slurry.
Where do you get the 2/3 from, sort of thing those wholly educated on Brulosophy could come up with, wrong for both sorts of thermometer and misleading, without any foundation in fact.


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## MHB (10/8/17)

PS I really hate Brulosophy
M


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## technobabble66 (10/8/17)

I'd be guessing the issue is the small starting population plus the temp variance.
If the temp is held relatively stable in the right range, the amount pitched from a sachet (11g?) should be fine and produce a good, clean result (even though 11g of dried yeast is a relatively small starting population for a ~23L, ~1.045 beer; i think it needs to double its population a few times to reach the "appropriate" population number). 
If you had a large/"appropriate" population, you'd probably be able to withstand some temp fluctuations without flaws developing in the beer.
Unfortunately i'd suspect it that you've had the combination of both a small (though well primed) starting population plus the substantial temp fluctuations.

Admittedly that doesn't necessarily explain why the liquid was fine (i'm assuming you're pitching from the (relatively fresh) vial, whereas the dry was flawed. I can only assume the additional stress of rehydrating (in general, not the specific step the manufacturers recommend) & coming back to life is what makes the difference compared to liquids.
So maybe it's that latter point that really means the other 2 variables when occurring together can produce a flawed beer.

2c

Obviously you need more practice and simply have to brew more.


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## manticle (10/8/17)

MHB said:


> PS I really hate Brulosophy
> M




But haven't you read the one where they did something and no-one could tell the difference? There were like, six people, all drinking beer and NO-ONE could tell the difference. That proves it.


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## Adr_0 (10/8/17)

MHB said:


> Most thermometers are either total immersion or 76mm immersion, mine is the latter so it isn't hard to get 76mm of it into the yeast slurry.
> Where do you get the 2/3 from, sort of thing those wholly educated on Brulosophy could come up with, wrong for both sorts of thermometer and misleading, without any foundation in fact.


I'm unfortunately lumped with a total immersion thermometer - but have found no visible change in reading when it's 2/3 immersed vs full and which tends to work better for me when measuring mash temperatures. My wife has temperature resistant hands but mine are very delicate. Anyway, while I was being a smartarse I was thinking we're getting into the few % level with starting to critique my rehydration method.



MHB said:


> PS I really hate Brulosophy
> M


I hope you're a fan of irony. 90% of the time I'm having a go at those guys - typically wrong recipe for what they're testing, though I think in 100% of cases their tasting group is too inexperienced - but I've floated one article here for discussion.



technobabble66 said:


> I'd be guessing the issue is the small starting population plus the temp variance.
> If the temp is held relatively stable in the right range, the amount pitched from a sachet (11g?) should be fine and produce a good, clean result (even though 11g of dried yeast is a relatively small starting population for a ~23L, ~1.045 beer; i think it needs to double its population a few times to reach the "appropriate" population number).
> If you had a large/"appropriate" population, you'd probably be able to withstand some temp fluctuations without flaws developing in the beer.
> Unfortunately i'd suspect it that you've had the combination of both a small (though well primed) starting population plus the substantial temp fluctuations.
> ...



I pitched 20g and from what I could tell of the foamy rehydration I had fairly good viability. Meanwhile the 1275 was 8-9mths old, but was built up carefully. I'm not a total idiot and do have some degree of experience - good thick krausen after 6-7hrs and fast, clean ferment hopefully reflecting that.

I absolutely take a good chunk of the blame for temperature swings but I do raise the question of cell counts in the MJ's packets. Somebody somewhere - I'll dig up the post/article - took some counts and found they were a bit short.

And I definitely need more practice with dry yeasts. Luckily the hefeweizen I've just done has perfect temperature rise and is a good liquid strain so that might turn out ok.


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## technobabble66 (10/8/17)

20g into 20-25L?
If so, you're right: should've been fine to resist a little temp fluctuation, I would've thought.

If 20g into, say 40L, I think my point still stands.

Edit: oh, and the liquid was carefully built up? Again, backs the idea the liquid yeast would simply be in more optimal health by the time it hits the FV.


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## Danscraftbeer (10/8/17)

On swinging temp control I wonder If I've gone overboard. Thermowell in 50lt kegmenter I really do control temps now.
That means literally resisting the brew from rising itself in temp. That almost seems unnatural but that's what the commercials do? 
Dry versus Liquid Yeasts I've found the dry yeasts are more hardy (if hydrated carefully). Liquid yeasts you have to build up more, more vulnerable to transport temp variations so its harder to transport with much shorter life but you get a much broader and exotic range.


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## MHB (10/8/17)

manticle said:


> But haven't you read the one where they did something and no-one could tell the difference? There were like, six people, all drinking beer and NO-ONE could tell the difference. That proves it.


Is that the one where someone shat in the kettle......
Mark


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## paulyman (10/8/17)

manticle said:


> But haven't you read the one where they did something and no-one could tell the difference? There were like, six people, all drinking beer and NO-ONE could tell the difference. That proves it.



Must have missed that bit. I only read the part of the article where they analysed the results looking for some deeper meaning anyway.


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## contrarian (10/8/17)

But the plural of anecdote is data, everyone knows that!


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## manticle (10/8/17)

MHB said:


> Is that the one where someone shat in the kettle......
> Mark



Think that one had twelve tasters.
Double the fun


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## indica86 (11/8/17)

I have not had any issue with MJs Saison strain.
I use that one on the bench in summer. Air temp fluctuates between 35° and 20°c.


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## Adr_0 (11/8/17)

indica86 said:


> I have not had any issue with MJs Saison strain.
> I use that one on the bench in summer. Air temp fluctuates between 35° and 20°c.


I've done the same with other saison yeasts and would have done so with this one, but suspect I cooked it too hard. Definitely keen to give it another go as it was tasting amazing up to the last few days of fermentation.


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## Adr_0 (11/8/17)

See one person says dry yeasts are more robust, while others say they need to be rehydrated very carefully.

I'm also curious about vitality and given they've typically been grown under conditions with adequate O2 this should be solid - but that's only been reported by Fermentis. Do other manufacturers state the same thing? MJ's mention oxygenation in their product sheet:
"After pitching Mangrove Jack’s Beer Yeast to your wort, you will experience a lag period which varies from strain to strain, and from beer to beer; 12-24 hours is normal. The lag phase will also be impacted by the degree of oxygenation of your wort and by temperature"
vs Fermentis:
*"Does the wort need Oxygenation/ aeration?*
As the yeast is grown aerobically, the yeast is less sensitive on first pitch. Aeration is recommended to ensure full mixing of the wort and yeast."

I'm also very curious if there are differences in cell counts with MJ yeasts, and even yeast to yeast. While datasheets all point to >5 or 6bn cells per gram, Brewer's friend cites the following:
*Yeast* *B cells/g*
Safale__ K-97__14
Safale__ S-04___8
Safbrew_T-58__18
Safbrew_S-33__16
Saflager_S-23__10
Saflager_S-189__9

The reference I found on Homebrewtalk is pretty shallow, so I won't quote it here. Suffice to say that MJ's also report >5/6bn per gram.

I'll keep digging, and also need to try M44 packs mixed into wort and kicked off at 18°C or so, then rising into the 20/21 range.

I'd like to improve my dry yeast practice though. I'm almost there with liquids but I would say I have a way to go with dry yeasts and would like to get on top of them as my excellent LHBS stocks a good range.


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## MHB (11/8/17)

MJ report more than (>) 5*10^9 cells/g so in the 10g pack 5*10^10, Wyeast and White labs both claim to have 1*10^11, about twice as much, but they cost twice as much so - meh much of a muchness on cost.
What really concerned me was the temperature wandering back and forward around the 15oC range. For most Ale yeast there is somewhere between 14-16oC a minimum temperature, under which it goes dormant. by not having good control of temperature the yeast is "switching" on and off, it preforms about as well as you or I would if someone kept waking us up every 2 hours - a day or two of that and we would be knackered!
If you get a decent population of viable yeast and let it do its thing you will get decent beer.

Using the recommended pitching rate for Ale yeast (0.4-1*10^6 cells/mL/point of Plato) 10g in 23L of 1.050 wort
(0.4*10^6)*23,000*12.5 = 115,000,000,000 or 1.15*10^11. About half the recommended minimum pitch.

Yeast needs Oxygen to reproduce, so clearly there is going to be a benefit to aerating your wort, along with everything else than needs doing properly, temp control, wort nutrients...
Mark


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## Adr_0 (11/8/17)

MHB said:


> MJ report more than (>) 5*10^9 cells/g so in the 10g pack 5*10^10, Wyeast and White labs both claim to have 1*10^11, about twice as much, but they cost twice as much so - meh much of a muchness on cost.
> What really concerned me was the temperature wandering back and forward around the 15oC range. For most Ale yeast there is somewhere between 14-16oC a minimum temperature, under which it goes dormant. by not having good control of temperature the yeast is "switching" on and off, it preforms about as well as you or I would if someone kept waking us up every 2 hours - a day or two of that and we would be knackered!
> If you get a decent population of viable yeast and let it do its thing you will get decent beer.
> 
> ...


If we're talking minimum pitch, to be honest I'm not that far above it:
(0.4*10^6)*23,000*10° = 92 x 10^9 and given two packs were added that's 100x10^9

So yes, I'll try again at higher/stable temperature, but looking at those numbers I'm thinking I need to be doing a bit of growth and some oxygenation.

I think people take what Fermentis says seriously - essentially that their dry yeast doesn't need oxygenation on the first pitch [if pitched in the correct viable cell quantity]. So is this another one of those things where what's written on the box doesn't reflect best practice? Sounds to me like starters with dry yeast are the go.


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## MHB (11/8/17)

Agreed in part, when they harvest yeast for drying its is crash chilled/centrifuges/filtered... when its at its peak sterol content, not what we as home brewers do.
Commercially harvested dry yeast will go through a full life cycle without additional Oxygen, not saying there aren't advantages to wort aeration, just not as many as with liquid cultures and especially home cropped yeast.
Taint brewing fun.
Mark


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## Adr_0 (11/8/17)

MHB said:


> Agreed in part, when they harvest yeast for drying its is crash chilled/centrifuges/filtered... when its at its peak sterol content, not what we as home brewers do.
> Commercially harvested dry yeast will go through a full life cycle without additional Oxygen, not saying there aren't advantages to wort aeration, just not as many as with liquid cultures and especially home cropped yeast.
> Taint brewing fun.
> Mark


I just realised as well that the "0.4" in your calculations could even potentially be 0.5 or 0.7/0.8 and should be higher again for lagers.

I always love improving, so this is great to know for dry yeasts and I can make some easy changes that should result in some good improvements.


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## Lionman (11/8/17)

MHB said:


> Agreed in part, when they harvest yeast for drying its is crash chilled/centrifuges/filtered... when its at its peak sterol content, not what we as home brewers do.
> Commercially harvested dry yeast will go through a full life cycle without additional Oxygen, not saying there aren't advantages to wort aeration, just not as many as with liquid cultures and especially home cropped yeast.
> Taint brewing fun.
> Mark



What sort of time does it take for the yeast to go through a generation? Should o2 addition be delayed with using dry yeast? A day after pitch?


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## MHB (11/8/17)

No, we then go back to the yeast changing what it's doing, in this case switching back and forward between its reproductive, aerobic fermentation and anaerobic alcohol producing stages, the switching back and forward will "stress" the yeast, consuming vital nutrients and reducing the vitality of the whole population.
If you want to understand yeast, the first rule is that yeast wants to make yeast not beer.
Don't confuse the yeast, if you are going to pitch a lower than optimum population expect the ferment to take longer and to produce more side-issues (which adds its own complexities), be prepared to rack the beer to get off old/dead/stressed yeast, if you want to avoid the problems that can arise from too long a contact between old/stressed yeast and beer, golden rule is 14 days max contact with primary yeast.
Or pitch an adequate population of healthy yeast into a well aerated wort and let it do its thing.
Mark


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## Adr_0 (30/8/17)

I'm pretty sure I know the answer to this question, but I'll ask anyway.

I've just (deliberately) grabbed a single pack of dry yeast for a beer next week. Although it technically undoes some of the convenience, there are no issues with building up cell count in a starter are there? Should I also rehydrate before throwing into the starter wort?


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## MHB (30/8/17)

Lionman said:


> What sort of time does it take for the yeast to go through a generation? Should o2 addition be delayed with using dry yeast? A day after pitch?


Under 'Ideal" conditions as little as 90 minutes, probably about 120 in a well aerated wort.
If you have a look at the instructions on the Saf website

*REHYDRATION INSTRUCTIONS: *Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 25 to 29°C (77°F to 84°F).
Leave to rest 15 to 30 minutes.
Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel.
Alternatively, pitch the yeast directly in the fermentation vessel providing the temperature of the wort is above 20°C (68°F). Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. *Leave for 30 minutes, then mix the wort using aeration or by wort addition.*

Probably pretty good procedure, gives the yeast time to hydrate and attemperate, then hit it with O2 to give it a real kick in the right direction.
Mark


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## bradsbrew (30/8/17)

MHB said:


> Under 'Ideal" conditions as little as 90 minutes, probably about 120 in a well aerated wort.
> If you have a look at the instructions on the Saf website
> 
> *REHYDRATION INSTRUCTIONS: *Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 25 to 29°C (77°F to 84°F).
> ...


Rehydrating yeast for 30 minutes prior to adding to wort negates the need to let sit for 30 minutes after sprinkling?


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## MHB (30/8/17)

Perhaps, tho every time yeast is moved to a new environment it has to adjust (attemperate) the adjustments take time and energy that all detract from what the yeast has stored to do the job of reproducing/brewing that we have planed.
I suspect it wouldn't make a major difference to the yeasts population or vigor, but its all cumulative the best process is I suspect the simplest.
Mark


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## Lyrebird_Cycles (30/8/17)

Lionman said:


> What sort of time does it take for the yeast to go through a generation?



Under ideal conditions _S cerevisiae_ doubling time is about 90 minutes. You won't achieve this in wort, more typical doubling times in the exponential phase in wort are 3 - 4 hours.


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## Bribie G (30/8/17)

MHB said:


> No, we then go back to the yeast changing what it's doing, in this case switching back and forward between its reproductive, aerobic fermentation and anaerobic alcohol producing stages, the switching back and forward will "stress" the yeast, consuming vital nutrients and reducing the vitality of the whole population.
> If you want to understand yeast, the first rule is that yeast wants to make yeast not beer.
> Don't confuse the yeast, if you are going to pitch a lower than optimum population expect the ferment to take longer and to produce more side-issues (which adds its own complexities), be prepared to rack the beer to get off old/dead/stressed yeast, if you want to avoid the problems that can arise from too long a contact between old/stressed yeast and beer, golden rule is 14 days max contact with primary yeast.
> Or pitch an adequate population of healthy yeast into a well aerated wort and let it do its thing.
> Mark


The old time UK brewers knew what they were doing and collected their yeast for repitching either from top cropping of yeast that rose to the surface, from the "barm deck" of a Yorkshire Stone Square, or from the troughs in Burton Union systems where it had likewise been expelled from the beer and was sitting there in a more or less pure state. 

Not (as we home brewers tend to do) from the sludge at the bottom of the fermenter when they got round to cleaning it out.


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## Adr_0 (29/9/17)

So this is rather anectodal, but after my previous experience I decided to do another beer (1.056, 16.2L requiring ~224bn cells) with 2 x packs of M44 and put it through a couple of growth starters and a vitality starter (1L, 1.8L, 500mL). So I likely had absolute shitloads more yeast vs the first one, but the setpoint was also raised 2°C just to get the true purity of the anecdote.







So no real surprises here, but after looking back through the first brew I had bumped up the temperature to 18, 19 then 20 and swirled quite a bit at the 23% attenuation mark. I would have thought that if there was adequate yeast the attenuation would have dropped fairly rapidly but it did not. I thought gravity/volume triggered yeast multiplication but I guess it's also sensitive to pitching temperature to the tune of <2°C?

The instructions on the M44 pack say "Sprinkle contents on up to 23L of fresh wort" so I'm going to call bullshit on that. I'm fine to do starters - now that I know I have to - but I think that statement is drawing a pretty long bow.

Has anyone done cell counts on it that anybody knows of?


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## Lyrebird_Cycles (29/9/17)

Adr_0 said:


> I thought gravity/volume triggered yeast multiplication but I guess it's also sensitive to pitching temperature to the tune of <2°C?
> 
> Has anyone done cell counts on it that anybody knows of?



Typical dry yeast has a cell count around 10^10 cells per gram so an 11 g pack is around 10^11 cells.

The triggers to yeast muliplication are more complex than is generally appreciated: a yeast cell that is about to bud will send out a signal compound, if there are enough other cells doing the same thing the concentration of the compound will rise to a level that triggers growth. The minimal cell count for this to occur is about 10^6 cells /ml. IIRC the stimulus for the signal compound is uptake of an appropriate carbon source (eg sugar) and the onset of mitosis.


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## Adr_0 (29/9/17)

It's a curiosity but it's basically not the core issue with that particular beer. I suspect that the growth enzymes are firing at the start and if starting conditions (including cell count and temperature) aren't right then more cells won't be there later in the fermentation. I am still mildly curious why a required range of (0.5 to 1) x 20,000 x 10°C = 100-200bn cells required and supposedly 200bn cells pitched (at 10 x 10^9/gram x 20g) didn't finish stronger.

I'm just going to have to err on the cautious side, build up dry yeasts and just go with it.

And get a microscope. And haemocytometer. And some micro pippettes. And some beer.


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## Adr_0 (3/10/17)

Lyrebird_Cycles said:


> Typical dry yeast has a cell count around 10^10 cells per gram so an 11 g pack is around 10^11 cells.
> 
> The triggers to yeast muliplication are more complex than is generally appreciated: a yeast cell that is about to bud will send out a signal compound, if there are enough other cells doing the same thing the concentration of the compound will rise to a level that triggers growth. The minimal cell count for this to occur is about 10^6 cells /ml. IIRC the stimulus for the signal compound is uptake of an appropriate carbon source (eg sugar) and the onset of mitosis.


I have to ask... Have you done any yeast cell counting before? I presume you have access to the equipment and you certainly have the expertise.


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## Lyrebird_Cycles (3/10/17)

Oh the hours I've spent counting bloody yeast. 

But no, I don't have my own microscope or haemocytometer. I can get access to same if needed.


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