# Pitching Dry Yeasts



## BKBrews (31/8/16)

I've now done a handful of brews and only ever used dry yeast. After purchasing the grainfather, my next batch will be the first larger scale (23L).

I've been using US-05 and what is written on the packet is different to what is on the product information from their website. The website says to re-hydrate using wort that equals 10x the weight of the yeast @ 27 degrees +- 3 degrees. Stir until creamy, let sit for 30min, then slowly stir for a further 30min.

I have been taking the wort from the kettle during the boil and allowing this to cool to pitching temp. From there, I've sprinkled in the yeast, stirred it in, then covered until I'm 30min from pitching. When I'm 30min from pitching, I uncover it and continue to stir for 20 - 30min, then pitch directly to the fermenter.

Is this best practice? I know a lot of people say to sprinkle directly into wort (including the packet saying that), but if I want to re-hydrate am I going about it the best way? I've seen that some people just re-hydrate into water, but I read somewhere that this can damage the cell walls.

I want to try some interesting liquid yeasts eventually, but find the whole starter thing a bit daunting at this stage.


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## SBOB (31/8/16)

You definitely want to rehydrate ( I'm not getting into that debate though), but I doubt you would see any difference between hydrating in water compared to wort.


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## BKBrews (31/8/16)

> You definitely want to rehydrate ( I'm not getting into that debate though), but I doubt you would see any difference between hydrating in water compared to wort.


Interesting. If I continue to use wort (as per the website instructions), is taking it from about 30min into the boil OK?


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## TheWiggman (31/8/16)

If rehydrating it should be done in water, not wort. Pitching into wort will defeats the purpose.. Here's a quick online excerpt:

_"The idea is to combine water and dry yeast in order to “wake up” the yeast and restart its metabolism. When pitched directly into wort, the sugars that are present can prevent the yeast cells from drawing enough water through their cell membranes to kick start their metabolism."_


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## Yob (31/8/16)

fcuk me.. really? again?

If you are going to the trouble of rehydrating, *use water for best yeast health*, after 15 minutes you can gently stir and add a bit of wort if you like, pitch within 30 minutes


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## pcqypcqy (31/8/16)

I only use dry yeast. Not from any informed brewing preference or style, just because I haven't added yeast rehydration / handling liquid yeasts into my skill set yet.

For 6 gallon batch as you propose, I usually pitch two packets of dry yeast straight into the wort when it has reached pitching temp. Since I've been doing this I've had no problems. I DID have problems previously trying (and badly) to rehydrate dry yeast using no technique and getting it wrong most of the time.

So I'm going to say that at this scale, using dry yeast out of the packet should be fine. My understanding is that once you get talking about bigger batches and higher gravities (like barley wines), then yeast health becomes more critical. Possibly also for lagers where off flavours can be crucial.

I know there's a good debate on the merits of rehydrating yeasts, and I don't want to get involved in that. I just know this works for me for the sorts of beers I brew (usually ales, strongest being around 6.5%).


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## Killer Brew (31/8/16)

Shouldn't be an issue as would be well and truly sterile at that point. Only question would be of gravity. What does the website suggest? Also ensuring it is at the correct temp obviously. I just go with water.

Or just listen to the experts above and use water.


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## Rocker1986 (31/8/16)

What Yob says is what I do. I don't add wort to it but I let it sit 15 mins or so, then whack it on the stir plate on low speed until it's a cream and pitch, I always make sure I pitch within 30 minutes too. It works really well in my experience. I haven't dry pitched yeast into wort for a long time.

My view is that yeast health is one of the most important aspects of brewing, for all beers not just high OG ones, and one that many overlook. I don't profess to know as much as Yob about it, but it is something that I'm putting in a fair bit of time to learn about.


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## kaiserben (31/8/16)

BKBrews said:


> I've seen that some people just re-hydrate into water, but I read somewhere that this can damage the cell walls.



Are you sure about that? I've read the opposite. That with dried yeast, the cell walls can be overwhelmed by the sudden introduction of sugars before the cells have had the chance to establish themselves with strong walls. 

I've read that dry pitching directly into wort sees sugars burst through cell walls and can kill off about half your cells. (whether you're pitching into your fermenter or into a little starter is exactly the same. Both are pitching into wort). 

Just rehydrate with water.


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## Yob (31/8/16)

*^^^^^* *THIS* *^^^^^*


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## kaiserben (31/8/16)

BKBrews said:


> I want to try some interesting liquid yeasts eventually, but find the whole starter thing a bit daunting at this stage.


Just do it. It's easy once you've done it once. 

If nothing else it should steer you in the direction of making sure your pitching rates are correct - thus making better beer.


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## BKBrews (31/8/16)

> Shouldn't be an issue as would be well and truly sterile at that point. Only question would be of gravity. What does the website suggest? Also ensuring it is at the correct temp obviously. I just go with water.
> 
> Or just listen to the experts above and use water.


The website is very vague and just says water or wort - no mention of how you're supposed to obtain the wort.

One brew I was kind of pissy and accidentally pitched the dry yeast into sanitised water - still my worst beer to date.


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## Rocker1986 (31/8/16)

That is my understanding of it too kaiserben. It wasn't the reason I began re-hydrating yeast, I did that because pitching dry onto a huge foam layer after the wort was tipped into the FV from a cube seemed rather daft. This practice lasted one batch. I wanted the yeast in the wort ASAP so began re-hydrating. It was only later that I learned about the osmotic pressure from the wort bursting cell walls and such, which only added to the reasons to re-hydrate it to me.


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## BKBrews (31/8/16)

The website and package also says 11.5g is sufficient for 20 - 30L of wort - why are people using 2 packets for 23L batches?

Thanks for the help everyone, I'll give boiled water a go this time. Hopefully after I have a few brews on the grainfather under my belt, I'll be able to experiment with all different kinds of yeast.


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## Killer Brew (31/8/16)

This would be 2 packs for above certain gravity. Use a pitch rate calculator like Brewer's Friend. Can be applied to dry or liquid yeast.


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## Rocker1986 (31/8/16)

BKBrews said:


> The website and package also says 11.5g is sufficient for 20 - 30L of wort - why are people using 2 packets for 23L batches?


Depends on the OG of the wort. The cell count per gram seems a bit of an unknown as well. Some say 20 billion per gram, others say 10 billion. Fermentis says minimum 6.9 billion at packaging. The amount of dry yeast recommended will vary depending on what cell count the calculator uses.

I find liquid yeasts easier for this because you can work off a cell count rather than weight. Most calculators will say you need X billion cells for a given batch, so you can either buy enough yeast to get there or build it up in a starter.


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## mmmyummybeer (31/8/16)

I'm guessing this has got to be the most discussed forum topic ever and does bring a smile to my face when it comes up. Just waiting for the explosion of replies. mmm to rehydrate or not rehydrate that is the question.

Anyway might as well add my 2 cents while I'm here.

There is really is more important things to concentrate on, but if you want to get technical on the rehydrate from what I understand a wort and water mix is the best. Reason being is due to the osmotic pressure from the sugars on the ​​yeast. Some of the yeast cells may not survive going straight into the wort and having a small amount of wort in the water is more gentle on the yeast. One could argue just add more yeast and let natural selection run its course


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## kaiserben (31/8/16)

BKBrews said:


> The website and package also says 11.5g is sufficient for 20 - 30L of wort - why are people using 2 packets for 23L batches?
> 
> Thanks for the help everyone, I'll give boiled water a go this time. Hopefully after I have a few brews on the grainfather under my belt, I'll be able to experiment with all different kinds of yeast.


There are yeast pitching calculators around the internet (I use Yeastcalculator.com, there's also MrMalty.com) and your optimum* number of cells to pitch will depend on many factors, like style of beer (lagers require more yeast cells), gravity (more cells is optimal for higher gravity) etc. 

You also have to take into account the how old your pack of yeast is (the number of healthy cells die off the longer it is since the pack was produced). 

* Optimum is the important word here, because 1 very fresh pack might get the job done, but might also give you more yeasty esters in your finished beer because they are under more stress than they would have been if you'd pitched the optimum number of cells.


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## pcqypcqy (31/8/16)

BKBrews said:


> The website and package also says 11.5g is sufficient for 20 - 30L of wort - why are people using 2 packets for 23L batches?
> 
> Thanks for the help everyone, I'll give boiled water a go this time. Hopefully after I have a few brews on the grainfather under my belt, I'll be able to experiment with all different kinds of yeast.


I was using one packet for my first few brews, but had some slow / non starters. Possibly as a result of what the other guys have said before, maybe dry pitching does kill half your cells, I don't know. However since I went to two packets this hasn't been an issue. Packets say a lot of things, but given my experience with it and the risk of wasting $50 odd worth of ingredients, I spend $5 more as insurance.


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## Rocker1986 (31/8/16)

mmmyummybeer said:


> There is really is more important things to concentrate on, but if you want to get technical on the rehydrate from what I understand a wort and water mix is the best. Reason being is due to the osmotic pressure from the sugars on the ​​yeast. Some of the yeast cells may not survive going straight into the wort and having a small amount of wort in the water is more gentle on the yeast.


I'm confused by this. If some of the cells are going to be killed by osmotic pressure from the sugars in the wort bursting their walls, I can't see how adding any wort to the re-hydration water before pitching the yeast into it could be gentler on the yeast. Everything I've read on the subject recommends re-hydrating in water only.


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## BKBrews (31/8/16)

> There are yeast pitching calculators around the internet (I use Yeastcalculator.com, there's also MrMalty.com) and your optimum* number of cells to pitch will depend on many factors, like style of beer (lagers require more yeast cells), gravity (more cells is optimal for higher gravity) etc.
> 
> You also have to take into account the how old your pack of yeast is (the number of healthy cells die off the longer it is since the pack was produced).
> 
> * Optimum is the important word here, because 1 very fresh pack might get the job done, but might also give you more yeasty esters in your finished beer because they are under more stress than they would have been if you'd pitched the optimum number of cells.


Thanks for that - the mrmalty.com seems the least complicated for me at this stage. I didn't realise, but the beersmith calculator appears to be very similar to this. it's recommending about 17g for my next brew (an estimated 1.067 IPA), so 2 packets looks ideal. I've got a full pack and a 3/4 pack in my fridge, so will just use that this time and see how it ends up.


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## kaiserben (31/8/16)

Just remember to keep in mind to input the production date of your yeast pack (not the use-by date, which, from memory, is what's printed on some dried yeast packs). 

EDIT: For Fermentis - the date on the pack is 2 years AFTER the production date. So if the pack says "08-2017" you should enter Aug 31, 2015 as your date at MrMalty.


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## peteru (31/8/16)

Seems simple enough to me if you take a practical approach. Re-hydrate in water only and pitch into wort before the cells use up their energy reserves. If you already started the re-hydration process and can't pitch the yeast soon enough, you need to add some wort to the starter to kept the yeast fed.

As to the exact timing? I don't know. I would guess that a 10 minute hydration should do the trick and you probably need a fermentable addition after 30 minutes. Or it could be 3 and 10 minutes. I'm sure that the yeast manufacturers have a complex answer for this, but at the end of the day most home brewers would prefer a simple rule of thumb.


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## Lord Raja Goomba I (31/8/16)

The thing that got me rehydrating in water, was I used BRY97 and hate the lag time (I discussed this recently with someone). I rehydrated to shorten that time. Since then, there have been flame wars aplenty about it, but I've become a solid rehydrater.

To me the effort isn't too bad. I like the quick lead in times.

ATM I'm trialling some Mangrove Jacks yeasts to see what can go in the brewery dried yeast wise, before I get moving on a stir-plate build and yeast bank. To make the experiment fair, I rehydrate all as I use them. I've had the last 3 all take off pretty quick - I pitched two yeasts - one a wit, the other a west coast ale after rehydrating at 6pm last night, got up this morning at 6am to see some very healthy krausen.

That's the other thing I really like (even if it's just a peace of mind thing - fake or real) is that my krausens are usually more vigorous with a rehydrate. To me, that spells good yeast health.

Additionally, from the good krausens, I have grabbed a couple at high krausen, scooped and pitched into big beers - an RIS and an AIPA on the high (1.070) side and seen them take off like rockets.

All this anecdotal evidence has proved to me that I much prefer a rehydrate.


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## bradsbrew (31/8/16)

.


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## argon (31/8/16)

Prefer to hydrate... but sometimes I get lazy and just use 2 packets. Discernible difference = none


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## Hostage_85 (31/8/16)

I pitch using Dry Yeast, although want to try re-hydrating and getting into starters at some stage.

I've got a question slightly OT
Every batch I do, most of the recipes stated the FG should finish around 1.008 to 1.012. To date, I've never had a batch finish within that range.
The closest I've had is my latest one which is a Czech Pilsner which finished up at 1.014.

Do you think this would be due to Dry pitching and not re-hydrating?


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## Lyrebird_Cycles (31/8/16)

I know this has been done to death but I'm going to put my bit in anyway.


The best medium for rehydration is yeast rehydration medium made by the nutrient companies, such as Laffort's "Dynastart".

If you don't want to bother with using such, use ordinary water, preferably chlorine free. Do not use wort. DO NOT use nutrients.

Warm the water up to 38 to 39 degrees, use ten times the yeast weight in water.

Sprinkle yeast on top, if the layer is millimetres deep just leave it. If your vessel is narrow and the layer is deeper mix it very gently for a few seconds

Leave it rehydrate for 15 - 20 minutes. *Do nothing to it in this time.*

After this, agitate gently for a few seconds.

If your wort is ~ 20 degrees the yeast can go straight in. If your wort is under 15 degrees, add an equal volume of wort to the yeast slurry and mix. When krausen is apparent, add the slurry to the wort. Between 15 and 20 it's your call, probably better to do a shandy but the advantage is small.

Trust me on this, I've actually done the trials for all the components in the above and can confirm that they are the optimal combination.

The reasons are pretty simple: drying yeast stresses the hell out of it. Rehydrating it stresses it again. You want to be nice to the yeast in this phase.

You want water to pass though the membrane quickly to rehydrate the cell: warmth and low osmotic potential in the medium are optimal.

When the cell is part way hydrated there is a lot of stress on the cell wall, so mixing it at this stage will damage the cells.

The rehydration medium is warm, pitching it to wort with more than about 15 degrees temperature difference will inhibit the yeast: best to acclimatise gradually.

The action of the commercial rehydration media is somewhat controversial but I've been involved in extensive trials over the last 7-8 years and we have documented a reduced incidence of stuck ferments, even at very high sugar levels. At ordinary sugar levels I do not believe they are as important.


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## Vini2ton (31/8/16)

The Vatican insists all dry yeast be rehydrated in holy water. 2 packets too be sure too be sure. It's the attempuration (?) that's the pain in the arse. Sprinkle works with a few hail marys.


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## bjbear77 (31/8/16)

bradsbrew said:


> .


Good to see experienced brewers sharing your knowledge like this 

Hang in there BKBrew


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## Mozz (31/8/16)

Lyrebird_Cycles thanks for the info. Just checking. You say 38-39C. Substantially higher than the 28C suggested by Fermentis?

As my 2c I'm over the lag with dry yeast such as US05 rehydrating or not and now make a starter culture first. Maybe I've been unlucky with the batches I got through the post, but my brews have been taking up to 2 days to kick off pitching 0.75g per L.

Current brew (with starter) airlock activity started within a few hours and is already at FG after 5 days.
All advice is its unnecessary to make a starter if using dry yeast but I'm seeing a big advantage in predictability and noticeably cleaner beer quality.


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## Lyrebird_Cycles (31/8/16)

Yes, 38-39 oC unless there is a specific reason not to: the idea is to hasten the process by softening the cell wall*.

The usual reason for not allowing yeast to reach this sort of temperature is that it greatly increases the toxicity of alcohol*. Since there's none present at this stage, it's not a problem.

I can confirm that US05 happily survives 40 oC rehydration water and kicks off straight away.

*Both these things relate to the same phenomenon: the lipid bilayer of the cell wall is a liquid crystal which undergoes a phase transition (melting), usually around 35 oC.


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## Blind Dog (31/8/16)

I'm assuming DBS is taking the evening off?

Anyway, on a serious note, has anyone actually seen a properly conducted (so excluding brulosophy et al) study comparing the 'sprinkle' method of rehydration to rehydration in water and/or wort (sterile or otherwise)? I've only ever managed to find oblique references that never pan out to an actual study, statements without any supporting evidence and opinions. You'd think it would have been done given its a frequent topic here and on the related US site, and dried yeast is widely used in commercial operations


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## Lyrebird_Cycles (31/8/16)

References

Henschke, P.A. Preparing a yeast starter culture: fresh or dried yeast? Allen, M. (eds). Advances in juice clarification and yeast inoculation: proceedings of a seminar; 15 August 1996; Melbourne, Vic. Australian Society of Viticulture and Oenology: Adelaide, S.A : 17-21 ; 1997.
Monk, P.R. Rehydration and propagation of active dry wine yeast. Aust. Wine Ind. J. 1: 35; 1986.

Yes the references are old, this topic was put to bed twenty years ago.

Most of the work in the field is done for wine yeasts: must is a much tougher environment than wort* and the wine industry is a bigger market for the yeast suppliers because commercial breweries culture their own strains.

Commercial wineries also culture but yeast is never re-pitched* so the culture is started from rehydrated dry yeast, usually 2 x 500 g packets, then built up to an appropriate pitch level (in our case 8,000 litres of yeast culture at > 108 cells / ml for a standard white ferment). We measure the nitrogen status and the yeast counts on the cultures twice a day, giving us a good handle on how the well the rehydration has worked.

We go through hundreds of kilos of dried yeast each year and I personally put a lot of time and effort into training people to do it properly.
If "sprinkle" worked well we'd do it. It doesn't, so we don't.

* These things are related. By the time it's finished fermenting a must the yeast is knackered.


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## GalBrew (31/8/16)

Lyrebird_Cycles said:


> Yes, 38-39 oC unless there is a specific reason not to: the idea is to hasten the process by softening the cell wall*.
> 
> The usual reason for not allowing yeast to reach this sort of temperature is that it greatly increases the toxicity of alcohol*. Since there's none present at this stage, it's not a problem.
> 
> ...


I always wondered what the deal was with the instruction to rehydrate in the 20'sC, as all our lab yeast work is done much warmer.


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## Lyrebird_Cycles (31/8/16)

As I understand it, the original work was done by the late great Dr Paul Monk of the AWRI in the eighties (see ref 2 above). It then spread worldwide with the "flying winemakers" but some parts haven't caught up yet.

In the wine industry there are some specific strains that do not like rehydration at warmer temperatures but these are usually non-sacchs, used for things like tarting up the thiols in sauvignon bland. If a manufacturer recommends 20s across the range of yeasts I would simply ignore it and go for 38-39. If they change the recommended temperature with strain, then I would follow their instructions (but I'd also do a trial to see whether they are right).


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## manticle (31/8/16)

So upshot is that liquid is better than dry?


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## technobabble66 (31/8/16)

(Mainly @ Lyrebird Cycles: )
Out of interest, what are the strengths & weaknesses of the assumption that the optimal treatment of the wine yeasts are the same as the optimal treatment of both ale and lager yeasts? Namely in terms of what's going to produce the best ales or lagers, as opposed to the best yeast growth rates

Definitely not saying it's wrong, merely checking the veracity of what seems to be the main evidence for the way we treat our yeasts. I'm asking as I'm not knowledgeable about wine yeasts nor wine fermentation.

And i'm curious as to why all (i think) of brewing yeast suppliers would suggest 20-35°C for rehydrating (e.g.: 20-26 (fermentis lagers), 24-30 (fermentis ales), 25-30 (lallemand lagers), 30-35 (lallemand ales), yet you're reporting 38-39°C is optimal from your own studies (with wine yeasts, i assume?)?

Could it be that the beer strains are slightly different and are either optimised under slightly different conditions, &/or that though it might be sub-optimal for the growth of the yeasties, these lower temps are optimal for producing the best flavour profile in the beer? Just wondering.


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## skb (31/8/16)

manticle said:


> So upshot is that liquid is better than dry?


A lot of people seem to think so but I think this is for variety ... I have to say I love dry and use it more than liquid, and I have rarely entered comps but when I have most beer have been in top 5 and several have placed, and every time with dry yeast. I think dry yeast is easier to handle, cheaper, and less likely to introduce unwanted effects from starters. 

That being said I have two beers fermenting now one with liquid (WLP004) and one with my go to US-05.

In terms of rehydrating I have only recently started this, have not noticed difference so far but that may be because I am doing with US-05 which is such a work horse. I use the advised 15-30min. I need to try with S-23 as I have had some very slow starts and LONG fermentation, but I ferment at 12.5c with this yeast.

That's my 2 cents


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## manticle (31/8/16)

I was making a bad joke about another hotly debated hb topic.

Piss me take.


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## Blind Dog (1/9/16)

Lyrebird_Cycles said:


> References
> 
> 
> Henschke, P.A. Preparing a yeast starter culture: fresh or dried yeast? Allen, M. (eds). Advances in juice clarification and yeast inoculation: proceedings of a seminar; 15 August 1996; Melbourne, Vic. Australian Society of Viticulture and Oenology: Adelaide, S.A : 17-21 ; 1997.
> ...


Both being examples of the oblique references I've come across, usually phrased as 'Monk/Henschke suggests...' with a citation to the paper, but the papers themselves seem to be unavailable and the abstracts I've seen make no mention of an actual study of sprinkle into wort/must V rehydration. The other oft quoted reference is David Jenkin's (plus others) paper published by the IBD, but again it's not a study of one method versus the other.

Personally, I routinely rehydrate yeast in boiled and cooled water as it makes sense to gently wake them from their slumber, and it works. I've do occasionally sprinkle direct, but only when I'm being super lazy, and feel guilty. I'd just like to read a proper scientific analysis, just cos that's the way i am


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## Lyrebird_Cycles (1/9/16)

technobabble66 said:


> (Mainly @ Lyrebird Cycles: )
> Out of interest, what are the strengths & weaknesses of the assumption that the optimal treatment of the wine yeasts are the same as the optimal treatment of both ale and lager yeasts? Namely in terms of what's going to produce the best ales or lagers, as opposed to the best yeast growth rates
> 
> Definitely not saying it's wrong, merely checking the veracity of what seems to be the main evidence for the way we treat our yeasts. I'm asking as I'm not knowledgeable about wine yeasts nor wine fermentation.
> ...


The strength of the assumption is that it's based on the known physiology of _Saccharomyces spp_ and they're all more alike than they are different.

The weakness of the assumption is that if I'm wrong the yeast will be severely compromised by the higher temperatures: the general temperature profile of things like this is a slow increase up to the optimal temperature and then a sharp decline above it as things denature.

I have tried rehydrating at 40 oC on two of the more popular lager yeasts, W34 and S189, and three of the more popular ale yeasts, US04, US05 and Nottingham; they all work well. I think this is enough to rule out denaturation of major enzymes. I did not do post-rehydration viabilities, if I get time I might do that soon.

I don't know the reasons for the rehydration recommendations, but I suspect that the companies are dumbing things down for amateur brewers and untrained craft brewers.

If you use the wine yeast recommendations for a lager yeast, for instance, you will need to attemperate before direct pitching at lager temperatures. It's easier to simply rehydrate at a lower temperature, skip the attemperating step and live with the slightly lower viability that will result.

As far as I know, rehydration temperature has no effect on the fermentation profile that is not a consequence of its effect on yeast health, so the distinction on which your last question is predicated doesn't actually exist.


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## technobabble66 (1/9/16)

Lyrebird_Cycles said:


> .
> As far as I know, rehydration temperature has no effect on the fermentation profile that is not a consequence of its effect on yeast health, so the distinction on which your last question is predicated doesn't actually exist.


(Heritable) Epigenetics?

Ie: that the environment can dictate the genes that the organism activates, not just temporarily but potentially for the rest of its life, or the life of that particular cell (same thing here, with yeast). And then the potential for these changes to be inherited (sort of "hard-wired") in the future generation(s). 

Eg: rehydration at a higher temperature may impair that batch of yeast to produce an optimally clean/flavoursome fermentation (for beer production). 
Maybe a slightly lower rehydration temperature is the best compromise between optimal hydration conditions and optimizing the cleanest/appropriate flavour profile by that batch, as determined by the testing of the yeast manufacturers? 
EDIT: ie: the biochemistry/physiology of the yeast now becomes optimized for slightly lower temp conditions. 
I appreciate the vast majority of yeast care is all about optimizing their basic health & growth rate, and the concern I'm raising would be superfluous to that. However I'm curious as to why all the beer yeast manufacturers recommend temperatures well below what would initially appear optimal for rehydration. 
Also, my (basic) understanding of epigenetics would suggest there *might* be a need to compromise between conditioning for fermentation temps and optimal rehydration temps. 


Tbh, I find it hard to accept the "they've dumbed it down" explanation - there's not really a difference in effort between telling home brewers 27 or 33*c is what they need to achieve. I'm more inclined towards assuming they've got a better reason for it.


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## Lyrebird_Cycles (1/9/16)

technobabble66 said:


> Tbh, I find it hard to accept the "they've dumbed it down" explanation - there's not really a difference in effort between telling home brewers 27 or 33*c is what they need to achieve. I'm more inclined towards assuming they've got a better reason for it.


There is a difference: to get the benefit of using the higher temperature you have to include the attemperation which is A: an extra step and B: not called out on any of the sheets for brewing yeast I've seen.

This thread itself is testament to why the manufacturers would want to keep it as simple as possible.

Your argument from epigenetics is good if you are talking about cultures, culture conditions definitely affect yeast performance. Here we are talking about rehydration over a space of 15-20 minutes, I don't think that's enough time for anything significant to occur, this paper seems to agree with me.

To be clear: I am not certain about the applicability of wine protocols to brewing yeasts: if a manufacturer comes along and says "No, we did the tests, the temperatures we recommend are the optimal" you'd be wise to believe them. On the other hand I have tested for the most likely downside of using the higher temps and found no ill effects. YMMV etc etc.


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## BKBrews (1/9/16)

So I guess for us punters using the manufacturers guidelines, we should just go at the higher end of their recommended scale? e.g. re-hydrate US-05 in 30 degree water.


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## thefrothologist (1/9/16)

I rehydrate in 40˚C water based off data written in the Yeast book by Brewers Publications...(I think :-0)


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## kaiserben (1/9/16)

Interesting discussion! 

Fermentis suggested rehydration pitch temp is 27C +/- 3C (ie 24-30C)
Mangrove Jacks and Danstar are a bit higher at 32.5C +/- 2.5C. (ie 30-35C), nearly up at that 40C point that has been mentioned here. 

It might be worth noting that in a home brewing scenario that when you're pitching into water at a temp higher than room temp, that the temp will gradually fall during the 30 minutes you're rehydrating. The bigger the difference the more it will fall. Could falling temps affect the yeast?


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## BKBrews (1/9/16)

> Interesting discussion!
> 
> Fermentis suggested rehydration pitch temp is 27C +/- 3C (ie 24-30C)
> Mangrove Jacks and Danstar are a bit higher at 32.5C +/- 2.5C. (ie 30-35C), nearly up at that 40C point that has been mentioned here.
> ...


So maybe while a starter isn't exactly necessary for dry yeast, stir plates such as the yeast forge could help us to both a) gently stir the yeast (as advised to do by the manufacturers) and B) maintain pitching temp.


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## skb (1/9/16)

If nothing else there is no better brewing porn than a stir plate and starter in action... Makes my wife actually thinks I know what I am doing, so clearly a good smoke screen


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## rude (1/9/16)

kaiserben said:


> Interesting discussion!
> 
> Fermentis suggested rehydration pitch temp is 27C +/- 3C (ie 24-30C)
> Mangrove Jacks and Danstar are a bit higher at 32.5C +/- 2.5C. (ie 30-35C), nearly up at that 40C point that has been mentioned here.
> ...


I have wondered about this too

So next time might try the 40 c

To attemperate I pour my cube into FV then add wort to rehydrated yeast in the jar reducing temp at no more than 10 c 
I think , with 10min intervals I think they say


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## pcmfisher (1/9/16)

What is this thing called yeast you speak of?


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## rude (1/9/16)

Yeasts are eukaryotic, single-celled microorganisms classified as members of the fungus kingdom


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## Vini2ton (1/9/16)

100 ml of holy water per sachet in a zippy sandwich-bag, shoved in me jocks under me cassock is enough to get the little beggars going. Embarrassing during mass if the zippy gives way. I then blame Mrs Doyles cooking.


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