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I've always been rehydrating my dry yeast before pitching, but generally don't adjust temp before pitching. Do you guys try to slowly bring the slurry to the same temp as your wort before pitching? I normally ferment at about 18*c and the slurry would probably be about 25* at pitching time. Is this OK, or should I be trying to slowly bring the temp down by adding wort to the slurry?

I sprinkle dry yeast on oxygenated wort. Meh. Probably shouldn't do what I do

I never adjust temperature and always works fine. Sometimes I just throw the dry yeast in on the wort and it works fine that way too.

It's best to shock the yeast as little as possible, but I wouldn't worry about that much of a difference.

mr x wrote:It's best to shock the yeast as little as possible, but I wouldn't worry about that much of a difference.

That's pretty much what I was wondering. I've never noticed any issues with that I've been doing, but if I'm ever close on a pitch it's probably best to maximize yeast viability.

I wait till the water is around 26 or so and then set the yeast yo hydrate for 15 minutes. Normally I end up pitching at 22 degrees which is my basements temp and normally the wort. Never worried about it. I see it as, the environment my wort is at is equal to the yeast temp was as its all done in my basement.

CorneliusAlphonse wrote:I sprinkle dry yeast on oxygenated wort. Meh. Probably shouldn't do what I do

Interesting PDF study and synopsis from basic brewing radio April 14th 2011: http://hwcdn.libsyn.com/p/1/a/e/1aeeb08 ... 686e041d8a

Not sure but I think it answers Jimmy's question in the OP.

The conclusion:

Based on the described data it is recommended not to hydrate dry yeast since this may cause risks when not carried out in the proper way. Even when hydrating the yeast one might wonder what the benefit will be over the extra effort and risk.

also...

http://www.biabrewer.info/viewtopic.php ... ate#p30991

Yeast is killed or at least severely offended by most tap water.

I only found this out when I started making sourdough bread in the last few years. My teacher stressed that you must filter the water. Never before had I heard this advice on a brewing forum or in a brewing book. This is however the most basic and most important advice in looking after your bread yeast.

So, this one fact might explain several contradictions we have seen in the links above. One person re-hydrating with tap water just brought to the boil and cooled is probably killing half their yeast whilst another one re-hydrating their yeast with water that is totally chlorine-free will not be getting that problem. A person using warm water straight out of the tap will be getting the biggest problem of all.

http://www.beer.danstaryeast.com/freque ... -questions
I always aerate my wort when using liquid yeast. Do I need to aerate the wort before pitching dry yeast?

No, there is no need to aerate the wort but it does not harm the yeast either. During its aerobic production, dry yeast accumulates sufficient amounts of unsaturated fatty acids and sterols to produce enough biomass in the first stage of fermentation. The only reason to aerate the wort when using wet yeast is to provide the yeast with oxygen so that it can produce sterols and unsaturated fatty acids which are important parts of the cell membrane and therefore essential for biomass production.

I only use dry packs and I have not rehydrated or aerated my last few brews and they have all fermented (or are currently fermenting away) beautifully.

I'm pretty sure the book "Yeast" talks about why you should rehydrate yeast. I do see the point of doing it incorrectly will cause more harm than not rehydrating at all.


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Jayme wrote:I'm pretty sure the book "Yeast" talks about why you should rehydrate yeast. I do see the point of doing it incorrectly will cause more harm than not rehydrating at all.


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Yep, it does. Chris White mentions in the book that skipping the rehydration process and sprinkling the yeast directly on the wort kills about half of the pitched yeast cells.

I can't remember if he referenced studies, or are we supposed to do it because he says so. Also there is a huge difference between in vivo and in vitro experimentation. The two rarely correlate.

The study I posted a link to above compares brewing outcomes with rehydrated yeast vs pitched dry in real batches of beer. http://hwcdn.libsyn.com/p/1/a/e/1aeeb08 ... 686e041d8a

Guess I should put up as a caveat that since I'm only doing 1 gallon batches, and I also split the 11g dry yeast package in half, that 50 billion yeast cells is likely more than enough for my needs. Your mileage may vary.

Fermentis give’s you two options for US-05: I’m sure they have labs and scientists and access to research. They don’t mention that one option is preferable over the other.

http://www.fermentis.com/wp-content/upl ... A_US05.pdf

rehydration instructions

Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 27°C ± 3°C (80°F ± 6°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.

ps White doesn't say in the yeast book where he got that information about "skipping rehydration kills about half the cells pitched". I'm suspicious! Funny it's "about half" as well. It sounds like conjecture to me.

He is however one of the worlds leading experts on yeast... And I believe I heard him say in a podcast that the statement is based on his own research. About half is. Fair statement because there are many variables. If he stipulates an exact value, I would find that far more questionable.


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Jayme wrote:He is however one of the worlds leading experts on yeast... And I believe I heard him say in a podcast that the statement is based on his own research. About half is. Fair statement because there are many variables. If he stipulates an exact value, I would find that far more questionable.


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For sure he is an expert and a great asset to the brewing community. I was looking for more evidence before I considered re-hydrating. I did some more research and so far, on the home brewing scale at least, it seems that the benefits are minimal at most, and any potential benefits are outweighed by increased effort and risk.

Does anyone else sprinkle and not rehydrate? For what it's worth I am putting up my hand.

I have not rehydrated in many years, I have not noticed any ill effects.

Sandy

I pitch directly on the wort and get excellent results.

I do both ways. I prefer to rehydrate though. I'm pretty confident in my sanitation, so infection risks aren't a high concern to me.

I think there's also the risk of getting the rehydration procedure wrong and doing more harm than good. That's what worries me.

I usually rehydrate, but was lazy on my last brew and just sprinkled into the carboy. It was an ordinary bitter so lower gravity wort.

Same here, I usually rehydrate, but have sprinkled into the carboy on few occasions when I forgot to boil and cool some water. Will have to do a side by side comparison one of these days.

I got some Lallemand BRY-97 and they seem to be determined that you should rehydrate their dry yeast, yet their instructions (PDF attached) on how to do that make little sense to me and can be interpreted in a thousand different ways…for example what the hell does “then adjust temperature to that of the wort” mean. You are supposed to do that and then “inoculate without delay”. How do you “adjust temperature”… that sounds like you turn down a knob on the container, and then! as soon as that knob is turned down, there must be “NO DELAY” before you inoculate. It says "break up any clumps", and then in upper case letters DO NOT STIR, and then it says “suspend the yeast”. (those kind of instructions are reminiscent of conjecture to me).

Reminds me a bit of something OBK Patrick wrote once…

Poke it with a key or screwdriver or something to try to reseat the poppet. You are right it will not matter with a connect on. But the hissing should go away once pressure has equalized.

Oh yeah remember to boil your keys under a full moon for 45 minutes, not 44 or 46. Then sanitize it with the blood of a virgin mammoth before poking the poppet.

Someone posted after that comment that they had problems because they misread it and used the blood from a mammoth virgin instead....it's tricky to get this kind of stuff right.

I’ll try anything once (or twice), but how do people do this? Also looking for simple ways to do it all, avoiding contamination etc. Checking the temperature? “adjusting the temperature”? getting the amount of water right? (10x weight of dried yeast). What kind of container? How do you sanitise that container? (I’m worried that starsan might damage the yeast during rehydration) etc. I believe the water must also be free of chlorine.

Fermentis aren’t so particular with their US-05 instructions and give you the option to sprinkle if you want to. Are the Lallemand yeasts different in some way that they must be re-hydrated before pitching?

I boil some water (carbon filtered or with a small piece of a campden tablet) then put it in a mason jar (while still pretty much boiling) that I cleaned properly. You can pre-measure and mark a line on the mason jar to know how much to fill it too. I put some tin foil on top of the mason jar. Then I put the mason jar in a water bath to cool it down to about 30/40 degC (check with the yeast to know what temperature). You can easily check the temp of the water bath with a thermometer and add a bit of boiling water if you have to, and after an hour or so the temp of the water bath should be the same as the water inside the mason jar. Then you can add your yeast and wait 10 or 20 minutes, give it a swirl and pitch.

Tip: you can even boil the water inside the mason jar if you want to make sure it's sanitized.

I use a small erlenmeyer flask to boil the water. The rest is eyeballed.

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CartoonCod wrote:I boil some water (carbon filtered or with a small piece of a campden tablet) then put it in a mason jar (while still pretty much boiling) that I cleaned properly. You can pre-measure and mark a line on the mason jar to know how much to fill it too. I put some tin foil on top of the mason jar. Then I put the mason jar in a water bath to cool it down to about 30/40 degC (check with the yeast to know what temperature). You can easily check the temp of the water bath with a thermometer and add a bit of boiling water if you have to, and after an hour or so the temp of the water bath should be the same as the water inside the mason jar. Then you can add your yeast and wait 10 or 20 minutes, give it a swirl and pitch.

Tip: you can even boil the water inside the mason jar if you want to make sure it's sanitized.

+1, the boil will sanitize everything, including your thermometer