Dry yeast - do not rehydrate?

[dsaavedra]

I have a kit (Brewer's Best Irish stout I believe) and the instructions explicitly say, in all caps "DO NOT REHYDRATE THE YEAST". I think it may even say that on the yeast packet as well. What's up with this? I thought it was generally better to rehydrate with warm water before pitching dry yeast. On my first batch I just pitched dry but I think in the future I would like to rehydrate, but these instructions just confused me.

 

[jtratcliff]

Hmmm... Yeah. Not sure here. You're probably OK either way (unless your OG was WAY high). Dry packets usually have enough cells for a direct pitch into a typical beer.

For "proper" yeast health, rehydration is probably better.

Rehydration won't hurt anything.

 

[AgentHubcap]

I almost never rehydrate my yeast if that makes you feel any better

Sent from my Nexus 5 using Home Brew mobile app

 

[RM-MN]

Is this the first time you've seen something that is obviously wrong in print? Seriously, studies have been done that show that up to half the yeast cells in that packet will die if pitched directly into wort while nearly all survive if rehydrated first. I try to remember to rehydrate my dry yeast every time now.

 

[boydster]

Read the results of these experiments and make the decision you think is right:

http://seanterrill.com/2011/04/01/dry-yeast-viability/
http://seanterrill.com/2011/07/29/dry-yeast-viability-take-two/
http://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/

FWIW, I choose to rehydrate. It's easy.

 

[titansvol]

I would always rehydrate dry yeast.

 

[Clonefan94]

Why not call or email Brewer's Best and ask them? Maybe they have a good reason, maybe they don't, but I usually defer to the source first, when trying to find something out.

I'll admit, it seems odd, especially with the info out there on weather or not to re-hydrate the yeast, but they might have a good explanation that none of us know about.

If they don't give you a good reason, then I would re-hydrate.

 

[BigFloyd]

Sometimes, kit instruction sheets in general leave a lot to be desired.

I believe that Brewer's Best also instructs you (wrongly) to leave the beer just one week in the primary and then rack it to a secondary for two weeks. I also wouldn't be surprised if their pitch and ferment temperature instructions may be on the high side. My take on Brewer's Best kits (which are the brand my LHBS carries) is good ingredients, but questionable instructions.

 

[JLem]

It is generally best to rehydrate dry yeast UNLESS you cannot do so sanitarily. Not rehydrating removes one place where contamination might be introduced...it is my belief that beginner instructions do not recommend rehydrating because it keeps things simpler. That said, I do not know why any instructions would actually recommend NOT rehydrating...unless I suppose there is a desire for some flavor profiles that might arise from underpitching???

 

[DJPalenchar]

My BB chocolate milk stout said the same thing

 

[nicklepickles]

Ya know, I believe BYO did a study about this some time ago. They tested the same wort twice, the only variable being rehydrating vs not rehydrating the dry yeast before hand. As I believe, absolutely no difference was found. In my own experience as well, all my beers with dry yeast have been fine (if not downright delicious), never rehydrated it. As i see it, rehydrating is just anoter chance to make a mistake and kill your yeast if you aren't careful enough

 

[max384]

Rehydrating may be better, but I've never had any undesirable effects from pitching dry yeast... So, for me, why try and fix what isn't broken?

 

[boydster]

It would be pretty hard to kill your yeast by rehydrating, even if you aren't being careful. They'll survive water temps upwards of 130F+. By not rehydrating, you're taking that "chance" of killing your yeast and turning it into a certainty for a large percentage of the cells in the packet - it's been shown time and time again.

But it really boils down to: is pitch rate an important thing to be concerned with? I've made beer without rehydrating dry yeast and I've made beer without making a starter using liquid yeast and thought the results were great - when I first started, I didn't know any better. Making those same recipes and being more conscious of my pitch rate has, IMO, made those beers even better. If you feel like pitch rate is important, you are probably the type of person who rehydrates dry yeast and makes starters with liquid yeast. If you don't feel pitch rate is a big deal, you are probably in the crowd that doesn't rehydrate or make starters. To each, their own. There's only one person you need to worry about pleasing with the beer you brew, and that's yourself.

With as much time and energy as I put into creating a recipe, purchasing quality ingredients, brewing, and waiting to finally enjoy the fruits of my labor, I think taking 30 minutes to rehydrate dry yeast while my wort is chilling is a no-brainer.

 

[nicklepickles]

It would be pretty hard to kill your yeast by rehydrating, even if you aren't being careful. They'll survive water temps upwards of 130F+. By not rehydrating, you're taking that "chance" of killing your yeast and turning it into a certainty for a large percentage of the cells in the packet - it's been shown time and time again.

But it really boils down to: is pitch rate an important thing to be concerned with? I've made beer without rehydrating dry yeast and I've made beer without making a starter using liquid yeast and thought the results were great - when I first started, I didn't know any better. Making those same recipes and being more conscious of my pitch rate has, IMO, made those beers even better. If you feel like pitch rate is important, you are probably the type of person who rehydrates dry yeast and makes starters with liquid yeast. If you don't feel pitch rate is a big deal, you are probably in the crowd that doesn't rehydrate or make starters. To each, their own. There's only one person you need to worry about pleasing with the beer you brew, and that's yourself.

With as much time and energy as I put into creating a recipe, purchasing quality ingredients, brewing, and waiting to finally enjoy the fruits of my labor, I think taking 30 minutes to rehydrate dry yeast while my wort is chilling is a no-brainer.

1) at 130 F, your yeast is dead. Typically, yeast cells cant survive above about 100F or so. 130F an upwards is definitely killing your yeast if you rehydrate that hot. Safale/lager/brew specifically say to "sprinkle on wort", i.e. don't rehydrate.

2) pitch rate has nothing to do with rehydration. You aren't increasing cell count by rehydrating, just getting the yeast "ready". Im always making sure im pitching enough yeast, but never bother rehydrating. Pitching rate is absolutely important, however. Don't pitch enough cells and you are going to get a drastically different beer in the end.

With all the time i spend putting recipes together and getting top quality ingredients and yeast, i will never bother chancing killing my yeast by rehydrating.

But, as with all things, YMMV, and to each their own.

 

[JLem]

1) at 130 F, your yeast is dead. Typically, yeast cells cant survive above about 100F or so. 130F an upwards is definitely killing your yeast if you rehydrate that hot. Safale/lager/brew specifically say to "sprinkle on wort", i.e. don't rehydrate.

2) pitch rate has nothing to do with rehydration. You aren't increasing cell count by rehydrating, just getting the yeast "ready". Im always making sure im pitching enough yeast, but never bother rehydrating. Pitching rate is absolutely important, however. Don't pitch enough cells and you are going to get a drastically different beer in the end.

With all the time i spend putting recipes together and getting top quality ingredients and yeast, i will never bother chancing killing my yeast by rehydrating.

But, as with all things, YMMV, and to each their own.

I can't really comment on the temperature thing, but I am pretty certain yeast can tolerate temps greater than 100F - how much? Not sure.

As for the cell count thing...rehydrating definitely increases cell count - not because it results in any growth during rehydration, but because it prevents up to 50% cell death when the yeast are sprinkled onto the wort directly - as you mentioned, rehydrating gets the cells ready...if they are not ready the have a hard time dealing with the osmotic shock of being dropped into wort.

Also, homebrew packets of dry yeast may say to sprinkle directly on wort, but the professional instructions (which can be found online) for these exact same yeast give explicit instructions on how to rehydrate. I believe the packets do not do this for the same reason i mentioned above - it's simpler and removes one step where an inexperienced brewer could introduce contamination.

I'm not suggesting that you can't make great beer if you dont rehydrate or that everyone MUST rehydrate. Personally, I feel that the costs of rehydrating are minimal compared to the potential benefit, so I rehydrate. If you think the potential costs of rehydrating outweigh the potential benefits, then you should not rehydrate.

 

[boydster]

1) at 130 F, your yeast is dead. Typically, yeast cells cant survive above about 100F or so. 130F an upwards is definitely killing your yeast if you rehydrate that hot. Safale/lager/brew specifically say to "sprinkle on wort", i.e. don't rehydrate.

2) pitch rate has nothing to do with rehydration. You aren't increasing cell count by rehydrating, just getting the yeast "ready". Im always making sure im pitching enough yeast, but never bother rehydrating. Pitching rate is absolutely important, however. Don't pitch enough cells and you are going to get a drastically different beer in the end.

With all the time i spend putting recipes together and getting top quality ingredients and yeast, i will never bother chancing killing my yeast by rehydrating.

But, as with all things, YMMV, and to each their own.

1) Not true. 100F doesn't kill brewer's yeast. Where did you hear that?

2) Rehydrating does everything to do with pitch rate. If 50% of the cells die (this has been shown repeatedly) then it affects your pitch rate.

 

[kh54s10]

1) at 130 F, your yeast is dead. Typically, yeast cells cant survive above about 100F or so. 130F an upwards is definitely killing your yeast if you rehydrate that hot. Safale/lager/brew specifically say to "sprinkle on wort", i.e. don't rehydrate.

If you go to the websites of the dry yeast manufacturers you will find that they do recommend rehydrating. Why they print otherwise on the package is ?????

2) pitch rate has nothing to do with rehydration. You aren't increasing cell count by rehydrating, just getting the yeast "ready". Im always making sure im pitching enough yeast, but never bother rehydrating. Pitching rate is absolutely important, however. Don't pitch enough cells and you are going to get a drastically different beer in the end.

I would still recommend rehydrating. But occasionally I don't and the beer has turned out good. How much better if it was rehydrated???

With all the time i spend putting recipes together and getting top quality ingredients and yeast, i will never bother chancing killing my yeast by rehydrating.

But, as with all things, YMMV, and to each their own.

It is pretty commonly accepted that you ARE killing yeast cells if you do not rehydrate. How much difference this makes is debatable.

YMMV

 

[nicklepickles]

alright, clearly im out numbered here, so im not going to try to argue that rehydrating increases cell count (how does NOT killing INCREASE number? theres no sugar, no fermentation going on, thus no cell division, thus no growth).
Also, since when is it exactly 50% less cell health if not rehydrating? ive been looking in to this subject for awhile, this is literally the first place ive seen that number.

kh54s, asking rhetorical questions does not prove your point. it was once commonly accepted the earth was flat...

boydster, ive heard 100 F mostly with repect to wine yeasts (where rehydrating with a nutrient DEFINITELY helps), assumed there would be a good bit of crossover with dry beer yeasts. Also, "IF" being the key word, 50% is a HUGE "if".

JLem, i literally just looked at my s-05 pack, says to sprinkle. however, the website says
"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"

They recommend rehydrating a good bit lower then what standard instructions say, and also seem to imply you can pitch directly, if you do it in a stepped, controlled manner. Im thinking the difference in the two recommendations is because the small packets are for smaller, home use and the internet instructions are for larger, commercial use. I have no idea though.

alright, rantings now turned off

 

[boydster]

Look at the results of the experiments I posted earlier and draw your own conclusion. That is empirical data, not anecdotal experience. No one is saying rehydrating in water increases cell count. What I am saying is rehydrating in wort decreases cell count. That's all. I'm going to go drink a beer now.

 

[max384]

alright, clearly im out numbered here, so im not going to try to argue that rehydrating increases cell count (how does NOT killing INCREASE number? theres no sugar, no fermentation going on, thus no cell division, thus no growth).
Also, since when is it exactly 50% less cell health if not rehydrating? ive been looking in to this subject for awhile, this is literally the first place ive seen that number.

kh54s, asking rhetorical questions does not prove your point. it was once commonly accepted the earth was flat...

boydster, ive heard 100 F mostly with repect to wine yeasts (where rehydrating with a nutrient DEFINITELY helps), assumed there would be a good bit of crossover with dry beer yeasts. Also, "IF" being the key word, 50% is a HUGE "if".

JLem, i literally just looked at my s-05 pack, says to sprinkle. however, the website says
"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"

They recommend rehydrating a good bit lower then what standard instructions say, and also seem to imply you can pitch directly, if you do it in a stepped, controlled manner. Im thinking the difference in the two recommendations is because the small packets are for smaller, home use and the internet instructions are for larger, commercial use. I have no idea though.

alright, rantings now turned off

I sprinkle dry yeast instead of rehydrating, so I'm with you there... But to answer your question I bolded:

Imagine that you are pitching a ficticious 100 yeast cells. Lets agree for the sake of argument that half of them will die when they are pitched directly on the wort dry. That leaves you with 50 viable yeast cells to multiply and ferment. If we rehydrate those same 100 yeast, we'll agree for the sake of argument that half of them won't die. Thus, when the rehydrated yeast are pitched, all 100 of them will be available to multiply and ferment.

So, in reality, 100 yeast cells were pitched in both instances. However, in the case of the dry yeast, half of the cells would die very soon after pitching, thus the practical number of yeast cells pitched were about 50. So, rather than look at rehydrating yeast as increasing cell count, it would be best to look at NOT rehydrating yeast as decreasing viable cell count.

 

[LLBeanJ]

For those who are wondering what the source is for the 50% cell loss if not rehydrated:

From Yeast by White & Zainasheff (p. 146):

"While most commercial brewers rehydrate their dry yeast before pitching, most homebrewers just sprinkle the dry yeast on top of their wort. Perhaps they read it in a book, or their local expert told them rehydration was not necessary. Technically the beer will ferment if you pitch enough nonrehydrated yeast, but you are not giving the yeast an opportunity to make the best beer possible. Skipping rehydration kills about half the cells pitched. Besides only having half as much yeast as is needed, the dead cells immediately begin to break down and affect the beer flavor. Why would anyone recommend skipping rehydration? For the same reason you would avoid making a starter: Your process is either unsanitary or damaging to the yeast health. Even if you do rehydrate the yeast, you can easily kill it if you are lax in monitoring the water temperature. If your rehydration process introduces significant amounts of bacteria or wild yeast, perhaps you would be better off not employing the extra steps until you can master the process in a sanitary way. It is situations like this where an expert might advise skipping rehydration and just adding more yeast to make up for the loss of viable cells."

 

[jekeane]

My Brewers Best American Cream Ale Said NOT to rehydrate on the included instructions. The Nottingham Yeast package included with the kit had the instructions to rehydrate on the back. From what I have read rehydrating is always preferred. I think a lot of times the "easy" level kits try to skip as many steps as they can so you will be guaranteed to get an ok beer do to less user error. However if you do things the right way ie rehydrate your yeast, use extra extract rather than corn sugar you can get a better beer.

 

[DeBAD]

Is this the first time you've seen something that is obviously wrong in print? Seriously, studies have been done that show that up to half the yeast cells in that packet will die if pitched directly into wort while nearly all survive if rehydrated first. I try to remember to rehydrate my dry yeast every time now.

+1 infinity!

 

[BigFloyd]

My Brewers Best American Cream Ale Said NOT to rehydrate on the included instructions. The Nottingham Yeast package included with the kit had the instructions to rehydrate on the back. From what I have read rehydrating is always preferred. I think a lot of times the "easy" level kits try to skip as many steps as they can so you will be guaranteed to get an ok beer do to less user error. However if you do things the right way ie rehydrate your yeast, use extra extract rather than corn sugar you can get a better beer.

Did the Brewers Best instructions also give you a fermentation temp range that indicates that it's OK to ferment with Notty above 68*F? If so, that's another big strike against their kit instructions.