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New research on dry yeast

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Here is the latest US-05 spec sheet.
It doesn't mention wort aeration at all, I'm far from sure whether that means that they expect that
1/ any sensible brewer will have aerated their wort as a matter of course.
2/ It isn't necessary

They still recommend 50-80g/hl, at 23l, 50g/hl is 11.5g. No information is given on the effect of wort gravity so its pretty fair to assume that they are talking about "standard beer" (12oP and 25IBU (1.048)).

I suspect that if you aren't aerating you would want a bigger pitch rate to compensate, say up near the 80g/hl (~18.4g/23l). Good idea to pay very close attention to the recommended pitching temperatures to.
Mark
I used US-05 in my last batch and pitched into what I thought was a trifle high due to the ambient temp reading the range of pitching temperature put my mind at ease. I still do aerate my wort, maybe I should do a test which petru suggests aerate one batch and not another.
This is where I read about Fermentis suggesting not to aerate the wort.
https://discussions.probrewer.com/showthread.php?53010-Dry-yeast-needs-aerating-wort
 

razz

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I’ve been pitching dry yeast for years, us-05 and 34-70. And occasionally rehydrating with bugger all difference. Best thing I ever did was lift the pitch rate to minimum 1 g/l. And a bit more if I’m pitching cold.
 
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I’ve been pitching dry yeast for years, us-05 and 34-70. And occasionally rehydrating with bugger all difference. Best thing I ever did was lift the pitch rate to minimum 1 g/l. And a bit more if I’m pitching cold.
I have tried both methods razz the only thing I have found is the difference in lag time when rehydrated and pitched at similar temps.
 

razz

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No aerating of the wort Lorrisanga although I did have the yeast and water in a drink shaker and gave it a brief shake after rehydrating the yeast. I don’t recall a large difference in lag times Weal although that doesn’t mean there wasn’t. Always get some good action after 24 hours and generally hit TG at 5 days.
 

///

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Just for context, Whitey is a good mate of mine with a PhD related to yeast and fermentation. He is a respected teaching academic across the UC network, Master Brewers Assoc, Ibd and any other research and teaching facility you can poke a stick at for yeast. He has also has a solid working relationship with Lallemand (ahh, that dried yeast company) and sells some of thier products after working collaborately with them to develope the product.

Wobbly your academic or professional experience in brewing, fermentation scince and yeast is? Couple of research papers up your sleeve? BA, MSc, PhD?

I've been a practical brewer for 15 years and won Champion trophy's and medals following Whitey's advise.

Your post is personally and professionally offensive, bordering on slander to his reputation. It is one of, of not, the biggest peice of selling ejaculating Homebrewer bulllshit I have ever seen.

Yes, over reaction. Think twice before you post crap online.
 

peteru

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Yeah, sounds like a great idea...
Wait, no, you're saying to ignore what the manufacturer of the actual product has to say, and just perform a completely pointless, uncontrolled n=1 study...
I failed to convey sarcasm. Maybe I should have used the rolling eyes emoji.

There will always be people who don't believe in science. Heck, there are also people who like beer that I would tip out. If their yeast management produces beer that smells and tastes like green apple scented hand wash and they enjoy it, yay for them.

Correctly rehydrating dry yeast is such a simple and quick procedure that it makes you wonder why people resist doing it. It takes more effort to argue the point than just getting it done.
 

Vazerhino

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MHB (and others) - having read the Tips and Tricks - i don't understand why we need to re-hydrate outside the fermentation vessel as it says to rehydrate between 25 and 29 degrees. What is the difference in pitching in the fermenter at that temperature (thus "re-hydrating") versus wort in a separate vessel and then tipping into the fermenter?
 
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MHB (and others) - having read the Tips and Tricks - i don't understand why we need to re-hydrate outside the fermentation vessel as it says to rehydrate between 25 and 29 degrees. What is the difference in pitching in the fermenter at that temperature (thus "re-hydrating") versus wort in a separate vessel and then tipping into the fermenter?
When you read the tips and tricks in MHB's post it states re-hydrate in water, as I stated earlier that it could be a shock for the yeast to re-hydrate in a sugary wort.
 

MHB

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MHB (and others) - having read the Tips and Tricks - i don't understand why we need to re-hydrate outside the fermentation vessel as it says to rehydrate between 25 and 29 degrees. What is the difference in pitching in the fermenter at that temperature (thus "re-hydrating") versus wort in a separate vessel and then tipping into the fermenter?
The very short answer (short and incomplete) is that as the yeast is rehydrating it cant control what crosses the cell membrane and enters the cell.
If you rehydrate in other than water (ideally not distilled) the yeast can end up full of stuff that might not be good for it.
There has been a lot of research on this process that has lead to some commercial products like Go Ferm and a bunch of others. but these require spending time and money - been known to cause a terminal pucker among some home brewers....
Mark
 

JDW81

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The very short answer (short and incomplete) is that as the yeast is rehydrating it cant control what crosses the cell membrane and enters the cell.
If you rehydrate in other than water (ideally not distilled) the yeast can end up full of stuff that might not be good for it.
There has been a lot of research on this process that has lead to some commercial products like Go Ferm and a bunch of others. but these require spending time and money - been known to cause a terminal pucker among some home brewers....
Mark
As Mark rightly points out (as always), the issue with dehydrated yeast is it is unable to control what crosses it's cell membrane until it is rehydrated (I can't give you a timeframe).

The effect different solutions have on yeast depend on their toniticy/osmolarity/osmolality (whatever you want to call it) and the osmotic gradient between the cell and the fluid. There's a good podcast by the brewstrong guys on yeast rehydration.

Distilled water is hypotonic compared to the inside of the cell. If you rehydrate in distilled/deionised water, the yeast cells will swell and burst as the hypotonic solution moves into yeast cell.

Wort is hypertonic compared to the cell, and it will further dehydrate the yeast + shift intracellular solutes to ensure balance with the surround solution.

Good old fashioned tap water, while not truly isotonic, is pretty similar to the dehydrated yeast so it allows the yeast to rehydrate, while maintaining a fairly stable intracellular environment. Once's it's rehydrated properly, the cells can regulate what crosses the membrane and it can got to work and ferment your wort.

It is much more complicated that this, but this is a basic description of what happens.

JD
 

MHB

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I keep forgetting to say - make sure the water is de-Chlorinated - really we should all know that and its easy to assume people do.
Either carbon filter or boil your water before using it to rehydrate yeast, or grab a bottle of commercial water(not mineral water), most of them are just filtered tap water.
About the worst thing that can get inside a yeast cell is any free halogen (F, Cl, Br, I) lots of other stuff that isn't good but halogens are probably the worst your likely to have in your tap water.
M
 

labels

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Pray tell me I'm doing everything wrong.
I run a starter on all yeast whether dry or liquid on a stir plate with a 1.040 starter wort made from DME. Much bigger starters with lagers but still 1.040. Generally, the starter is kept at 25-30C, lager or ale.

I start with 500ml - 1L of wort per pack of yeast, usually three-four days before brewing and this ferments out fairly quickly. The night before brewing I step up again with about 500ml DME starter wort per pack of yeast. The stir plate is turned up to high with a big vortex.

When pitching, I do not throw away the starter beer, it's kept spinning hard on the stir plate so I am pitching highly oxygenated, yeast rich beer into my wort. Even with lagers, lag time is almost zero and I pitch all beers at 25-30C. In all cases they go directly into my temp controlled chest freezer and hit ferment temps well within 12 hours (we're talking about 100L brews divided into four 30L fermenters)

Being I brew mainly lagers, they come out very clean and free of all fermentation by-products every time.
 

krz

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....

Your post is personally and professionally offensive, bordering on slander to his reputation. It is one of, of not, the biggest peice of selling ejaculating Homebrewer bulllshit I have ever seen.

Yes, over reaction. Think twice before you post crap online.
Which post do you refer to /// that is offensive.
I looked through the history but cant see what was offensive, maybe it was deleted?
 

Brewno Marz

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Pray tell me I'm doing everything wrong.
I run a starter on all yeast whether dry or liquid on a stir plate with a 1.040 starter wort made from DME. Much bigger starters with lagers but still 1.040. Generally, the starter is kept at 25-30C, lager or ale.
I would say you’re not doing anything wrong. It works for you. For me, I have just started direct pitching dry yeast into the wort based on this thread and found it reduces lag time and reduces time to FG compared with rehydrating, especially for lagers (e.g. w34/70 ot MJ-84). Note that I haven’t made starters from dry yeast though, and don’t intend to, so can’t comment on additional benefits outlined by @labels . I had been rehydrating dry yeast for decades and now question why I spent this extra time and effort. All anectdotal though, so each to there own...
 

altone

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Pray tell me I'm doing everything wrong.
I run a starter on all yeast whether dry or liquid on a stir plate with a 1.040 starter wort made from DME. Much bigger starters with lagers but still 1.040. Generally, the starter is kept at 25-30C, lager or ale.

...

Being I brew mainly lagers, they come out very clean and free of all fermentation by-products every time.
I basically do the same except at a lower temp (20-25 - room temp)

Wort is hypertonic compared to the cell, and it will further dehydrate the yeast + shift intracellular solutes to ensure balance with the surround solution.
Bugger! But I assume as we are actually making a starter the yeast recovers and propagates as usual.
I do actually start off with a low gravity wort - perhaps that reduces the shock.
 

Coalminer

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I run my ale starters at 26-27C (which is the same as the recommended rehydration temps),
but slowly reduce the starter to the wort pitching temps before pitching, generally 17-18C
 

5teve

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I've always read and understood to just rehydrate using only sterile water, but in the latest US-05 spec sheet linked by MHB in the pitching with prior rehydration instructions it says "Alternatively, sprinkle the yeast in minimum 10 times its weight of sterile water or boiled and hopped wort..."

Also in the "How to rehydrate yeast?" section in the linked Tips and Tricks brochure, they also state "Fermentis yeast can be rehydrated with sterile water or sterile wort,..."

There's no clear indication by them that water is the recommended choice anymore?
 
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I've always read and understood to just rehydrate using only sterile water, but in the latest US-05 spec sheet linked by MHB in the pitching with prior rehydration instructions it says "Alternatively, sprinkle the yeast in minimum 10 times its weight of sterile water or boiled and hopped wort..."

Also in the "How to rehydrate yeast?" section in the linked Tips and Tricks brochure, they also state "Fermentis yeast can be rehydrated with sterile water or sterile wort,..."

There's no clear indication by them that water is the recommended choice anymore?
I think they purposely do that, imagine the thousands of pairs of eyes on many amount of threads on many forums where the name Fermentis crops up. Buckshee advertising.;)
 
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