Dry yeast does not require rehydration and also does not require aeration

[Northern_Brewer]

Clayton Cone, long-time yeast guru at Lallemand, explains it a bit here (even if I misremembered the numbers, I've corrected them in my post) : http://www.hbd.org/hbd/archive/3301.html#3301-4

Note that does date back to 2000, when manufacturing processes were rather different, so concentrate on what he says about biology rather than the specifics of rehydrating particular yeast.

The whole LODO thing gets complicated if you try to take it too far, as you also have to consider things like CO2 toxicity, which is reduced by aeration. You can also contribute more lipids to the wort in the form of dead yeast (as Cloudwater do) etc.

 

[Silver_Is_Money]

The only other source I came across was the podcast I mentioned. But now I can't seem to find it.

 

[TasunkaWitko]

I don't have a dog in the fight, but I do know that I have never rehydrated my dried yeast; I have always simply filled the fermenter, pitched the yeast, put a lid on the fermenter, and then agitated it (the fermenter) for 3 to 5 minutes. I have never had a single yeast failure, and I have never had oxygenated beer.

Having said that, I think that rehydrating the yeast should and would be a good practice; I simply don't do it.

 

[TasunkaWitko]

I agree. A lot of what is going on is a lot of overthought.

Ever shingle a roof with 3 tab shingles?
You know that thin piece of clear cellophane plastic on the back of each and every shingle ?
A lot of people think that needs to be removed before you nail it down. It doesn't .
Its only purpose is to keep the shingles from sticking together in the bundle because warehouses are hot . if this piece was not there the entire bundle would be a huge block after a few hours, if a shingle was attempted to be removed , it would more than likely rip,leaving it damaged and useless. But, someone somewhere had no idea of this and thought it helps the shingles stick together on the roof if they removed it. Can't tell you how many houses Ive driven past and heard and see all these plastic strips blowing off the roof .
Ignorance and overthought are an interesting combination.

I miss T-locks. They were perfect for windy, north-central Montana.

 

[mabrungard]

when you say the wort is at lager temperatures , are you fermenting at lager temperatures ?? Do you ferment at the optimal temperature on the yeast packet?

Sure, I ferment a lager at lager temperature. This was with 34/70 dry yeast.

 

[BrewnWKopperKat]

Clayton Cone, long-time yeast guru at Lallemand, explains it a bit here (...) : http://www.hbd.org/hbd/archive/3301.html#3301-4

Note that does date back to 2000, when manufacturing processes were rather different, so concentrate on what he says about biology rather than the specifics of rehydrating particular yeast.

Interesting read (thank you!).

Here's a big Fermentis presentation on the matter

Interesting read as well. Thank you

This ("Dry Yeast Rehydrate vs Non-Hydrate Lab Results in Wort") may also be of interest for those who are interested the dehydration / rehydration process.

Trusting yeast lab / maltster information then validating it with taste preferences seems like a good way to brew (especially if manufacturing processes improve over time).

 

[mediant]

This ("Dry Yeast Rehydrate vs Non-Hydrate Lab Results in Wort") may also be of interest for those who are interested the dehydration / rehydration process.

Another one from University of Nottingham and Lallemand - Stress, Viablity and ADY

 

[BrewnWKopperKat]

Another one from University of Nottingham and Lallemand

I had time to skim it over lunch - thank you! I'll give it a deeper read over the next week or so.

 

[enkamania]

I don't go out of my way to aerate, I just pump the wort in the fermenter and that has worked for liquid yeast. Not sure how I would stop aeration.

 

[Vale71]

Dried yeast are stuffed with sterols, about 5% lipids compared to 0.7% in normal yeast. So the first generation will have 2.5%, 2nd generation 1.25%, 3rd generation .625%. So dried yeast can ~8x in numbers without oxygen, which is not far off the 10x-ish that is normal in the typical homebrew setup.

And of course, not having to add oxygen is of particularly interest if you're taking the low-oxygen route to protecting hoppy beers or lagers from oxidation.

Edit - fix numbers

Also to consider is that when aerating wort any dissolved oxygen will be entirely taken up by 1st generation cells anyway. Yeast absorbs available oxygen in a really short time, by the time the lag phase is over and reproduction actually starts there is no more DO and subsequent generations will have to rely on sterols that they received when they were spawned by their mother cells anyway.
I won't comment on the manufacturer's claims that dry yeast has as many sterols in reserve as liquid yeast pitched into aerated wort will achieve, but if they are true then there really would be no point in aerating when pitching dry yeast.

 

[Silver_Is_Money]

If the manufacturers of dry yeast recommend revised instructions that ultimately give inferior results their sales will eventually suffer simply via negative word of mouth (such as on forums like this one) from dissatisfied end users. This logic leads me to believe that their confidence is rather high that they are offering good advice.

 

[jhembro13]

P

 

[Neoreaver]

CO2 and alcohol. how many people oxygenate their bread dough??? thats right, none.

Literally anyone who has proofed dough doesn't do so in a sealed, airtight container. Those yeasties are pulling O2 like mad.

 

[Big Monk]

And of course, not having to add oxygen is of particularly interest if you're taking the low-oxygen route to protecting hoppy beers or lagers from oxidation.

Oxygen come pitching time is not a problem for a low oxygen beer but I agree that not having to add any at all is a plus.

 

[Soulshine2]

Sure, I ferment a lager at lager temperature. This was with 34/70 dry yeast.

the reason I asked is that fermentation and lagering are two separate events,usually at two different temperatures. I've used 34/70 before.

 

[applescrap]

Thanks Silver appreciate the data.

 

[Silver_Is_Money]

Lallemand has amended their advice. At 16 Plato and above (1.065 SG and above) rehydration and aeration are advised. Below that they are not necessary.

https://www.lallemandbrewing.com/docs/products/bp/BEST-PRACTICES_REHYDRATION_DIGITAL.pdf

 

[madscientist451]

Some dry/rehydrated experiments with results:

https://www.beeradvocate.com/community/threads/a-dry-yeast-rehydration-experiment.601466/

http://brulosophy.com/2014/09/15/sprinkled-vs-rehydrated-dry-yeast-exbeeriment-results/

So it looks like you can sprinkle the dry yeast in or re-hydrate, it doesn't make that much difference. Note that there doesn't seem to be any downside to re-hydrating except the extra effort.
The only dry yeast I've used recently is wine yeast used in mead and cider. I'm guessing that wine yeast still has to be re-hydrated for mead? On the back of a pack of 71-b it says: "re-hydrate before use".

 

[tellyho]

Do you have a link to anything that would explain this further? I want to explore this. It's the only time I can recall seeing anyone give a reason why oxygenating isn't necessary, and backing it up with some numbers.

And, FWIW, you've hit on one of the reasons why I care: LODO. If I can pitch dry yeast without oxygenating the wort, I'm not oxidizing the flavors that are there. Further, if the yeast are already packed with sterols, then I'm guessing they aren't metabolizing the oxygen I've just added to the wort, which extends the time during which oxidizing flavors can occur.

I have NEVER oxygenated my wort. Been making it for 13 years.

 

[Vale71]

And, FWIW, you've hit on one of the reasons why I care: LODO. If I can pitch dry yeast without oxygenating the wort, I'm not oxidizing the flavors that are there. Further, if the yeast are already packed with sterols, then I'm guessing they aren't metabolizing the oxygen I've just added to the wort, which extends the time during which oxidizing flavors can occur.

Yeast absorb oxygen through diffusion, which means they have no means of throttling or otherwise controlling the rate of oxygen intake. Besides that, oxygen is used not just for sterol synthesis but also for respiratory metabolism of carbohydrates which is much more efficient than ethanol fermentation. The only situation where you have to worry about yeast not metabolizing oxygen is if you actually pitched dead yeast.

 

[mongoose33]

Yeast absorb oxygen through diffusion, which means they have no means of throttling or otherwise controlling the rate of oxygen intake. Besides that, oxygen is used not just for sterol synthesis but also for respiratory metabolism of carbohydrates which is much more efficient than ethanol fermentation. The only situation where you have to worry about yeast not metabolizing oxygen is if you actually pitched dead yeast.

That's good to know, but here's the question: how soon do they start the oxygen takeup? It would seem if they're already packed with sterols and such, that they're still going to be slower taking it up than if they weren't, and meanwhile, it's oxidizing the wort flavors. At least theoretically. Or is that incorrect thinking?

This is an interesting question; I think I need to be looking at buying a DO meter. I have a sampling port on my conical, I could fairly easily do some assessments of this.

Any idea as to a good DO meter? I know I'm probably looking in the $400 or maybe more area. Would have a hard time justifying $1k for one, but half that I could do. I have some spousal goodwill I could apply to that.

 

[Vale71]

Yeast is really efficient in uptaking oxygen and will store any excess O2 in the mitochondria for later usage. At normal oxygenation levels if the yeast is mixed thoroughly in the wort you should not be able to detect any DO in a matter of minutes.
Here is a cheap DO meter from China. I have no idea about its precision or reliability as I haven't bought one myself yet.

https://www.aliexpress.com/item/329...96-41ea-973a-3fc5735c95c7&transAbTest=ae803_4

 

[Nemanach]

Are Safale and Fermentis packaged the same? If they are then could we treat Safale US-05 the same and get the same results? I use US-05 on IPAs and I’m wondering if skipping oxygenation will help retain more hop aromas.

Edit: Nevermind, Fermentis makes Safale. They are the same.

 

[Jag75]

I've never rehydrated dry yeast. When I first started I never even aerated the wort either . Sometimes I just sprinkle the yeast onto the wort and close up . Sometimes I've stirred it up real good. Never noticed any difference tbo.

 

[Mer-man]

That's good to know, but here's the question: how soon do they start the oxygen takeup? It would seem if they're already packed with sterols and such, that they're still going to be slower taking it up than if they weren't, and meanwhile, it's oxidizing the wort flavors. At least theoretically. Or is that incorrect thinking?
....

Well if you rehydrate them, they'll be active and able to take up any supplemental O2 you provide. Then you're building on the sterol /nutrient levels built in. I recently had excellent performance with a pack of US-05 in a high gravity wort that I hit with pure O2.

But if you use pure O2 and just pitch unrehydrated yeast, then you're oxidizing your wort for 15-30 minutes while the yeast rehydrates. So if I were to pitch unrehydrated yeast, I would not aerate/oxygenate. In that scenario, you only have the 15-30 minute window of atmospheric on the surface area.

 

[ten80]

But if you use pure O2 and just pitch unrehydrated yeast, then you're oxidizing your wort for 15-30 minutes while the yeast rehydrates. So if I were to pitch unrehydrated yeast, I would not aerate/oxygenate. In that scenario, you only have the 15-30 minute window of atmospheric on the surface area.

Agreed, no sense in wasting pure O2 while your yeast is rehydrating and exposed to oxygen in the carboy headspace. You can add O2 once the yeast is actively bubbling away in the first ~24 hrs for a big beer (>1.100 OG) where you want to give the yeast a boost by promoting sterol synthesis.

However, I have had great luck with Safale's dry yeasts and no oxygenation for beers up to 1.120 and beyond. BE-256 in particular will ferment to 16-18% ABV without oxygenation if you ramp temperature gradually and agitate the carboy periodically. In my case, I pitched 2 rehydrated packets for 5 gallons of 1.115 and fed sugars as the fermentation progressed for an adjusted gravity of around 1.165. I don't think liquid yeast would have done as well in this case.

 

[rtstrider]

Feel like I'm beating a dead horse, but once again.

I've emailed them about this and got reply that they have done 0 sensory analysis on this, everything is measured by machines. I mailed them because I have one regular beer I brew and if I rehydrate the pack its pretty darn boring, if I just sprinkle the yeast it lands where it should tastewise with phenols. I've tried this several times, same difference every time. A friend of mine has experienced the exactly same.

The way I discovered this was that the first time I made it I got lazy and just sprinkled it, second time I wasn't as lazy and rehydrated it, and noticed a big difference. So i started testing.. Same batch of yeast, no added oxygen.

If someone want to try the recipe, twice (or split-batch), I can share it since it's a yeast-driven recipe. It's a nice fresh ale for sunny days. It would be fun to see if more people experience this.

What is your fermentation vessel? I had the same exact problem with us-05 repitches. Come to find out it was the fermenter

 

[Gregory T]

I am using dry yeast for the first time in a Belgian Blonde. I pitched 3 packs, 1 T-58, 1 BE-256, and 1 Abbaye. I did not rehydrate and the only aeration was from my venturi I made in the hose I drain from Bk to fermentor.

We shall see how it turns out. It was very active with a few hours

 

[JAReeves]

In practice, the consecutive steps for direct pitching are:

• Fill the fermenter with 1/3 of the wort volume (up to the top of the CKT cone) at a temperature of 21-29 °C
• Sprinkle the active dry yeast cells directly in the fermenter
• Add the remaining 2/3 of the volume of wort at fermentation temperature to allow for mixing of yeast and wort.

Anyone actually doing this?

Cheers!

This may be SOP and redundant, but I pour my cooled wort through a strainer and funnel setup into the fermenter. I sprinkle the dry yeast or pour the liquid yeast into the strainer first and let the wort wash the yeast into the fermenter while it oxygenates and mixes. Fastest krausen was in 4 hours, slowest was in 12 or so.

 

[cswant88]

I direct pitched a pack of us-05 last night. One pack, 1.057 OG. I did aerate slightly by lifting the transfer hose up above the wort level and let it splash around a bit. The lag phase was a bit longer than I’m used to, but I’ve got krausen and airlock activity starting now. Can’t wait to see how it turns out.

FYI, yeast was relatively “fresh”. Expiration 02/2022

 

[ncbrewer]

In practice, the consecutive steps for direct pitching are:

• Fill the fermenter with 1/3 of the wort volume (up to the top of the CKT cone) at a temperature of 21-29 °C
• Sprinkle the active dry yeast cells directly in the fermenter
• Add the remaining 2/3 of the volume of wort at fermentation temperature to allow for mixing of yeast and wort.

Anyone actually doing this?

Cheers!

This procedure isn't practical for me. By not following their best practices, I would be voiding their recommendation to dry pitch, so I continue to rehydrate.

 

[BrewnWKopperKat]

In practice, the consecutive steps for direct pitching are:

• Fill the fermenter with 1/3 of the wort volume (up to the top of the CKT cone) at a temperature of 21-29 °C
• Sprinkle the active dry yeast cells directly in the fermenter
• Add the remaining 2/3 of the volume of wort at fermentation temperature to allow for mixing of yeast and wort.

Anyone actually doing this?!

If I had a CKT cone, I'd certainly give it a try.

This simpler process works well for me:

Pitch the yeast directly in the fermentation vessel on the surface of the wort at or above the fermentation temperature. Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available to avoid clumps.

Sprinkle it, re-hydrate it, make a starter (because dry yeast is expensive in your area or because it ships better in the summer or because it seems like a fun thing to do or ... ).

Just remember to pitch the yeast.

 

[smata67]

If I had a CKT cone, I'd certainly give it a try.

This simpler process works well for me:


Sprinkle it, re-hydrate it, make a starter (because dry yeast is expensive in your area or because it ships better in the summer or because it seems like a fun thing to do or ... ).

Just remember to pitch the yeast.

I'm going to go out on a limb here and agree that forgetting to pitch the yeast might possibly have adverse effects on the end result, namely, the creation of beer. .

 

[Edward's Beer Cellar]

I'm a little late to this thread and a relatively new brewer (3 years/34 batches) and I have done all of these things. Every batch was Fermentis yeast; and I've used most of their varieties - ales and lagers

sprinkle dry
re-hydrate with water
re-hydrate in wort
pitch the entire yeast cake from the last batch
wash yeast and store in the 'fridge to 2-3 months
one pack - two packs
no aeration
shake the carboy
aeration stone with two different air pumps and air volumes
paint stirrer on a drill

all made beer - mostly pretty good beer - and all seemed to have acceptable lag times

my next brew I will use one or more of these techniques depending on my mood, and the beer involved.

i like the freedom to keep a variety of yeast on hand so I can brew what I want and when I want to without a lot of advance planning

Cheers

 

[Smellyglove]

What is your fermentation vessel? I had the same exact problem with us-05 repitches. Come to find out it was the fermenter

It's just a plain bucket. But if it produces different results, in either fermenter-type, then I'd say that one can't say that "it doesn't matter", as the results were different.

 

[MikeOhio]

I pretty much use 05 and Notty exclusively for my pale and amber ales respectively. I use wyeast for my cal common, belgian dubbels, and scottish ales when i occasionally do those recipes. Rehydrated 05 one time and the results were exactly the same as previous batches when i didnt. I dont aerate or rehydrate anymore, I so far have always hit my numbers, sanitize really well, and so far have not gotten anything unexpected with my beer. Recently started re-useing those dry yeasts slurries, why waste good yeast!

 

[3 Dawg Night]

In practice, the consecutive steps for direct pitching are:

• Fill the fermenter with 1/3 of the wort volume (up to the top of the CKT cone) at a temperature of 21-29 °C
• Sprinkle the active dry yeast cells directly in the fermenter
• Add the remaining 2/3 of the volume of wort at fermentation temperature to allow for mixing of yeast and wort.

Anyone actually doing this?

Cheers!

No, but I think I'm going to try it this weekend when I brew. I've rehydrated with sterile water up until now.

 

[Gregory T]

I listened to a podcast last night wherein a scientist working for Fermentis stated that their studies have found little to no difference between batches made with rehydrated yeast and identical batches made via pouring packs directly into the fermenter.

The article I linked below offers a brief summary of their findings:

Fermentis - Experts of fermentation, E2U™ direct pitching

And here is a video discussing this, as well as advice to stop aerating (because it is detrimental) when using dry yeast:

I typically use liquid however did dry yeast for a friend’s IPA and a Belgian Blonde. No hydration worked fine.

As far as oxygenating wort I have a Venturi which uses air going from boil to fermentor so all my beers get that.