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

[Silver_Is_Money]

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:

https://fermentis.com/en/news-from-fermentis/technical-reviews/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:

 

[Soulshine2]

this is , has been and will still be an argument. Some people just like to futz over their yeast.

 

[mongoose33]

When I was at a BYO boot camp in March, I spoke to the Fermentis people there and asked them about this very thing. Said the same thing.

I asked specifically about not aerating the wort, and they claimed there were enough sterols built up in the dried yeast to support the creation of new cells (daughter cells).

I've struggled with this claim, trying to reconcile it against other things I (think I) know about yeast. And oxygenation. And oxidation (!).

I can accept that the initial cells are well-stocked with sterols, but yeast (non-dried) use oxygen in the wort to create sterols necessary for the building of cell walls. My uncertainty about all this is that the yeast will produce successive generations of yeast and daughter cells, and I wonder how those successive generations get their sterols if there is no oxygen in the wort.

All this balanced against the obvious evidence that using dried yeast works, even when just sprinkled onto the top of the wort.

So, color me confused by all of this.

********

If one accepts the above as true, i.e., that using dried yeast in non-oxygenated wort works just as well as liquid yeast from a starter in oxygenated wort, then the only reason remaining to use liquid yeast in a starter is the speed at which fermentation takes off.

My goal has been fast take-off so the yeast can outcompete any microbiological nasties that have made their way into my wort. My son, a microbiologist and home brewer, says virtually all homebrews are infected by dust falling into them, dust that carries bacteria. The key is for the yeast to outcompete that bacteria before it gets a foothold. Following that logic, I've striven for fast takeoffs of fermentations, and I usually get them, often with evidence of activity within 3-6 hours of pitching.

 

[Dland]

I use dry pitched Fermentis yeasts(mainly US-05, S-189 and W-34/70), and have had batches I dry pitched without additional aeration, other than what it gets in transfer to fermentor, which involves being pumped into cellar. And they have worked out fine at a pitch rate of one pack for 10 gallon batches for ales, two packs for lagers.

Usually I do oxygenate cooled wort with tank O2 though wand(around 5 minutes at .5L per min), since I have the equipment to do so, just before I pitch the yeast.

Once I even used just one pack lager(34/70) yeast for 10 gallons oxygenated, and it made great beer.

The O2 seems to make for a faster start, but did not conduct a formal study. Perhaps it also helps with the last point or two of attenuation, eg 1.008 vs 1.010, but again this is a causal observation, not a controlled study.

 

[Silver_Is_Money]

If one accepts the above as true, i.e., that using dried yeast in non-oxygenated wort works just as well as liquid yeast from a starter in oxygenated wort, then the only reason remaining to use liquid yeast in a starter is the speed at which fermentation takes off.

There are for me still a couple other reasons to choose liquid yeast over dry. The first is that I've convinced myself that I can detect a level of off flavor(s) within all first generation dry yeast fermentations that I do not (necessarily) detect for first generation liquid yeast. This dry yeast off-flavor fortunately ages out (and who knows, perhaps it is off because I have been rehydrating and aerating it). The second is that very few yeast strains are compatible with all of the various processes involved in drying, and that seriously limits the style/flavor choices available.

 

[day_trippr]

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!

 

[Smellyglove]

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.

 

[Bobcatbrewing42]

I use dry pitched Fermentis yeasts(mainly US-05, S-189 and W-34/70), and have had batches I dry pitched without additional aeration, other than what it gets in transfer to fermentor, which involves being pumped into cellar. And they have worked out fine at a pitch rate of one pack for 10 gallon batches for ales, two packs for lagers.

Usually I do oxygenate cooled wort with tank O2 though wand(around 5 minutes at .5L per min), since I have the equipment to do so, just before I pitch the yeast.

Once I even used just one pack lager(34/70) yeast for 10 gallons oxygenated, and it made great beer.

The O2 seems to make for a faster start, but did not conduct a formal study. Perhaps it also helps with the last point or two of attenuation, eg 1.008 vs 1.010, but again this is a causal observation, not a controlled study.

I do the same as you do- one pack of dry ale yeast/5.5 gal or two packs (hydrated) into 5.5 gal of lager. Then oxygenate for a couple of minutes with a tank and stone. Great ferment everythime. I'm amazed that you got a lager to work with one pack of dry yeast. That is way underpitched according to the charts out there.

 

[Smellyglove]

I do the same as you do- one pack of dry ale yeast/5.5 gal or two packs (hydrated) into 5.5 gal of lager. Then oxygenate for a couple of minutes with a tank and stone. Great ferment everythime. I'm amazed that you got a lager to work with one pack of dry yeast. That is way underpitched according to the charts out there.

It depends on fermentation temperature regime. If it's warm or "warm", less is needed, and what you want from your beer. I prefer my lagers cold fermented and use two packs when using dry for 14L of wort.

 

[tellyho]

Totally agree - have just pitched dry into many batches. NEVER an issue. Pushing me further into the "less fuss" camp of brewing. Simplify!

 

[nickatnite26]

Well.....this is certainly eye opening information. I used to just pitch my dry yeast in the wort, but as I started doing more research and gaining more experience, switched to rehydrating the yeast. Skipping this step leaves one less thing to keep track of on brew day.

I am still on the fence regarding aerating the wort, especially after watching the video link above. A short lag time due to aeration of the wort gets any residual oxygen out of the head space on the carbon, but results less healthy yeast. Hmmmm...this gives me a lot to think about. I would be interesting to see a side by side comparison.

 

[50calshooter]

I follow the directions on the yeast. SAFAL says open it and pitch it. They know more about yeast then I ever will.

 

[tellyho]

I have never aerated in my life. 13 years of brewing. Pitch and go.

 

[Dland]

I'm amazed that you got a lager to work with one pack of dry yeast. That is way underpitched according to the charts out there.

It got out to a little slower start, but finished results were no different than if had used 2 packs.

It depends on fermentation temperature regime. If it's warm or "warm", less is needed, and what you want from your beer. I prefer my lagers cold fermented and use two packs when using dry for 14L of wort.

I run my lagers at 54-56F, 40L of wort, and two packs does it for me.

 

[smata67]

The only dry yeast I use is S04 and have used it a number of times the 15 or so years I have homebrewed. I rehydrate as per instructions on the Fermentis datasheet and pitch into the fermenter after having thoroughly aerated the wort with either pure oxygen for about a minute or an aquarium pump for 15 minutes. I see no need to change my procedure, as I have always gotten excellent results with a high degree of reliability, may very well be my favorite all around yeast. No way am I pitching yeast into an un-aerated wort, just does not feel right.

"Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 25 to 29°C (77°F to 84°F). Leave to rest 15 to 30 minutes. Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel."

 

[dpeters]

The only dry yeast I use is S04 and have used it a number of times the 15 or so years I have homebrewed. I rehydrate as per instructions on the Fermentis datasheet and pitch into the fermenter after having thoroughly aerated the wort with either pure oxygen for about a minute or an aquarium pump for 15 minutes. I see no need to change my procedure, as I have always gotten excellent results with a high degree of reliability, may very well be my favorite all around yeast. No way am I pitching yeast into an un-aerated wort, just does not feel right.

"Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 25 to 29°C (77°F to 84°F). Leave to rest 15 to 30 minutes. Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel."

All the more reason to try it! Because you have such a good baseline you will be able to really see the difference. Living on the edge!

 

[Horseflesh]

Last time I did 5 gal of lager, the calculators said I needed FOUR packs of 34/70. The yeast cost more than the grain for that batch so I stopped making lagers!

 

[Soulshine2]

The misconception seems to be the difference between aeration and oxygenation of wort. The only aeration of my wort is simple. I trickle it via hose from the kettle to the fermenter. Not a full open ball valve , just crack it a little (1/4 open?), it will form more aeration that way and as it splashes into the carboy it creates more. By then its already been cooled to near pitching temps ,my OG has been measured and the trickling results in a frothy wort, almost as if it has a bit of head on it and on a couple of occasions nearly an inch. sprinkle an 11g dry pack on top ( rarely do I use 2), apply the bung and a 3 piece airlock and place it on the counter , covering with a carpet pad and topping it off with a brown bath towel.

 

[Soulshine2]

Last time I did 5 gal of lager, the calculators said I needed FOUR packs of 34/70. The yeast cost more than the grain for that batch so I stopped making lagers!

thats a lot. I was very impressed by 34/70 when I used it. tons of kraeusen .

 

[Dland]

Last time I did 5 gal of lager, the calculators said I needed FOUR packs of 34/70. The yeast cost more than the grain for that batch so I stopped making lagers!

Instructions on packet say 11.5G for every 20-30L wort. 1 pack is 11.5G. I use O2 and pitch into 40L with good result. Note S04, and other Fermentis ale yeast pitch at half that rate.

The only dry yeast I use is S04 and have used it a number of times the 15 or so years I have homebrewed. I rehydrate as per instructions on the Fermentis datasheet."

Instructions on pack says "Sprinkle into wort."

Sorry, best picture I could manage, but so you know I'm not making it up.

Also, not really trying to change anyone's mind who's beliefs are set and like how they are brewing, but lots of other homebrewers come here for guidance.

In my opinion, some of the stuff I see on this forum about yeast could be discouraging. All I'm saying is it does not have to be that complex or expensive.

 

[Silver_Is_Money]

The misconception appears to be that it is hard to fully grasp and accept that yeast only require oxygen in order to produce sterols necessary for their reproduction and for alcohol production. If sufficient of the sterols are already present within the yeast packet there is no need for the yeast to preliminarily produce them (which they can only do in the presence of oxygen) and they can get straight on to making alcohol.

 

[Soulshine2]

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.

 

[Soulshine2]

The misconception appears to be that it is hard to fully grasp and accept that yeast only require oxygen in order to produce sterols necessary for their reproduction and for alcohol production. If sufficient of the sterols are already present within the yeast packet there is no need for the yeast to preliminarily produce them (which they can only do in the presence of oxygen) and they can get straight on to making alcohol.

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

 

[Beerwildered]

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:

https://fermentis.com/en/news-from-fermentis/technical-reviews/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:

Maybe I’m a cynic, but I have a hard time trusting “scientific study” claims when they are made by a manufacturer about their own product. They obviously benefit from the outcome.

 

[smata67]

View attachment 626466

Instructions on packet say 11.5G for every 20-30L wort. 1 pack is 11.5G. I use O2 and pitch into 40L with good result. Note S04, and other Fermentis ale yeast pitch at half that rate.



Instructions on pack says "Sprinkle into wort."

Sorry, best picture I could manage, but so you know I'm not making it up.

Also, not really trying to change anyone's mind who's beliefs are set and like how they are brewing, but lots of other homebrewers come here for guidance.

In my opinion, some of the stuff I see on this forum about yeast could be discouraging. All I'm saying is it does not have to be that complex or expensive.

They can only put so much information on a packet. I'm going by the datasheet dated March 2018 which I have attached, so you know I'm not making it up , whereas the rehydration method is mentioned. I do note that on neither the packet or the datasheet is there a requirement to aerate. I did find some older datasheet that mentions aeration, but only as a method of stirring up the wort after direct pitch, not necessarily to supply oxygen.

So it appears Fermentis is pretty consistent in not requiring aeration. And this is going back aways, because there are plenty of posts regarding these issues about necessity of rehydration or oxygen going back over a decade. To say that rehydration is also not necessary is kind of self-serving, it eliminates that step. And if on top of that, you don't need to aerate, that gives dry yeast a clear advantage over liquid for the strains where dry yeast is available. I may just direct pitch without aeration for the heck of it eventually, after all, beer making is very forgiving, God knows I've done things over the years that I was sure would ruin the batch and it came out okay.

 

[Silver_Is_Money]

Fermentis has promised that soon all of their instructions will be unified and updated to indicate no need for rehydration and no need for aeration. Current advice is outdated. If the new advice makes for better beer, both Fermentis and the home brewer win.

 

[TooManyTacos]

I have always rehydrated simply because its easier for me. I've pitched directly into wort before, and the dried yeast will stick to some of the left over bubbles of StarSan, which I'm sure is not good for the yeast. So I started rehydrating because it's not difficult in the least, can only benefit they yeast, and the slurry will mostly sink to the bottom and will not get caught in the stars bubbles.

 

[shoengine]

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

Well, one is a liquid, the other is a solid. Hard to have dissolved oxygen in a solid.

 

[Silver_Is_Money]

I have always rehydrated simply because its easier for me. I've pitched directly into wort before, and the dried yeast will stick to some of the left over bubbles of StarSan, which I'm sure is not good for the yeast. So I started rehydrating because it's not difficult in the least, can only benefit they yeast, and the slurry will mostly sink to the bottom and will not get caught in the stars bubbles.

Fermentis advises to add yeast (straight from the packs) to the first 1/3 of the wort in the fermenter, and then add the remaining 2/3 of the wort on top of it in the fermenter to provide simultaneous mixing and hydration. This is their idea of a proper no aeration dry yeast addition.

 

[BrewnWKopperKat]

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. Ideally, the yeast will be added during the first part of the filling of the vessel; in which case hydration can be done at wort temperature higher than fermentation temperature, the fermenter being then filled with wort at lower temperature to bring the entire wort temperature at fermentation temperature

 

[JONNYROTTEN]

I've tried paint stirrer on a drill and dumping from bucket to bucket to get as much oxygen in as possible. Ive also not aerated at all.

Zero difference.

I've never rehydrated

I've never had dry yeast fail me...not once

Waste of time and effort

 

[mabrungard]

My experience is that rehydration may not be necessary in all cases, but rehydration is very helpful when the wort is at lager temperatures. I recently brewed a leichtbier and pitched 34/70 dry into the fermenter. Since this was a 1.040 beer, I estimated that the supplied yeast population would be sufficient. That beer did end up fermenting well and no off or estery by-products were notable. The thing that alarmed me was the 3 day delay in signs of fermentation by either airlock bubbles or Tilt reading. I'm hypothesizing that the increased viscosity of the colder wort inhibits the rehydration of yeast cells.

In my opinion, yeast rehydration is a worthwhile thing to do to enhance the performance and speed of your fermentation. I strongly disagree with any recommendation for the user to employ 'warm' water for rehydration since its more possible that the water may be too hot for the yeast. Water should be at or below body temperature to avoid killing the yeast (say 20C to 35C). Using 1 to 2 grams of Epsom salt per Quart of RO water is an ideal rehydration media.

As evidenced by my experience, rehydration still isn't a requirement, but it is a good idea.

PS: I don't aerate when pitching dry yeast into low to moderate gravity wort. I believe that the dry yeast does have enough sterols to supply future budding.

 

[Horseflesh]

> Instructions on packet say 11.5G for every 20-30L wort.

And if you look at a yeast calculator, and conservatively factor in the age of the pack, gravity, desired cell count for a lager, etc etc it can add up to three packs and change. Or, a multi-step starter with liquid yeast.

If I can ferment a 1.050 lager successfully with 1-2 dry packs I would be very happy.

 

[mediant]

Here's a big Fermentis presentation on the matter, that states essentially the following regarding their dry yeast pitching conditions:

• Temperature does not significantly impact without or with moderate agitation.
• Type of media does not significantly influence the viability

This essentially means they suggest to pitch at lager temperatures or rehydrate in distilled water without hesitation.

 

[Soulshine2]

Maybe I’m a cynic, but I have a hard time trusting “scientific study” claims when they are made by a manufacturer about their own product. They obviously benefit from the outcome.

why wouldnt you trust the manufacturer when they tell you something isnt necessary. How exactly would they benefit further by telling us their yeast needs no extreme aeration nor a starter made? Theyre still going to sell yeast, grown , harvested and cultivated by "scientists" when what they should refer to them as Zymurgists. Thats their business. They put out pitch rate charts and use suggestions .
Generally, if you follow any manufacturers instructions ,do's and don'ts,no matter the product, it usually results in a better final result for the consumer. Its when the instructions are not followed is when the problems arise and results may vary or stray from the expectations. It is then that warranties and replacements are usually "voided" .

 

[Soulshine2]

My experience is that rehydration may not be necessary in all cases, but rehydration is very helpful when the wort is at lager temperatures. I recently brewed a leichtbier and pitched 34/70 dry into the fermenter. Since this was a 1.040 beer, I estimated that the supplied yeast population would be sufficient. That beer did end up fermenting well and no off or estery by-products were notable. The thing that alarmed me was the 3 day delay in signs of fermentation by either airlock bubbles or Tilt reading. I'm hypothesizing that the increased viscosity of the colder wort inhibits the rehydration of yeast cells.

In my opinion, yeast rehydration is a worthwhile thing to do to enhance the performance and speed of your fermentation. I strongly disagree with any recommendation for the user to employ 'warm' water for rehydration since its more possible that the water may be too hot for the yeast. Water should be at or below body temperature to avoid killing the yeast (say 20C to 35C). Using 1 to 2 grams of Epsom salt per Quart of RO water is an ideal rehydration media.

As evidenced by my experience, rehydration still isn't a requirement, but it is a good idea.

PS: I don't aerate when pitching dry yeast into low to moderate gravity wort. I believe that the dry yeast does have enough sterols to supply future budding.

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?

 

[Soulshine2]

Fermentis advises to add yeast (straight from the packs) to the first 1/3 of the wort in the fermenter, and then add the remaining 2/3 of the wort on top of it in the fermenter to provide simultaneous mixing and hydration. This is their idea of a proper no aeration dry yeast addition.

I've never seen that .I'm not doubting you but where is it written?

 

[Northern_Brewer]

I can accept that the initial cells are well-stocked with sterols, but yeast (non-dried) use oxygen in the wort to create sterols necessary for the building of cell walls. My uncertainty about all this is that the yeast will produce successive generations of yeast and daughter cells, and I wonder how those successive generations get their sterols if there is no oxygen in the wort.

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

 

[Silver_Is_Money]

I've never seen that .I'm not doubting you but where is it written?

It was actually linked in my first post starting this thread, but I've also copied the web link here:

https://fermentis.com/en/news-from-fermentis/technical-reviews/e2u-direct-pitching/

 

[mongoose33]

Dried yeast are stuffed with sterols, about 16% IIRC compared to 2% in normal yeast. So the first generation will have 8%, 2nd generation 4%, 3rd generation 2%. 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.

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.