Aeration Question

[pc_trott]

I've yet to start my first brew. Call me a nervous Nellie, but I want to be sure I have all my ducks in a row before I start. I've still got to pick up a few things to complete my starting gear, but I'm thinking I'll bite the bullet and start boiling water tomorrow morning. But I have this question on aerating the wort before adding yeast.

I'm using a six-gallon carboy for the primary. The directions in my kit (Block Party Amber Ale from Northern Brewers) say to put two gallons of water in the primary, then add the wort, then top up to five gallons with more water. Will pouring those liquids into the primary via a funnel aerate the wart enough for the yeast?

The directions also say to rock the primary back and forth for several minutes for aeration before adding the yeast, but is that necessary when the primary is a carboy and you are pouring the stuff in, letting it drop a couple of feet in a cascade?

Thanks for any advice!

 

[mongoose33]

Since it's your first brew, err on the side of more rather than less.

Just pouring in the water isn't, IMO, going to do what you need.

HOWEVER, is it dry yeast you're using? Most of the dry yeast I'm familiar with does not require aeration. Yeast need oxygen as a precursor to build cell walls, but dry yeast such as S-05 has been created where the yeast already has a ready supply of those building blocks.

So, if dry yeast, then just pouring in the water should be just fine.

 

[foolsbrew]

You can skip both the shaking and pouring it from above. If I remember correctly, you have to shake for like 30 minutes to make a difference. Pouring from above is easier to do and does make some difference though, so I would do that just for some peace of mind.

Get a cup of water, room temperature or the same temperature as your wort, sprinkle the yeast in and let it for 15 to 30 minutes. Pour this to your wort. This is called rehydrating the yeast. Sprinkling directly into wort usually kills almost half the yeast cells, so this will be more effective than anything else you do.

Even if you do none of these though, dry packs contain more than enough cells to be sufficient, so you have no reasons to worry.

Good luck.

 

[RPh_Guy]

Sprinkling directly into wort usually kills almost half the yeast cells

This is not true for Fermentis yeast, which is specially produced to allow for rehydration in wort.

I haven't seen data for rehydration other brands of dry beer yeast.

Wine yeasts should generally be rehydrated in water, but not at room temp. Elevated temp is required, around 95-100°F.

 

[foolsbrew]

This is not true for Fermentis yeast, which is specially produced to allow for rehydration in wort.

I haven't seen data for rehydration other brands of dry beer yeast.

Wine yeasts should generally be rehydrated in water, but not at room temp. Elevated temp is required, around 95-100°F.

I'd like to see the data. I highly doubt the cells of Fermentis yeast is somehow magically able to differentiate what the cell absorbs while the yeast from other brands cannot. (edit: This did not age well. Turns out there is indeed a difference )

Fermentis claims to have 100B cells per pack, while the real number is >200B. They essentially assume you will kill a decent chunk of them and still end up with a viable amount. This isn't a bad thing, they are my choice of yeast as well. Nevertheless, rehydrating in warm water will indeed leave you with more viable cells. You are fine with pitching direct, but pitching rehydrated is better.

Dry yeast will work when pitched directly to the cold wort, there are no doubts about that, but the ideal rehydration environment is accepted to be warm water. If you are able to point me to some sources or papers though, I am ready to change my opinion.

Yeast: A Practical Guide To Beer Fermentation(Chris White, Jamil Zainasheff)

If you are working with dry yeast, determining how much to pitch is relatively easy. Most dry yeast contains about 7 billion to 20 billion cells per gram, depending on the cell size and other nonyeast material, but that is not the number of viable cells per gram you will have once you rehydrate the yeast. That depends on a number of factors, such as storage and rehydration techniques. Find out from your supplier how many viable cells per gram you can expect (which might be as low as 5 billion), then simply divide the number of cells needed by the number of viable cells, and you will know the weight in grams of dry yeast needed. Of course, this assumes all the yeast is active and that you properly rehydrate it following the manufacturer’s recommendations before pitching. Failure to rehydrate dry yeast properly will result in the death of approximately half the cells.

Dr. Clayton Cone(Lallemand)

The dried yeast cell wall is fragile and it is the first few minutes (possibly seconds) of rehydration that the warm temperature is critical while it is reconstituting its cell wall structure. As you drop the initial temperature of the water from 95 to 85 or 75 or 65F the yeast leached out more and more of its insides damaging the each cell. The yeast viability also drops proportionally. At 95 - 105 F, there is 100% recovery of the viable dry yeast. At 60F, there can be as much as 60% dead cells.

For the initial few minutes (perhaps seconds) of rehydration, the yeast
cell wall cannot differentiate what passes through the wall. Toxic
materials like sprays, hops, SO2 and sugars in high levels, that the yeast
normally can selectively keep from passing through its cell wall rush right
in and seriously damage the cells. The moment that the cell wall is
properly reconstituted, the yeast can then regulate what goes in and out of
the cell. That is why we hesitate to recommend rehydration in wort or
must. Very dilute wort seems to be OK.

 

[Robert65]

I've never seen any evidence supporting the "50% kill rate" for any yeast. I have, however, seen studies showing 2-4% loss of viability without rehydration. I'm not saying it's not true in some cases. I'm just saying that I've heard this parroted for decades without anybody citing a source. I'd like to know where it came from. Regarding Fermentis having a unique manufacturing process, I haven't seen any evidence that theirs differs significantly from others', either. Again, not saying it isn't true, just not clearly supported. Anecdotal reports indicate that brewers see similar results using the same direct pitching procedure with all manufacturers' yeasts.

 

[foolsbrew]

I have, however, seen studies showing 2-4% loss of viability without rehydration.

Do you mind finding them? I'd like to read.
Thanks.

 

[Robert65]

Do you mind finding them? I'd like to read.
Thanks.

I'll try if I can. Might have something in cloud storage, it's been some time since I was concerned with this. But I'm pretty sure I was provided some of this in a back and forth email exchange with tech reps from the manufacturers several years ago. I've found that both Lallemand and Fermentis are good at responding to inquiries regarding technical information.

 

[foolsbrew]

I'll try if I can. Might have something in cloud storage, it's been some time since I was concerned with this. But I'm pretty sure I was provided some of this in a back and forth email exchange with tech reps from the manufacturers several years ago. I've found that both Lallemand and Fermentis are good at responding to inquiries regarding technical information.

Infact that's my source My understand is pitching directly is only fine because you end up with more than viable cells either way, but it's not unnecessary to rehydrate.

Anyway, I hope you can find something.

 

[Robert65]

Yes, that's the biggest takeaway here. However many cells survive, they really hit the ground running.

 

[BrewnWKopperKat]

I'd like to read.

While this [link] isn't likely to be considered a "formal" study, it does offer results. More importantly, it offers an description of the methods used so that others could attempt to reproduce.

 

[foolsbrew]

While this [link] isn't likely to be considered a "formal" study, it does offer results. More importantly, it offers an description of the methods used so that others could attempt to reproduce.

Interesting. I hope we get more reproduction on this.

The results themselves contradict far more respectable sources, which also did post results. It's hard to trust it when the previous head/director of Lallemand is pointing at different numbers. That's not to say I'd trust the latter without question though, their yeast calculator clearly suggests more yeast than necessary, but I guess I find that excusable when it's their business. I only trust them in this because it doesn't help them sell more yeast

Thanks for doing this and sharing. It's interesting that you got different results than Sean Terrill, Dmitri Serjanov (BKYeast), and Lallemand. It makes me wonder what was different about your trial. http://seanterrill.com/2011/04/01/dry-yeast-viability/ https://bkyeast.files.wordpress.com/2013/03/meschart.jpg https://web.archive.org/web/20160425030357/http://www.hbd.org/hbd/archive/3301.html

 

[RPh_Guy]

I'd like to see the data.

See attached PDF.
It shows quite clearly that Fermentis yeast does not benefit at all from rehydration in water or at an elevated temperature.

This was corroborated by the recent independent study linked above on Reddit, with US-05. (2017 study)

I've never seen any evidence supporting the "50% kill rate" for any yeast.

There are indeed a couple older studies I've found out there that show this.

Danstar Nottingham
https://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/

US-05
http://seanterrill.com/2011/04/01/dry-yeast-viability/
Note the date. This study is older and Fermentis has clearly improved their technology since then.

 

[foolsbrew]

See attached PDF.
It shows quite clearly that Fermentis yeast does not benefit at all from rehydration in water or at an elevated temperature.

This was corroborated by the recent independent study linked above on Reddit, with US-05. (2017 study)

There are indeed a couple older studies I've found out there that show this.

Danstar Nottingham
https://bkyeast.wordpress.com/2013/03/13/more-on-yeast-rehydration/

US-05
http://seanterrill.com/2011/04/01/dry-yeast-viability/
Note the date. This study is older and Fermentis has clearly improved their technology since then.

I wouldn't have thought the improvements in yeast production just in 5 years would be enough to make such a drastic difference, but color me surprised. This also explains why the reddit user found no difference.

Thanks for the data, I won't rehydrate my Fermentis yeast any longer and will refrain from recommending people to do so. You learn something new every day

 

[BrewnWKopperKat]

The results themselves contradict far more respectable sources, which also did post results. It's hard to trust it when the previous head/director of Lallemand is pointing at different numbers.

US-05 is not a Lallamand stain.

A piece of advice that I got from a pro brewer a number of years ago (just before the E2U announcement): treat each strain of dry yeast differently.

I won't rehydrate my Fermentis yeast any longer and will refrain from recommending people to do so.

Simplest thing possible may be to suggest following the current instructions from the dry yeast lab.

• http://fermentis.com/fermentation-solutions/you-create-beer/
• https://fermentis.com/en/tips-n-tricks/questions-and-answers
• https://www.lallemandbrewing.com/en/united-states/products/brewing-yeast/
• https://mangrovejacks.com/collections/craft-series-yeasts

 

[Robert65]

The caveat to "following manufacturer's instructions" should be that Mangrove Jacks give the same instructions for all yeasts. Yet they have no lab or manufacturing facilities. They simply buy yeasts from Fermentis, Lallemand, and Mauribrew, and repackage and resell them. So if different yeasts really need different treatment per the manufacturers, this is not reflected in the information provided. Or perhaps MJ serendipitously states the truth: that no yeast requires rehydration, but all may benefit from it? Hmm.

 

[mongoose33]

I wouldn't have thought the improvements in yeast production just in 5 years would be enough to make such a drastic difference, but color me surprised. This also explains why the reddit user found no difference.

Thanks for the data, I won't rehydrate my Fermentis yeast any longer and will refrain from recommending people to do so. You learn something new every day

FWIW, you aren't alone in having issues with this. Took me a while to accept it too. Not sure I have completely gotten over the hump, but it seems to work to just direct pitch with no rehydration, and no oxygenation. Who'd a thunk?

 

[BrewnWKopperKat]

The caveat to "following manufacturer's instructions" should be that Mangrove Jacks give the same instructions for all yeasts. Yet they have no lab or manufacturing facilities. They simply buy yeasts from Fermentis, Lallemand, and Mauribrew, and repackage and resell them. So if different yeasts really need different treatment per the manufacturers, this is not reflected in the information provided. Or perhaps MJ serendipitously states the truth: that no yeast requires rehydration, but all may benefit from it? Hmm.

Sorry, I just wanted to include MJ in the list for completeness.

I'll strike it out of the list I posted (although the link is still clickable). Next time I'll consider including a category for yeast repackagers

 

[hottpeper13]

Wow this one took a weird turn. Now to answer your question, I believe since you're putting 2 gal of tap water(not boiled) into the fermenter, using dried yeast , and generally splashing that into the carboy, you need not worry about adding more O2.

 

[jack13]

At least one wine kit I've used specifically said not only to sprinkle the yeast across the surface (as opposed to rehydrate), but to just leave it on the surface and not mix it in. Anyone know the reason for that? I get why mixing isn't necessary, but the specific instruction to not do it struck me. Maybe just to avoid one more potentially contaminating contact?

 

[Robert65]

At least one wine kit I've used specifically said not only to sprinkle the yeast across the surface (as opposed to rehydrate), but to just leave it on the surface and not mix it in. Anyone know the reason for that? I get why mixing isn't necessary, but the specific instruction to not do it struck me. Maybe just to avoid one more potentially contaminating contact?

I would say it does help to avoid one more potentially contaminating step, but also lets the yeast hydrate at its own pace, not forcing it to go too quickly, which is at the heart of the rehydrate/ don't rehydrate question.

 

[pc_trott]

Wow this one took a weird turn. Now to answer your question, I believe since you're putting 2 gal of tap water(not boiled) into the fermenter, using dried yeast , and generally splashing that into the carboy, you need not worry about adding more O2.

Thanks, that raises another question. Is it unnecessary to boil tap water before using? Is tap water considered already sterile, due to the chlorination?

 

[WhiteRhyno]

Thanks, that raises another question. Is it unnecessary to boil tap water before using? Is tap water considered already sterile, due to the chlorination?

I always boil my tap water. Theory is that yes the water is sterile, but there may be cooties living in the fawcett, so better to err on the side of caution.
With a bit of planning it's not too much of a pita, you just have to make sure it is down to the correct temp before pitching, otherwise you will compromise your brew

 

[Robert65]

If it *is* chlorinated, then you want to boil that off anyway, you don't want even a small amount going into your beer to avoid off flavors. No harm at all in boiling and cooling down to the desired temperature no matter what.

 

[RPh_Guy]

At least one wine kit I've used specifically said not only to sprinkle the yeast across the surface (as opposed to rehydrate), but to just leave it on the surface and not mix it in. Anyone know the reason for that? I get why mixing isn't necessary, but the specific instruction to not do it struck me. Maybe just to avoid one more potentially contaminating contact?

Yeast cells are extremely vulnerable to shear stress as they are rehydrating (again, with the exception of Fermentis yeast). Stirring or agitating will further damage the cells, and they're already being damaged by rehydrating in the must at a low temp.
It has absolutely nothing to do with contamination.

If you are making wine you should follow a good rehydration protocol; it will make a big difference.

Thanks, that raises another question. Is it unnecessary to boil tap water before using? Is tap water considered already sterile, due to the chlorination?

Tap water is definitely not sterile.
Boiling would help sanitize it.

You should also remove chlorine or chloramine. Boiling removes chlorine but not chloramine -- for that you should use part of a Campden tablet. Check with your water source to see which they are using.

 

[jack13]

Yeast cells are extremely vulnerable to shear stress as they are rehydrating (again, with the exception of Fermentis yeast). Stirring or agitating will further damage the cells, and they're already being damaged by rehydrating in the must at a low temp.
It has absolutely nothing to do with contamination.

If you are making wine you should follow a good rehydration protocol; it will make a big difference.

Tap water is definitely not sterile.
Boiling would help sanitize it.

You should also remove chlorine or chloramine. Boiling removes chlorine but not chloramine -- for that you should use part of a Campden tablet. Check with your water source to see which they are using.

Man, I've been stirring vigorously after putting the yeast into the water to rehydrate, then again after 20 minutes right before pitching. For years.

 

[ncbrewer]

Yeast cells are extremely vulnerable to shear stress as they are rehydrating (again, with the exception of Fermentis yeast).

Fermentis has changed some of their recommendations. They now recommend only gentle stirring, if any. See
https://fermentis.com/wp-content/uploads/2019/10/Brochure_Tips_and_Tricks_BAT_BD.pdf

 

[RPh_Guy]

Fermentis has changed some of their recommendations. They now recommend only gentle stirring, if any. See
https://fermentis.com/wp-content/uploads/2019/10/Brochure_Tips_and_Tricks_BAT_BD.pdf

The Fermentis presentation I linked above shows that stirring does harm Fermentis yeast (nowhere near the extent that it harms other brands of yeast), so it's not surprising they recommend to minimize stirring.

 

[BrewnWKopperKat]

https://www.homebrewtalk.com/forum/...-rate-and-bulk-dry-yeast.673851/#post-8761016 has some additional information from @ncbrewer & Fermentis.

Personally, I don't think I can stir by hand at 100 RPM

 

[foolsbrew]

https://www.homebrewtalk.com/forum/...-rate-and-bulk-dry-yeast.673851/#post-8761016 has some additional information from @ncbrewer & Fermentis.

Personally, I don't think I can stir by hand at 100 RPM

That's just a little over one stirring in a second right?
It should be very easy if you do it like this:

She is doing it slowly in the video but once you are used to the technique, you can go pretty fast Even when it's slow the fork moves around like 5 times in a second.