Do you aerate?

[foxy]

The thing with dried yeast is it goes straight into anaerobic fermentation, has no need whatsoever for any oxygen in the wort, doesn't matter about the excess oxygen, it will get scrubbed during fermentation. I

 

[Stu's Brews]

I think for Homebrew setups it doesn't matter as you're getting more than enough due to the natural splashing into your fermenter...the ratio of the surface area exposed to air as its transferred compared to the total volume of wort will be quite high. In larger brewhouses where hard pipes are used and wort pumped into a very large fermenter f probably doesn't see any air or much agitation in the fermenter, and any agitation wont stir up the whole volume of the wort so only a small proportion of the wort will actually see any air, hence the need to oxygenate in-line during transfer.

I usually splash it around a bit, but don't pay too much attention to it these days and not suffered any negative impacts during fermentation. Certainly don't think using a drill and paddle is necessary, though wont do any harm, and I think what you need is a turbulent action rather than a smooth laminar flow vortex which you'd get with a drill and rattle....I suspect you'd be better off using the paddle manually in a back and forth motion to splash the wort around.

This is true for dried yeasts but as mentioned previously not so much for liquid.

I don't have it to hand at the moment but the 'Yeast' book has a good primer on the details of why it is important.

Fundamentally, you will get a cleaner fermentation and avoid any under-attenuation when you use liquid yeast with a good level of aeration. From my personal experiences, I've generally found this to be true.

 

[Martin Kernick]

Yes, I aerate. As some have said it's beneficial to yeast health and just getting a fermentation happening is not the whole story. The yeast manufacturers recommend it. When you boil a liquid you drive off dissolved gasses. This is why, when you put a pan of water on the hob, it starts bubbling well before it's reached boiling point. So your wort, straight from the boiler will contain very low levels of dissolved O2 - especially if you've followed best practice and chilled it as quickly as possible, becasue there has been no time for oxygen from the air to re-dissolve in the wort. Frothing it up vastly increases the surface area exposed to air and therefore speeds up the rate at which O2 dissolves in the wort. Some people even use bottled O2 and an aeration stone to achieve the desired result - but all that's necessary is that the wort gets the recommended level of O2 and frothing it works very well indeed. Like others I use a sanitised stainless paddle attached to an electric drill (my paddle was from brewfather - doubling as a whirlpool paddle). 2-3 mins is enough to develop a good head of bubbles on a 23L batch and so should produce the recommended (8ppm) O2 levels in the wort.

 

[The-Engineer-That-Brews]

No need to do anything with the wort using dried yeast. I try not to splash at all.
Fill fermenter from the bottom when wort reaches pitching temperature sprinkle dry yeast in a circular motion to prevent clumping. Liquid yeast put fermenter on a sack truck and violently push to and fro for a minute or two.
Big beers just aerate the starter on a stir plate for 3-4 days prior to brew day.

Good tip about using the sack truck

 

[MashBag]

A balloon whisk, would be easier

 

[hoppyscotty]

This is true for dried yeasts but as mentioned previously not so much for liquid.

I don't have it to hand at the moment but the 'Yeast' book has a good primer on the details of why it is important.

Fundamentally, you will get a cleaner fermentation and avoid any under-attenuation when you use liquid yeast with a good level of aeration. From my personal experiences, I've generally found this to be true.

Well it's a new bit of data for me that dried yeasts don't ferment aerobically, so that's interesting. I've always kind of aerated anyway irrespective of the yeasts I use, but these days pretty much exclusively use dried yeasts so good to know the aeration process is not necessary or crucial. Another benefit to modern dried yeasts then! Though I guess is probably means you want to prevent oxygenating during your transfer now.

 

[Agentgonzo]

Well it's a new bit of data for me that dried yeasts don't ferment aerobically, so that's interesting. I've always kind of aerated anyway irrespective of the yeasts I use, but these days pretty much exclusively use dried yeasts so good to know the aeration process is not necessary or crucial. Another benefit to modern dried yeasts then! Though I guess is probably means you want to prevent oxygenating during your transfer now.

As soon as you rehydrate dried yeast, it becomes liquid yeast anyway, so it's not like they are different organisms. When the dried yeast is prepared, it's done in such a manner that it doesn't require dissolved oxygen in the wort to grow/multiply in a healthy fashion - but if oxygen is present it'll still metabolise it, just like any other yeast. So there's absolutely no need to prevent oxygenation during transfer, the yeast will happily metabolise it all during the early stages of fermentation.

 

[Stu's Brews]

Well it's a new bit of data for me that dried yeasts don't ferment aerobically, so that's interesting. I've always kind of aerated anyway irrespective of the yeasts I use, but these days pretty much exclusively use dried yeasts so good to know the aeration process is not necessary or crucial. Another benefit to modern dried yeasts then! Though I guess is probably means you want to prevent oxygenating during your transfer now.

@Agentgonzo beat me to the punch - you don't need to panic about oxygenation when using dried yeasts.

The crucial thing is that if you are using liquid yeast you need to oxygenate sufficiently.

 

[MashBag]

Is there a source for "don't need to oxygenate" theory?

 

[Martin Kernick]

Is there a source for "don't need to oxygenate" theory?

Lallemand say "Aeration is not required for the first pitch"

https://www.lallemandbrewing.com/en...y-yeast-for-quality-consistent-fermentations/

 

[Agentgonzo]

Is there a source for "don't need to oxygenate" theory?

For dried yeasts, both Lallemand and Fermentis say it's not necessary.

Lallemand:

Should I oxygenate my wort?
Our yeast contains adequate reserves of carbohydrates and unsaturated fatty acids to achieve active growth.
It is unnecessary to aerate wort upon first use.

Fermentis:

We don’t recommend aerating the wort in normal conditions. The dry yeast has been produced and dried with a specific know-how of the Lesaffre Group, in order to maximize the Ergosterols content of the cells. This allows the yeast to grow/multiply and ferment well.

(Plus various other sources/FAQ/blogs from the manufacturers recently)

 

[foxy]

Well it's a new bit of data for me that dried yeasts don't ferment aerobically, so that's interesting. I've always kind of aerated anyway irrespective of the yeasts I use, but these days pretty much exclusively use dried yeasts so good to know the aeration process is not necessary or crucial. Another benefit to modern dried yeasts then! Though I guess is probably means you want to prevent oxygenating during your transfer now.

Doesn't matter if oxygen is in the wort, folk will do what they are comfortable with, though the dry yeast will not take up oxygen, whether hydrated or not, the co2 produced scrubs out any oxygen. The last thing you need is for yeast to do is to go back to aerobic respiration, it is rare but does happen. Now that will really ruin a beer.
A good misconception is yeast will take up oxygen when bottling beer, it wont, it will consume the priming sugar but will not use any oxygen which may be in the bottle.

 

[RoomWithABrew]

Why aerate when building a starter?
If you underpitch dried yeast in a no/ low oxygen environment can it happily multiply and then get on and produce alcohol?
I thought the lag phase was the aerobic phase of yeast metabolism building a suitable / maximal cell count to then make alcohol anaerobically.

 

[foxy]

Why aerate when building a starter?
If you underpitch dried yeast in a no/ low oxygen environment can it happily multiply and then get on and produce alcohol?
I thought the lag phase was the aerobic phase of yeast metabolism building a suitable / maximal cell count to then make alcohol anaerobically.

Well I would say most wouldn't make a starter using dry yeast I think it is 5 billion cells per gram so dependent on how many grams are needed just add an extra packet or two. Lag phase I believe is temperature dependent, I tend to pitch at the lower end of the scale so my lag phase would be longer than someone pitching at the high end. The higher the temperature the quicker the ferment and a possibility of unwanted esters.
A Q&A video here a bit drawn out but may be worth a watch for some.

 

[Agentgonzo]

Why aerate when building a starter?

To get healthy yeast. Oxygen is needed to make healthy yeast with good reserves. Health and reserves diminish as yeast multiplies.

If you underpitch dried yeast in a no/ low oxygen environment can it happily multiply and then get on and produce alcohol?

Yes, but you won't get as much yeast after multiplication as you would with a 'correct' pitch rate so not as. It will ferment, but at a slower rate (and with more off flavours I suspect).

I thought the lag phase was the aerobic phase of yeast metabolism building a suitable / maximal cell count to then make alcohol anaerobically.

Lots of things happen. Yes, it's aerobic in the lag phase and it starts to multiply, but yeast multiplies more in the fermentation (or 'log') phase, which is generally anaerobic. But if there is any oxygen still present (or even reintroduced at this stage) then the yeast will use it up as well, the same as what would happen if you cropped yeast from fermentation and chucked it into fresh wort. It's a complex process, and not a simple on/off scenario where it stops consuming oxygen suddenly and changes mode.

 

[MashBag]

Having fiddled about with bigger ferments (500l) in wine, with dried yeast. I would say the lag phase is first, then Aerobic them anaerobic. Underpitching consistantly created a carpet glue smell (for 24 hours or so) before the yeast got started, even at higher temps, with nutrition.

Like has been said, there is a lot going on and it's not 2+2=4

 

[MrJay83]

Only using dried yeast I've splash around (pumping from my BZ), shaken the fermenter and used a slotted spoon with a drill. I've noticed no difference that will make me go over and above just splashing it in now. Probably makes a difference on the larger end of the brewing scale.

 

[hoppyscotty]

Only using dried yeast I've splash around (pumping from my BZ), shaken the fermenter and used a slotted spoon with a drill. I've noticed no difference that will make me go over and above just splashing it in now. Probably makes a difference on the larger end of the brewing scale.

Think this is right. The larger more commercial breweries probably harvest yeast from batch to batch anyway to reduce costs so I'd imagine it becomes even more critical, but on the homebrew scale a few quid on a packet of yeast per batch is neither here nor there.

 

[Agentgonzo]

Think this is right. The larger more commercial breweries probably harvest yeast from batch to batch anyway to reduce costs so I'd imagine it becomes even more critical, but on the homebrew scale a few quid on a packet of yeast per batch is neither here nor there.

I haven't done a brewery tour in well over a decade, possibly two. But when I did (and the few private tours I've had when I got to know the brewers) they said they maintained their own house yeast, washing it between brews to keep free from infections (phosphoric acid wash with a very tight pH range) rather than buying in yeast from commercial suppliers. A couple of them said they got their initial yeast from other breweries (again, rather than buying it in). These were real ale breweries (mostly small microbreweries, but one larger one which has long-since folded (Hampshire Brewery). I don't know whether things have changed since, but it seemed a foreign concept to buy yeast.

 

[MrJay83]

I haven't done a brewery tour in well over a decade, possibly two. But when I did (and the few private tours I've had when I got to know the brewers) they said they maintained their own house yeast, washing it between brews to keep free from infections (phosphoric acid wash with a very tight pH range) rather than buying in yeast from commercial suppliers. A couple of them said they got their initial yeast from other breweries (again, rather than buying it in). These were real ale breweries (mostly small microbreweries, but one larger one which has long-since folded (Hampshire Brewery). I don't know whether things have changed since, but it seemed a foreign concept to buy yeast.

Watch the new GEB brewery tour. Really interesting.