Wort Aeration

[alowen474]

At the risk of stating the obvious, all this stuff on flow-rates and whathaveyou is critically dependant on whether one is oxygenating a starter or the whole wort. It was concluded way back at the start of this thread that oxygenating the starter alone is preferable in order to avoid beer staling. It would sure also cut down on O2 consumption which, unlike air, isn't free. I would add another, less-recognised point: that replicating yeast puts out a different spectrum of byproducts than fermenting yeast. I think this is an implicit reason why folks sometimes recommend throwing the starter supernatant away, although those byproducts could actually be desirable in certain beer styles. A final bleeding obvious observation: oiling the wort is not a direct substitute for big yeast starters, due to the greater yeast growth in the former.

Being reasonably new to aeration and oxygenation, wouldn't aerating the starter only help grow a healthy starter?
Isn't the starter the vehicle to provide enough yeast cells so that the reproduction phase of the fermentation cycle is reduced to a healthy level? If this was the case the wort would still need oxygen at 10-15ppm for the yeast to grow to the right quantity would it not?
Maybe I need to read some more!!

 

[muckanic]

And I guess the whole olive oil thing leaves me red faced and a pretty big slow moving target for ya huh? Or was that too bleeding obvious?

What may seem bleeding obvious to you, is not to me. Why not try to be less condecending? I don't know you from a bar of soap and you certainly don't know me which I guess makes all the easier. It's a forum not a lecture hall.

Mate, try switching to lite! You're not anybody's target and I for one am interested in all these olive oil experiments. I was actually throwing up more questions than answers, so I'm hardly in a position to lecture anyone.

Peace :icon_chickcheers:

 

[hazard]

That what's I thought in my limited knowledge and reading but I did ask Frank again separately later on and he was pretty positive about the 3ml to 21lt of wort. Anyway I will keep you posted to the results.

Chappo, do you have results to report? I am very keen to try this technique, would appreciate some feedback on how your brew went,

hazard

 

[chappo1970]

Hazzard it's perfect IMO. No noticable faults what so ever. I kegged it last night, bottled a couple of samples for the monthly BABBS meeting (I will let them judge as I could be biased) and sipping away on what is almost a perfect Little Critters Bright Ale. There is definitely something to this so I am going one further this time.

I did a double batch of Moonshadow's Drowned Faery Golden Ale. Same batch, same boiler and same cube. I will brew 18lts with Oxygen aeration and 18lts with 1ml of olive oil. I will make a 3lt starter and pitch 1.5lt into each batch. Therefore the ONLY variable will be he aeration method. I going to try to note high kraussen time, attenuation and overall fermentations times. Just waiting to get an Irish red ale out of the ferment fridge first so I can get both in there at the same time.

BTW: Head retention is fine

 

[hockadays]

Being reasonably new to aeration and oxygenation, wouldn't aerating the starter only help grow a healthy starter?
Isn't the starter the vehicle to provide enough yeast cells so that the reproduction phase of the fermentation cycle is reduced to a healthy level? If this was the case the wort would still need oxygen at 10-15ppm for the yeast to grow to the right quantity would it not?
Maybe I need to read some more!!

I came to the same conclusion when reading the start of this thread.

 

[Mantis]

Me too. Since going to BIAB and no chill, my brews are taking so much longer to kick off.

Before, I was doing partials (BIAB), and throwing the whole contents of the kettle in the fermenter break and all. Then giving the contents a damn good thrashing with a long spoon before pitching yeast. These would all be showing good signs of fermentation within hours.

Now with the no chilling and biab, I am leaving most of the hot break behind in the kettle, no chill and leave more break behind in the cube. Now it takes from the morning of pitching to the next day before fermentation kicks in properly.

I dont use, and never have used starters so, maybe this is why so many do

If a wee drop of oil will help, I would give it a go :icon_cheers:

 

[Mantis]

Jeez, you have to type quick here
Thanks Chappo,, it sounds promising eh

 

[mika]

I came to the same conclusion when reading the start of this thread.

Yeast needs oxygen to grow, you need oxygen within the wort you're pitching into to allow the yeast to multiply without stress.
If you oxygenate your starter, then your starter has nice healthy yeast, then as soon as you throw them into a full size batch, with no oxygen, they have to draw on their reserves to reproduce and they get stressed and can throw up by-products that will affect the taste. Unless you're starter contains enough yeast that it won't reproduce, but then without any kind of reproduction you'll lose your ester production, probably fine for a lager, but a bit bland in an english ale.
It's a fine balancing act, if you're looking to get it 100% right. You've got to remember that yeast don't want to make alcohol, it's bad for them. They only start producing alcohol when there's no other option.
If you only have the ability to oxygenate the starter, fine go with that, it's better than nothing and a lot of people have been getting away with that (or less than that) for a long time. But if you can oxygenate the starter and the wort you're pitching too, now you're really brewing.

 

[hazard]

Hazzard it's perfect IMO. No noticable faults what so ever. I kegged it last night, bottled a couple of samples for the monthly BABBS meeting (I will let them judge as I could be biased) and sipping away on what is almost a perfect Little Critters Bright Ale. There is definitely something to this so I am going one further this time.

BTW: Head retention is fine

Thanks Chappo, sounds good. I will be brewing something next weekend (Irish Red Ale methinks) so will try this. Can I confirm the process:
1. make starter - approx 1.5 L. I don't have a stir plate, so i use a 2L juice bottle covered with cling wrap and shake every time I walk past it.
Question - is a stir plate even needed? If olive oil replaces oxygen then there's no need for a stir plate? I have been following the "tight arse stir plate" thread with interest because I am a tight arse, but if oil is just as good then I can save a few more bucks.
2. add around 0.5ml olive oil (i have seen suggestions that this should be done by dipping a toothpick or pin into oil then dipping into the starter.
Question - when to add oil? When yeast is added to starter? At high krausen? When fermentation is completed?
3. After wort reaches fermention temp, add starter. No stirring or aeration required.
Question - no oxygen added to wort, is there any more oil needed in the wort?

I am getting really good heads on my beer now and am glad to hear that small amount of oil doesn't affect head retention. Thanks for any further advice on this.

Regards, Hazard

 

[jonocarroll]

Yeast needs oxygen to grow, you need oxygen within the wort you're pitching into to allow the yeast to multiply without stress.
If you oxygenate your starter, then your starter has nice healthy yeast, then as soon as you throw them into a full size batch, with no oxygen, they have to draw on their reserves to reproduce and they get stressed and can throw up by-products that will affect the taste. Unless you're starter contains enough yeast that it won't reproduce, but then without any kind of reproduction you'll lose your ester production, probably fine for a lager, but a bit bland in an english ale.
It's a fine balancing act, if you're looking to get it 100% right. You've got to remember that yeast don't want to make alcohol, it's bad for them. They only start producing alcohol when there's no other option.
If you only have the ability to oxygenate the starter, fine go with that, it's better than nothing and a lot of people have been getting away with that (or less than that) for a long time. But if you can oxygenate the starter and the wort you're pitching too, now you're really brewing.

If yeast became stressed by going from starter to unaerated wort, wouldn't they get stressed once they've used up the oxygen in an aerated wort? You're also assuming that the yeast is pitched at the moment the oxygen runs out - surely it's possible that the yeast have started the fermentation phase in the starter already.

The point of this thread was the question - "do you need to aerate the wort if you've aerated the starter enough?" The critical part for any answer is assuming that the starter has been aerated enough. Several options exist beyond this - pitch the entire starter, esters and all; pitch after high-krausen; etc.

Many people have produced arguments against aerating the wort - oxidisation for one - your argument of 'yes, you've gotta' will need some more support.

 

[Sammus]

Just wondering what the difference is between medical grade 02, and run of the mill 02 from an oxy acetylene kit.

I remember this being discussed at length several times over in many threads a few years back, the general consensus was that the medical grade O2 has a different thread on the cylinders. The gas itself - same O2 from the same tank, as far as hiring from BOC is concerned anyway, which was verified by several BOC employees.

 

[muckanic]

but then without any kind of reproduction you'll lose your ester production, probably fine for a lager, but a bit bland in an english ale.

Bear in mind there are esters and esters. IIRC, the pathways for the solventy acetate esters are different than for the fruitier and higher weight esters, which rely on fusel oil production. I don't have Fix's book at my fingertips to be any more specific than that - will have to look it up.

If you only have the ability to oxygenate the starter, fine go with that, it's better than nothing and a lot of people have been getting away with that (or less than that) for a long time.

Except that pros doing continuous production probably aren't too worried about starters either, as they often have a yeast cake to work with. I wonder how many of them oxygenate the wort as well in that case? In addition, how many amateurs are going to the bother of separating their wort from the cold break?

As a test, I added 3mL/23L olive oil to an all-sugar brew of SG 60 that had stalled on me at about 5% ABV. It didn't revive fermentation, quite possibly because the lipids were being added later than when they were needed. It did however result in a visible globule slick and the aroma of pizza. Once again, those problems could have been caused by the oil not being assimilated properly, but just from that experience I would guesstimate that those quantities are way, way too much. Rice bran oil has a much more neutral nose, at the disadvantage of a lower monounsaturate ratio.

 

[newguy]

From personal experience, no aeration = stuck fermentation + "Belgian" character, though not as pleasant as a Belgian beer. It is tough to describe, but once you taste it, you know the flavour.

A local micro has related a story, many times, of a brewer he used to employ who hated cold break and took any step he could imagine to separate the wort from the cold break. He was eventually let go because every batch he brewed ended up being stuck (underattenuated) and nothing they did would rouse the yeast and coax it to properly attenuate the wort. Once they went back to the normal procedure which didn't separate cold break from the wort, the problems went away.

 

[jonocarroll]

From personal experience, no aeration = stuck fermentation + "Belgian" character, though not as pleasant as a Belgian beer. It is tough to describe, but once you taste it, you know the flavour.

'no aeration' at all or no aeration of the wort, but aeration of the starter?

A local micro has related a story, many times, of a brewer he used to employ who hated cold break and took any step he could imagine to separate the wort from the cold break. He was eventually let go because every batch he brewed ended up being stuck (underattenuated) and nothing they did would rouse the yeast and coax it to properly attenuate the wort. Once they went back to the normal procedure which didn't separate cold break from the wort, the problems went away.

Seems like a funny way to solve a problem. The words 'cause' and 'effect' come to mind. It may very well have been that the steps taken to separate the wort added in a step that ruined things, rather than the separation itself causing the problems. Throwing out the baby with the bathwater, methinks.

 

[newguy]

I aerate my starters but there was a time that I wasn't aerating my wort at all. Every batch would 'stick' and would take on distinctly Belgian-type characters. Very unpleasant.

The micro & the problem was entirely due to the separation of the cold break. Every other procedure was and is identical to what they still do now but the problem has disappeared. The only extra thing that brewer was doing was waiting until the cold break settled out of the tank, then he pumped the clear wort over to a different fermenter where the yeast was pitched. Aeration took place via filtered high pressure air (from a compressor) on the way from the kettle to the first tank. The time spent in the first tank, prior to being pumped to a second, was maybe an hour at most. The separation from the cold break was definitely the issue....at least in that brewery. I've never separated my wort from the cold break so I can't comment on what would happen if I did. In this case, however, I think it's pretty clear that immediate separation from cold break is bad. For no chillers, where the wort remains in contact with the cold break for quite some time, perhaps the cold break is slowly reabsorbed...or a portion of it is.

 

[jonocarroll]

I aerate my starters but there was a time that I wasn't aerating my wort at all. Every batch would 'stick' and would take on distinctly Belgian-type characters. Very unpleasant.

That is what I would expect to happen with no aeration at all, but that's off-topic for here, since we are discussing the issue of good starter aeration and it's effect the requirement for wort aeration.

The micro & the problem was entirely due to the separation of the cold break. Every other procedure was and is identical to what they still do now but the problem has disappeared. The only extra thing that brewer was doing was waiting until the cold break settled out of the tank, then he pumped the clear wort over to a different fermenter where the yeast was pitched. Aeration took place via filtered high pressure air (from a compressor) on the way from the kettle to the first tank. The time spent in the first tank, prior to being pumped to a second, was maybe an hour at most. The separation from the cold break was definitely the issue....at least in that brewery. I've never separated my wort from the cold break so I can't comment on what would happen if I did. In this case, however, I think it's pretty clear that immediate separation from cold break is bad. For no chillers, where the wort remains in contact with the cold break for quite some time, perhaps the cold break is slowly reabsorbed...or a portion of it is.

This is also off-topic. My comment was merely that in order to understand why something happened, you need to look a lot further than just the details of what happened. Your statement 'I think it's pretty clear that immediate separation from cold break is bad.' is bad science, but I won't discuss it further right here. I will however provide a more humorous example...

 

[muckanic]

1. make starter - approx 1.5 L. I don't have a stir plate, so i use a 2L juice bottle covered with cling wrap and shake every time I walk past it.

It would probably be better to pour the contents roughly into another bottle about half a dozen times if you could be bothered. Also, a fibrous plug in the neck rather than the cling wrap would allow the starter to absorb more oxygen when it is not being agitated. Yes, this increases the risk of picking up a bug, but it's hardly as if anyone, stir-platers included, is talking about micro-filtered air in the first place.

One idea I have been toying with is to try and adapt a garden sprayer for starter growing duty, thanks to the ability to pump it up with pressurised air. The main problem of course is how to vent off the CO2 and trade it for O2. The safety relief valve will presumably stop the container from blowing up but it won't stop the CO2 pressure from impeding growth, so the sprayer would somehow or other need to be vented periodically. I guess the sequence would be vent CO2, pump air, shake, wait for O2 to be consumed (how long?), then vent again. This process is crying out for an automated approach, but then you might as well buy an industrial incubator!

 

[pdilley]

BTW: Head retention is fine

+1 for having the balls to be a mad scientist and push the knowledge base

 

[hazard]

I think this was one of the orignal articles outlining the process. in the experiemnt they do a 360 HL batch with 15ML of Olive oil, if i'm not mistaken that'd mean around 0.01ml for a regular 22L batch.

Someone please correct my math!

If you look at the original thesis, they state that they did several tests, ranging from 1 ml of oil per 67 Billion yeast cells to 1 ml of oil per 25 billion yeast cells. A smack pack is 100 billion yeast cells, so this implies about 1.5 to 4 ml of oil would be added for one smack pack. I think packs of dry yeast are a similar size, so this is still OK. Therefore Chappo appears to be spot on with 3 ml. They also added oil to starter 5 hours before pitching.

I am still to try this but keen to give it a whirl next time. All results in the thesis show that they achieved their aim - and the brewery packaged and sold the beer, so they were happy with results.

 

[JonnyAnchovy]

Any further updates Chappo??