Oxygenating starters?

[Dcpcooks]

[QUOTE="hopScottch, post: 8219648,

As long as the number of yeast is sufficient for the volume and OG of your beer, why do you need to oxygenated your beer if pitching from a starter?[/QUOTE]

O2 is important to yeast health. Even with your properly sized starter you will have cell division during the growth phase. Think about how much more yeast you have after a fermentation compared to how much you had at the pitch. You will see growth regardless of o2 levels but the overall health of the population will be greater with a good dose of o2.

Some of the signs that may suggest you didn’t have a healthy population for primary are stalled fermentations, increased ester production, long fermentations and/or higher levels of beer spoilage organisms surviving and reaching higher population numbers because they had more sugars available for a longer period of time that allowed them to get a foot hold in the batch.

A starter is a good step and oxygenating your wort is another good step. One doesn’t replace the other in the process.

If you’d like to read up on it the yeast book is very informative. My original brewing buddy from the start is brewing professionally now. I’ve learned a ton of things along the way from stopping by the brewery for a pint and some discussion. The biggest take aways have been yeast health and proper pitch rates along with proper cleaning and sanitation. They both go a long way to making great beers!

 

[mongoose33]

Dyqik's post stops short of answering a lingering question that I have yet to research. I would think that yeast from a 48 hr starter are viable (not necessarily exponentially growing). Perhaps they have exhausted the wort and cell division rate has slowed, but are nonetheless primed and "hungry" to metabolize more sugars. As long as the number of yeast is sufficient for the volume and OG of your beer, why do you need to oxygenated your beer if pitching from a starter?

Let me extend DCPCooks' excellent comment:

Yeast don't just stop reproducing once the starter goes quiet. They reproduce again in the fermenter, and as they go through what is known as the "lag" phase, they're getting ready to burst out.

And IMO DCPCooks is absolutely on target w/r/t the book "Yeast." Every time I pick that book up--and I've read it twice all the way through--I seem to learn something. Here's a comment from the book in the "lag phase" section:

You will not see any visible activity during the lag phase (hence its name) but this phase is a very important step in building new healthy cells for fementation. (page 67)

Then: The one nutrient yeast need, which is not present in wort due to boiling, is oxygen.....The cells need oxygen to produce important compounds, most significantly sterols, which are critical in yeast membrane permeability. (page 66).

Oxyenating starter wort is a good thing. Oxygenating the wort of the beer is a good thing, too.

FWIW: I have all four of the "ingredient" books: Yeast, Malt, Hops, and Water. Of the four, I've found "Yeast" to be the most useful in understanding what's going on. Second is "Water." Third is "Malt." Last is "Hops." YMMV, of course.

 

[day_trippr]

As mongoose33 knows I also hit my starters with O2 before putting them on the stir plate.
Having a metered O2 rig sitting right there it just seems crazy not to use it.

Out of the four I've only read Yeast - many times. Excellent resource...

Cheers!

 

[mongoose33]

As mongoose33 knows I also hit my starters with O2 before putting them on the stir plate.
Having a metered O2 rig sitting right there it just seems crazy not to use it.

Out of the four I've only read Yeast - many times. Excellent resource...

Cheers!

You're the only other one I know who does this, at least that I've seen on HBT.

 

[Minky]

You're the only other one I know who does this, at least that I've seen on HBT.

I also use a healthy dose of O2 in my starters, although I don't have a way of metering it. Whenever doing so, it's important to pitch the yeast into the starter after the O2 treatment because pure O2 can be toxic to the yeast.

 

[Azura]

I have the gear to infuse pure o2 into a stir plate starter, but never have. This is something that will probably never happen. Why? Because I don't have yeast performance issues.

 

[mongoose33]

I also use a healthy dose of O2 in my starters, although I don't have a way of metering it. Whenever doing so, it's important to pitch the yeast into the starter after the O2 treatment because pure O2 can be toxic to the yeast.

So you're number 3.

I've never heard that before about pure oxygen being toxic to the yeast. Is there a source for this? I ask because that's one of the things the LODO people recommend, i.e., pitch first, then oxygenate. I oxygenate, then pitch, but if there's a negative reaction by the yeast to the O2, I think people would want to know about it.

I sure would.

 

[mongoose33]

I have the gear to infuse pure o2 into a stir plate starter, but never have. This is something that will probably never happen. Why? Because I don't have yeast performance issues.

Maybe the yeast would do even better if the starter were oxygenated....

 

[MSK_Chess]

My understanding is that we use a stir plate not only to oxygenate the starter but to keep more yeast in suspension. If we are hoping for oxygen exchange on the starter surface due its motion then it would make sense to have a breathable cover to let air in and out. It would appear to me to defeat the purpose of a stirplate to put an air lock on a starter unless we were oxygenating the starter wort. The ultimate would be to oxygenate the starter and to have a breathable cover on a stir plate.

 

[Azura]

Maybe the yeast would do even better if the starter were oxygenated....

My beers finish within 2 points of where they are supposed to finish more than 95% of the time. This is using Beersmith and tweaked attenuation factors. Default attenuation factors are not completely reliable. The ester and phenol profiles are typically where I want them to be. This often means using less oxygen in the wort prior to pitching if the goal is to enhance them.

Really clean beers can happen with zero pure o2 and whatever o2 is infused by draining the kettle into the top of a sealed fermenter. However, this 'lazy technique' sometimes requires a higher pitch rate for neutral beers depending on the yeast strain.

Overall, I'm pretty stingy with the pure o2 compared to other brewers with a 5 micron stone and an internet connection. This didn't happen because I want to save money on Home Depot o2. I used to use a lot more of it per batch until I determined it wasn't necessary to make the beer I want to make. YMMV

 

[triethylborane]

It would appear to me to defeat the purpose of a stirplate to put an air lock on a starter

Yes, correct.

 

[day_trippr]

I also use a healthy dose of O2 in my starters, although I don't have a way of metering it. Whenever doing so, it's important to pitch the yeast into the starter after the O2 treatment because pure O2 can be toxic to the yeast.

Doubtful. Chris White in "Yeast" took wort to over 40ppm O2 with no observable fermentation issues...

Cheers!

 

[Minky]

So you're number 3.

I've never heard that before about pure oxygen being toxic to the yeast. Is there a source for this? I ask because that's one of the things the LODO people recommend, i.e., pitch first, then oxygenate. I oxygenate, then pitch, but if there's a negative reaction by the yeast to the O2, I think people would want to know about it.

I sure would.

A lot of the accepted wisdom on oxygenation is being reviewed and revised all the time as the big boys experiment with it, but there are still disagreements even among the commercial brewers. I've been very successful in adding a quick slug of O2 when beginning a starter, then using a stir plate.

This is from an article by Eric Watson, a commercial brewing consultant. Keep in mind, he's talking about constant aeration. These quotes are taken from a thread on The Brewing Network. It is from 2007, so the thinking on this may have evolved. http://thebrewingnetwork.com/forum/viewtopic.php?f=2&t=4000

"When oxygenating starters, you cannot use pure O2... the reason is that the uptake occurs too fast and without a dissolved O2 meter ($$$), you cannot tell when to stop. The way to properly do this one is to aerate using a high pressure aquarium pump, sterile air filter and a stainless steel aeration stone, all of which are readily available. It is virtually impossible to over-aerate using air, so you will avoid oxygen toxicity problems that will occur if trying to do this with pure oxygen." (Eric Watson; BeerTools.com)

He goes on to say, in another post in the thread, "...you should still O2 the starter, just do it for 30 seconds or so and BEFORE you pitch the yeast".

Jamil Zainisheff (sp?) also chimes in on the thread with his own variation on the theme. I highly recommend reading it, and if anyone has a link to other info on this subject that isn't 11 years old, I'm sure we'd all like to see it.

Using O2 in the wort itself is an entirely different matter, but I think I would still pitch after doing it.

 

[Azura]

The standard for pure o2 infusion specified by time to achieve a reliable ppm can be accomplished with a basic o2 pressure regulator which very few homebrewers own despite it being affordable. I would like to know who has one in this thread and why they didn't mention it earlier.

 

[hopScottch]

The standard for pure o2 infusion specified by time to achieve a reliable ppm can be accomplished with a basic o2 pressure regulator which very few homebrewers own despite it being affordable. I would like to know who has one in this thread and why they didn't mention it earlier.

Don't you mean an O2 flow meter (L/min) instead of a pressure regularor (psi)?

 

[Azura]

Don't you mean an O2 flow meter (L/min) instead of a pressure regularor (psi)?

Yes that thing. I don't have one. Do you?

 

[Minky]

Doubtful. Chris White in "Yeast" took wort to over 40ppm O2 with no observable fermentation issues...

Cheers!

I have been meaning to read that book. I would be interested in whether that 40ppm was achieved before pitching. My thinking on pitching afterward is that the yeast wouldn't be subject to a direct blast of pure O2, but would be pitched into wort that had the O2 already in solution.

 

[hopScottch]

No. I'm considering whether to add pure O2 to my process, which is why I'm following this thread. Just picked up this hobby a few months ago with only 4 brews under my belt and 3 kegged. I do have access to a gas flow meter I can "borrow". Isn't a flow meter the only means to quantify the absolute amount of O2 being delivered? Otherwise it's trail and error or guesswork.

 

[triethylborane]

I have been meaning to read that book. I would be interested in whether that 40ppm was achieved before pitching. My thinking on pitching afterward is that the yeast wouldn't be subject to a direct blast of pure O2, but would be pitched into wort that had the O2 already in solution.

Get the book, its a great resource and cheap @ $15.00

 

[Azura]

No. I'm considering whether to add pure O2 to my process, which is why I'm following this thread. Just picked up this hobby a few months ago with only 4 brews under my belt and 3 kegged. I do have access to a gas flow meter I can "borrow". Isn't a flow meter the only means to quantify the absolute amount of O2 being delivered? Otherwise it's trail and error or guesswork.

Not really. The standard o2 homebrew kit is a 5 micron stone, a filter, tubing and a valve that connects to a small red tank of Benzomatic o2 that isn't even food grade. Your 'ideal' o2 infusion time can be measured subjectively. Full blast is more than the o2 infusion standards with respect to time. The lighter infusion rates are closer to the time standard.

If you are just beginning to brew, this topic is less important than you think it is right now.

 

[MaxStout]

Even if you do monitor flow rate of O2, it's rather meaningless unless you can quantify how much O2 actually goes into solution. A significant percentage of what is aerated into the wort will rise to the top and escape. The best we can do as homebrewers is to aerate with an adequate volume of O2 to achieve a reasonable level of oxygenation. In short, you just have to make a guess.

 

[mongoose33]

A lot of the accepted wisdom on oxygenation is being reviewed and revised all the time as the big boys experiment with it, but there are still disagreements even among the commercial brewers. I've been very successful in adding a quick slug of O2 when beginning a starter, then using a stir plate.

This is from an article by Eric Watson, a commercial brewing consultant. Keep in mind, he's talking about constant aeration. These quotes are taken from a thread on The Brewing Network. It is from 2007, so the thinking on this may have evolved. http://thebrewingnetwork.com/forum/viewtopic.php?f=2&t=4000

"When oxygenating starters, you cannot use pure O2... the reason is that the uptake occurs too fast and without a dissolved O2 meter ($$$), you cannot tell when to stop. The way to properly do this one is to aerate using a high pressure aquarium pump, sterile air filter and a stainless steel aeration stone, all of which are readily available. It is virtually impossible to over-aerate using air, so you will avoid oxygen toxicity problems that will occur if trying to do this with pure oxygen." (Eric Watson; BeerTools.com)

He goes on to say, in another post in the thread, "...you should still O2 the starter, just do it for 30 seconds or so and BEFORE you pitch the yeast".

Jamil Zainisheff (sp?) also chimes in on the thread with his own variation on the theme. I highly recommend reading it, and if anyone has a link to other info on this subject that isn't 11 years old, I'm sure we'd all like to see it.

Using O2 in the wort itself is an entirely different matter, but I think I would still pitch after doing it.

I hope as we're all discussing this we remain in the spirit of trying to find out the answers, not getting into a p***ing match.

Now, that said... .....I read the link you specified (and thank you as I appreciate the willingness to back things up). I read all of it, and there's this quote as well:

"WORT AERATION: If possible, don't! The reason is that it is not the wort that needs the oxygen, it is the yeast. By oxgenating the wort instead of the yeast starter, it will cause an over production of cells due to the excessive oxygen presence. This then leads to the production of unwanted esters and higher alcohols that will compromise beer flavor.

I don't get this at all. It flies in the face of what I have read and believe to be true based on authorities like the White/Zainasheff book. And I would think that anything Zainasheff notes in a Yeast book copyrighted later than the 2007 thread would supercede what he might have said earlier.

Yes, of course it's the yeast that need the O2, but where are they going to get it? From the wort.

Further, it is well established that yeast continue to reproduce in the wort. We need them to do that, as there is no way there are enough yeast in a basic starter. To do that, they need oxygen or else you'll produce less vital yeast.

From White/Zainasheff, THE LAG PHASE, p66:

Once you pitch yeast into wort, it begins acclimating to the environment. Although you do not see any activity, the cells begin the uptake of oxygen, minerals, and amino acids (nitrogen) from the wort and build proteins from the amino acids...The one nutrient that yeast need, which is not present in wort due to boiling, is oxygen. During the lag phase, yeast cells rapidly absorb available oxygen from the wort. The cells need oxygen in order to produce important compounds, most significantly sterols, which are critical in yeast membrane permeability. It is important that you provide enough oxygen to the yeast at the beginning of fermentation.

[still in lag phase section] p67: The yeast produce minimal ethanol at this stage, so ester formation is not a concern. Yeast do not create esters until they first make an appreciable amount of alcohols.

I don't know what we learn from a battle of experts, but these guys have struck me as knowing what they're talking about. My experience dovetails with what they say. It's a view that is significantly at odds with the source you quoted, presuming O2 toxicity.

Now, again, we're all trying to figure this out. But it would appear to me that whatever was presumed about oxygen in wort has been superceded by other information.

 

[day_trippr]

Yes that thing. I don't have one. Do you?

[raises hand] Yup.

Ironically, I've been hooked up to the same Western Medical regulator/flow meter a couple of times in my life.

As for Eric Watson, I'd say his credibility just took an elevator ride to the basement.
How he could be a "brewery consultant" is beyond my comprehension, as he could only be correct in his views if every "authority" is wrong...

Cheers!

 

[Minky]

I hope as we're all discussing this we remain in the spirit of trying to find out the answers, not getting into a p***ing match.

I'm sorry if you thought I was trying to start a p**ing match. Remember this thread is about oxygenating starters, and I was trying to get across the idea that the starter DEFINITELY needs oxygen. I was not arguing against oxygen in the wort.

Now, that said... .....I read the link you specified (and thank you as I appreciate the willingness to back things up). I read all of it, and there's this quote as well:

"WORT AERATION: If possible, don't! The reason is that it is not the wort that needs the oxygen, it is the yeast. By oxgenating the wort instead of the yeast starter, it will cause an over production of cells due to the excessive oxygen presence. This then leads to the production of unwanted esters and higher alcohols that will compromise beer flavor.

Eric is probably sorry he put it in that way, but I think he was speaking from a purely theoretical standpoint trying to get across the idea that you don't want to pitch an under-oxygenated starter into your wort because the dissolved oxygen in the wort would dissipate before the sterol-deficient yeast had a chance to make use of it for reproduction. The "unwanted esters and higher alcohols" would result from this sterol deficiency. Presumably this happens when you pitch a vial directly without a starter.

Jamil had this to say:

"If you're not going to add O2 to the wort, you're going to need to pitch more yeast than if you do add O2. For me, I tried a number of batches of lagers (Ofest) with no O2 and more yeast to limit growth in the beer. A lot of people told me it wouldn't work, but the resulting beer was quite clean. Very clean. Too clean. The beer ended up seeming a little dull overall. I switched back to targeting some yeast growth in the beer. As the folks from Wyeast and White Labs will tell you, you must have some yeast growth or the beer just doesn't taste right."
​

Jamil said this about aerating starters:

"The way that works for me is to provide continuous aeration for the starter via either filtered air and/or a stir plate. This is pretty much error free, since you can't add too much O2 this way.

If you use pure O2, you need to be a bit more careful on your starter, you can hit it a few times with O2, but I wouldn't make it continuous. You're going to have to experiment to find a rate that works best for your yeast and your style of brewing."
​

Jamil certainly seemed to believe at that time that pure oxygen could cause problems in the starter, but maybe he has since backed off of that stance.


I don't get this at all. It flies in the face of what I have read and believe to be true based on authorities like the White/Zainasheff book. And I would think that anything Zainasheff notes in a Yeast book copyrighted later than the 2007 thread would supercede what he might have said earlier.

Yes, of course it's the yeast that need the O2, but where are they going to get it? From the wort.

Here again, just don't pitch an under-oxygenated starter. By the way, dry yeasts are ready to pitch because they have the proper sterol levels already. ​

Further, it is well established that yeast continue to reproduce in the wort. We need them to do that, as there is no way there are enough yeast in a basic starter. To do that, they need oxygen or else you'll produce less vital yeast.

I'm not arguing against oxygen in the wort.​

From White/Zainasheff, THE LAG PHASE, p66:

Once you pitch yeast into wort, it begins acclimating to the environment. Although you do not see any activity, the cells begin the uptake of oxygen, minerals, and amino acids (nitrogen) from the wort and build proteins from the amino acids...The one nutrient that yeast need, which is not present in wort due to boiling, is oxygen. During the lag phase, yeast cells rapidly absorb available oxygen from the wort. The cells need oxygen in order to produce important compounds, most significantly sterols, which are critical in yeast membrane permeability. It is important that you provide enough oxygen to the yeast at the beginning of fermentation.

[still in lag phase section] p67: The yeast produce minimal ethanol at this stage, so ester formation is not a concern. Yeast do not create esters until they first make an appreciable amount of alcohols.

I don't know what we learn from a battle of experts, but these guys have struck me as knowing what they're talking about. My experience dovetails with what they say. It's a view that is significantly at odds with the source you quoted, presuming O2 toxicity.

I think that the toxicity must come into play in a starter due to the small volume and lower gravity, and does not apply to the wort itself.​

Now, again, we're all trying to figure this out. But it would appear to me that whatever was presumed about oxygen in wort has been superceded by other information.

A lot can happen in 11 years. I know I have some catching up to do. ​

I put my response in the body of the quote, so please expand to see it.

 

[Minky]

Doubtful. Chris White in "Yeast" took wort to over 40ppm O2 with no observable fermentation issues...

Cheers!

I knew I had seen Chris & Jamil bringing up the issue of oxygen toxicity in starters somewhere else. This is from the AHA Forum - Ask the Experts. This is from 2013, so it's after their book was published.:

Greg in Virginia asks:
I use a stir plate for starters and get great results stepping up slurry amounts. Most all of the information available recommends good oxygen levels for starters as well as wort to build sterol reserves for cell walls. The question is whether I need to concentrate as heavily on wort oxygenation as the starter. How much benefit would there be in displacing the air in the starter vessel (Erlenmeyer flask) with pure O2, seal it with aluminum foil, and give it a vigorous stir cycle? After a short period of time, I would remove the foil and cover with a small beaker to allow my usual air transfer.

Additionally, I’ve reduced my starter OG to 1.025 - 1.028. I seem to get at least as much slurry as I did with gravities around 1.040. How low can the SOG go and still get good results in healthy, ready to go yeast?

Chris and Jamil answer:
If you are using a stir plate, then you most likely have adequate oxygen for healthy yeast growth. Additional oxygen may result in more yeast, but it may not as there may be some other factor that is limiting growth. Either way, there should be no harm from what you propose as long as the oxygen concentration does not become high enough to be toxic to the yeast.

I wouldn’t fret too much, as lower gravity starters can be better for yeast health. What you are finding in your higher gravity starter is that the yeast are using some of the sugars for growth and then just ferment the rest. This is why very large starters or low inoculation rates don’t grow much more yeast than properly sized starters. It isn’t a linear equation. In this case some factor other than sugar concentration is limiting growth.
​

It doesn't sound like what "Greg in Virginia" was doing would even come close to causing a problem, but Chris and Jamil do acknowledge that there is a potential for oxygen toxicity in starters.

My old brain doesn't always work right, but I KNEW I read that from a voice of authority! Onwards and upwards.

And CHEERS to you all.

 

[day_trippr]

Not exactly a metric - the statement is open ended.
But we already know you can go ~4X the recommended saturation level without issue, so there's hella head room...

Cheers!

 

[Christopher Darkly]

Aquarium pumps are cheap and you can just use an inline disc filter to sanitize the air and slip the tubing under your foil cap. Works with starters or your mead.