Ok, but if arguing a point scientifically, one must use the terms properly. correctly oxygenated wort will have no (or very little) o2 in solution once fermentation begins because it is used brr the yeast during reproduction (lag phase).
Aeration of starter, and NOT the wort - discussion.
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I see a theme in this thread.
Yeast is not the only place to get flavor in a beer. In fact many many styles call for very clean fermentation with little yeast character, including most American Ales. I wouldn't starve my yeast of O2 in order to get more "flavor" unless, esters are the particular flavor you're looking for. That said, many Belgian breweries under-pitch, and I wouldn't be surprised if they under-oxygenate too, in order to stress the yeast into more ester production.
Yeast is not the only place to get flavor in a beer. In fact many many styles call for very clean fermentation with little yeast character, including most American Ales. I wouldn't starve my yeast of O2 in order to get more "flavor" unless, esters are the particular flavor you're looking for. That said, many Belgian breweries under-pitch, and I wouldn't be surprised if they under-oxygenate too, in order to stress the yeast into more ester production.
There could be o2 molecules bonded elsewhere? Who can even measure the proper amount of a blast from a 02 tank? Who even takes into account the amount 02 already present in the starter?
Unless your judging by flavor and have done things multiple ways then it's just a respew of conventional brewing jargon. imho
So lets break away from the cookie-cutter brewing techniques for a moment.
Let's say you pitched a sizeable starter, could it possibly already contain enough o2?
Lets say you needed 200 billion cells and made a 2L starter that gave you 400 billion.
OH-NO overpitch!, your just dying to type it, I can tell...
But what if its a negligible overpitch? What if guaranteed a healthy ferment without 02 addition? I know it's a big what if if Jamil hasn't said so yet on a podcast. But would an overpitch balance out the lack of 02 for growth while still giving more desirable ethanol and ester flavors than a properly sized pitch into properly aerated wort??
What if we also considered some other downsides to using o2 besides being difficult to measure.
Like fire hazards. I gotta imagine having 02 tanks near a propane burner could very end badly. And what if you had a non-brewing related fire. I'd bet an 02 tank would pretty much ensure your entire building structure would burn down fast.
There is also the expense. I am pretty sure I have $300 tied up between tank/ regulator/ sterile filter, and stainless aerating wand. That could buy me a year's worth of brewing ingredients.
And then the general nuisances like an extra step on brew day. Additional risks for bacterial infection. Having to get the tank filled and hydro'd.
I've tried both methods and found no noticeable difference in the finished beer. Both beers had an OG of 1.038 and both were fermented with Y1469 which in each case was cultured up from 2nd generation slants.
The first beer had no extra aeration given to the starter other than when stepping up and the wort was aerated before pitching, this beer fermented down to 1.010 in 7 days. In the second beer the starter was aerated by pouring from one jug to another several times at pitching but no aeration was given to the wort and finished at 1.009 after 7 days. Final beer pH was almost identical at 3.98 and 4.02 and there was no apparent difference in taste from very similar recipes that could be attributed to the methods used. I think that in future unless I'm brewing very strong beers I'll just stick to aerating the starter.
The first beer had no extra aeration given to the starter other than when stepping up and the wort was aerated before pitching, this beer fermented down to 1.010 in 7 days. In the second beer the starter was aerated by pouring from one jug to another several times at pitching but no aeration was given to the wort and finished at 1.009 after 7 days. Final beer pH was almost identical at 3.98 and 4.02 and there was no apparent difference in taste from very similar recipes that could be attributed to the methods used. I think that in future unless I'm brewing very strong beers I'll just stick to aerating the starter.
Uhhh...what?
I don't use pure oxygen. The only time I mentioned it was in reference to getting enough oxygen into a small starter for a high gravity brew. I use an aquarium pump with filter.
Yes, over pitching will reduce the need for oxygen in the wort. Duh. It will also reduce the esters that give beer a lot of its flavor. The only way to get those esters back apparently would be to grossly over pitch I hear that also causes ester production.
Fwiw... I don't think that pitching an extra 200 billion cells into a beer that doesn't require a lot of esters would be a problem. I always err on the side of more yeast in my IPA and APA.
I am NOT married to any particular methods nor do I use a cookie cutter approach towards brewing. I have done plenty of research and have brewed enough beer to know what works and what doesn't for me. I invite everyone to start aerating they're disgusting flavored starters and pouring them into their beer as often as they like. I will continue decanting my starters and oxygenating my wort because my beer tastes really good and my method is streamlined and efficient just the way it is.
I guess my biggest argument with this method would be that you can't use a stir plate or even intermittent shaking while making your starter. You'd also have to keep it at lower temperatures than typical for a starter so that way the end product will taste like beer, not starter. But the whole point in a starter is to grow yeast not ferment beer so you'd be growing a lot less yeast and would need a much larger starter.
Seems to me like this is just a way to try to skip a step that someone thinks isn't important. Having enough oxygen is very important. Nuff said
I don't think that a original gravity that low really applies to this discussion. You don't need a whole lot of oxygen for healthy fermentation of that gravity. You probably had enough dissolved oxygen just from moving liquids around to get a decent fermentation on the on the non aerated one
It's weird that you give advice on aerating when your technique for aeration isn't even capable of reaching recommended 02 levels.
http://www.wyeastlab.com/hb_oxygenation.cfm
http://www.wyeastlab.com/hb_oxygenation.cfm
8ppm is fine for normal gravity and I add evoo in my high gravity.
It's weird that I'm being called out on under aerating when my method provides way more aeration than what I'm arguing against. I'm going to stop following this thread now since the discussion has moved to non sensible bs
It's weird that I'm being called out on under aerating when my method provides way more aeration than what I'm arguing against. I'm going to stop following this thread now since the discussion has moved to non sensible bs
FOLLOW-UP:
I promised follow-up after the UC Davis Brewing Micro course so here it is:
They recommend aeration in the starter and the wort since you are creating biomass in both places.
They recommend air, not O2, and suggested that splashing during transfer to the fermenter was more than adequate for 5 gallon fermentations.
And here was the real surprise; they recommend just pitching the vial/packet/pouch for 5 gallon batches and to not bother with a starter at all. I suspect this is a microbiologists focus on sanitation/contamination rather than on high quality beer but I have requested more info on this view.
Also, unless you are top cropping, do not bother with acid washes. When bottom cropping there is no real threat of Obeseum (as there is with top cropping) and acid washings real purpose is to fight Obeseum contamination. If you do acid wash, pitch the washed yeast immediately, it is not a storage technique.
I promised follow-up after the UC Davis Brewing Micro course so here it is:
They recommend aeration in the starter and the wort since you are creating biomass in both places.
They recommend air, not O2, and suggested that splashing during transfer to the fermenter was more than adequate for 5 gallon fermentations.
And here was the real surprise; they recommend just pitching the vial/packet/pouch for 5 gallon batches and to not bother with a starter at all. I suspect this is a microbiologists focus on sanitation/contamination rather than on high quality beer but I have requested more info on this view.
Also, unless you are top cropping, do not bother with acid washes. When bottom cropping there is no real threat of Obeseum (as there is with top cropping) and acid washings real purpose is to fight Obeseum contamination. If you do acid wash, pitch the washed yeast immediately, it is not a storage technique.
orangehero
Well-Known Member
What's the rationale?
paperairplane
Well-Known Member
So, 10 pages of experience, heresay, science, pseudo-science and common sense and what do we know:
1. You can make a starter, or not.
2. You can aerate a starter, or not.
3. You can pitch an aerated or not aerated starter into an aerated or not aerated wort.
4. You can use dry yeast and rehydrate, not rehydrate, make a starter or don't and pitch that into an aerated or non-aerated wort.
5. Wort can be aerated with O2, Air, both or neither.
6. Stir plates stir and shake plates shake and both, either or neither may or not work by incorporating air into a starter, but both probably keep yeast in suspension - which may or not be better.
7. Yeast reproduce aerobically and anaerobically - which may or not be desirable in your beer.
8. Underpitching is bad, except when it's good. Overpitching is hard to do, but might be bad.
9. Underaerating may be bad or it may be okay. Overaerating is bad, except not really.
10. Yeast are very fragile and must be cared for intently, except that almost any process or combination of processes will result in perfectly acceptable home brew beer.
1. You can make a starter, or not.
2. You can aerate a starter, or not.
3. You can pitch an aerated or not aerated starter into an aerated or not aerated wort.
4. You can use dry yeast and rehydrate, not rehydrate, make a starter or don't and pitch that into an aerated or non-aerated wort.
5. Wort can be aerated with O2, Air, both or neither.
6. Stir plates stir and shake plates shake and both, either or neither may or not work by incorporating air into a starter, but both probably keep yeast in suspension - which may or not be better.
7. Yeast reproduce aerobically and anaerobically - which may or not be desirable in your beer.
8. Underpitching is bad, except when it's good. Overpitching is hard to do, but might be bad.
9. Underaerating may be bad or it may be okay. Overaerating is bad, except not really.
10. Yeast are very fragile and must be cared for intently, except that almost any process or combination of processes will result in perfectly acceptable home brew beer.
That pure O2 is a powerful oxidizer and poisonous to eukaryotes in high concentrations. Without a dissolved oxygen meter it is very hard to monitor and control. They did not provide any research to support it. If I ever get setup with a scope I plan on doing some experiments because I have access to compressed air and O2....I do not have a meter though.
I will say that this seems to contradict information from Dr. Bamforth on the subject...he had no problem with O2 at saturation.
Bahlest
Thanks for the follow up.
I think this is a pretty easy experiment to run for those of you who brew ten gallon batches. Start with two vials of yeast. Make a starter for a 5-gallon batch out of one and direct pitch the other. Split the wort into two 5 gallon fermenters and let them rip side by side. Taste the finished beers and note any differences.
I would be interested to hear the results because making starters is one of the overall big "to do's" in homebrewing next to controlling fermentation temps. Seems like a big thing for UC Davis to be wrong on...
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