Do you still believe this? One of the last times this was discussed on the AHA forum, I got the impression that you no longer did.
Also, I remember you saying that friends of yours were conducting experiments with a DO meter. Did you ever find out what their results were?[/quote]
Yeah, I still believe it. I don’t recall the DO meter discussion, though. I have access to one now, so I may be able to run some tests.
OK… how is the starter wort oxidized?
“Wort” is poured into the container (in my case a 2000ml flask), yeast is added, and a foam (in my case) “plug” is inserted into the top of the flask to cover the opening. …this is not unlike a primary fermentor.
As the yeast starts to eat and multiply, it produces CO2, which - in short order - ends up creating positive pressure inside the flask (just like in a primary fermentor, with the airlock bubbling away…).
While the yeast is active and producing CO2, how is any O2 getting into the wort? …the positive pressure inside will leak CO2 to the outside, and not let anything in. Until - maybe - the yeast is finished.
Once finished, the yeast starts to shut down, and - if let stand for many(?) days - may eventually let O2 seep in, but with a glass flask, even then the interchange through the foam plug should be minimal.
I always questioned the “swirl the flask to oxygenate the wort” directions for the very reasons I just outlined - if anything you’re swirling in more CO2. Stirring the yeast up into the “food” - yes. Stirring in O2? …I don’t understand.
Am I wrong in my logic?
[quote=“Chris Roe”]OK… how is the starter wort oxidized?
“Wort” is poured into the container (in my case a 2000ml flask), yeast is added, and a foam (in my case) “plug” is inserted into the top of the flask to cover the opening. …this is not unlike a primary fermentor.
As the yeast starts to eat and multiply, it produces CO2, which - in short order - ends up creating positive pressure inside the flask (just like in a primary fermentor, with the airlock bubbling away…).
While the yeast is active and producing CO2, how is any O2 getting into the wort? …the positive pressure inside will leak CO2 to the outside, and not let anything in. Until - maybe - the yeast is finished.
Once finished, the yeast starts to shut down, and - if let stand for many(?) days - may eventually let O2 seep in, but with a glass flask, even then the interchange through the foam plug should be minimal.
I always questioned the “swirl the flask to oxygenate the wort” directions for the very reasons I just outlined - if anything you’re swirling in more CO2. Stirring the yeast up into the “food” - yes. Stirring in O2? …I don’t understand.
Am I wrong in my logic?[/quote]Your logic makes sense to me. I do think that many of us get too carried away with getting scientific with brewing on a home scale. I still try to keep it simple but end up getting caught up in stuff that makes more work but does not improve my beer. Seems like you would have to try pretty hard to oxygenate your beer with the small amount of wort in a starter. Besides the fact that the starter wort is added to your fresh wort you might be blasting with pure O2 or running a fish tank pump into just to get more O2.
These are things we like to banter about here just to have something homebrew to talk about.
How many of you have actually done a comparison? Tasted the starter wort? I’ve done both and for the starter sizes I use there was a detectable flavor impact. Now, if you want to pitch the whole thing, be my guest…it’s your beer and you get to decide. But unless you’ve actually tried it both ways and assessed the result, please don’t tell me it doesn’t matter.
Denny - I hope you didn’t read my question as being hostile - just trying to understand…
Are you certain the starter is OXIDIZED??? …I know in my field of work, a lot of people confuse “correlation” with “causation,” so I’m just trying to avoid that for myself and my understanding.
Because I am using straight DME for my starter, I fully expect that my starter wort would have a different taste than my “beer” wort. With that said, yes, I can see if I added 20+% “other” liquid (1 gal +) to a 5 gal batch, the “other” liquid could start to impart other flavors, but I would imagine that nearly ANY liquid you added in that quantity would change the flavor of the finished beer.
In your experience, where do you believe the oxidation comes in? Could it come in at the “crash” phase in the fridge? …cooling temps would lower pressure inside the flask, causing outside air to be pulled in through the plug. O2 could come in that way, but - how long does it take wort to oxidize? If folks dropped the temp of the wort significantly prior to pitching, then mixed the solution vigorously (thereby mixing in the new O2 into the wort), that would be a way to get oxidation I guess, but - again, how long would that wort have to sit before it became oxidized?
[quote=“Chris Roe”]Denny - I hope you didn’t read my question as being hostile - just trying to understand…
Are you certain the starter is OXIDIZED??? …I know in my field of work, a lot of people confuse “correlation” with “causation,” so I’m just trying to avoid that for myself and my understanding.
Because I am using straight DME for my starter, I fully expect that my starter wort would have a different taste than my “beer” wort. With that said, yes, I can see if I added 20+% “other” liquid (1 gal +) to a 5 gal batch, the “other” liquid could start to impart other flavors, but I would imagine that nearly ANY liquid you added in that quantity would change the flavor of the finished beer.
In your experience, where do you believe the oxidation comes in? Could it come in at the “crash” phase in the fridge? …cooling temps would lower pressure inside the flask, causing outside air to be pulled in through the plug. O2 could come in that way, but - how long does it take wort to oxidize? If folks dropped the temp of the wort significantly prior to pitching, then mixed the solution vigorously (thereby mixing in the new O2 into the wort), that would be a way to get oxidation I guess, but - again, how long would that wort have to sit before it became oxidized?[/quote]
Hey Chris, no hostility from you and none directed toward you. Yes, I’m 100% certain my starter tasted oxidized. I tasted the wort prior to crashing it in the fridge, so I detected oxidation right off the stir plate. Unfortunately, I didn’t do a stringent blind triangle on the finished beer, so maybe I’m fooling myself, but I thought I could detect the same oxidized, stale taste in the beer (although to a much lesser extent) as I could in my starter. This was a 3 qt. starter for 5.5 gal. batch of my 1.073 70 IBU Rye IPA.
[quote=“Denny”][quote=“Chris Roe”]Denny - I hope you didn’t read my question as being hostile - just trying to understand…
Are you certain the starter is OXIDIZED??? …I know in my field of work, a lot of people confuse “correlation” with “causation,” so I’m just trying to avoid that for myself and my understanding.
Because I am using straight DME for my starter, I fully expect that my starter wort would have a different taste than my “beer” wort. With that said, yes, I can see if I added 20+% “other” liquid (1 gal +) to a 5 gal batch, the “other” liquid could start to impart other flavors, but I would imagine that nearly ANY liquid you added in that quantity would change the flavor of the finished beer.
In your experience, where do you believe the oxidation comes in? Could it come in at the “crash” phase in the fridge? …cooling temps would lower pressure inside the flask, causing outside air to be pulled in through the plug. O2 could come in that way, but - how long does it take wort to oxidize? If folks dropped the temp of the wort significantly prior to pitching, then mixed the solution vigorously (thereby mixing in the new O2 into the wort), that would be a way to get oxidation I guess, but - again, how long would that wort have to sit before it became oxidized?[/quote]
Hey Chris, no hostility from you and none directed toward you. Yes, I’m 100% certain my starter tasted oxidized. I tasted the wort prior to crashing it in the fridge, so I detected oxidation right off the stir plate. Unfortunately, I didn’t do a stringent blind triangle on the finished beer, so maybe I’m fooling myself, but I thought I could detect the same oxidized, stale taste in the beer (although to a much lesser extent) as I could in my starter. This was a 3 qt. starter for 5.5 gal. batch of my 1.073 70 IBU Rye IPA.[/quote]
I’ve noticed the same thing in my starters, Denny, definitely an oxidized taste (among other not so pleasant flavors).
Here’s the thing: as long as a starter is fermenting fast enough, it’ll create enough CO2 to displace all the oxygen and other gases in the starter flask (note I said displace, there really isn’t any positive pressure inside the container- not unless it’s corked solidly or has a full airlock on it). Once fermentation has slowed to a crawl or stopped, the CO2 in the flask will eventually dissipate and be replaced in large part with other gases (including oxygen). CO2 will tend to remain in the flask in higher concentration, being the heaviest gas, but it will eventually reach equilibrium with the outside air. If the flask is on a stir plate during this time, there is enough movement of the wort to keep the CO2 inside the flask agitated, thus accelerating the displacement of CO2 into the outside atmosphere. In my opinion, this is probably the point where the bulk of oxidation occurs in a stirred starter.
I’ve not tasted my starters. Maybe I’ll do that next time I make one 
I don’t have much experience, not enough to be able to say what’s right or wrong anyway. I’ve done it both ways but in two very different beers, and I must say I’m no beer judge so I couldn’t tell you if it made a difference.
I’d say you’d need to make two starters, brew 10 gallons of the same beer, pitch the whole starter into one 5 gal batch and decant then pitch the other starter into the other batch.
I’d offer to try, but again my palate isn’t exactly trained for this sort of thing. Also seems like a lot of effort, so I’ll just defer to those with more experience 
Flavor impact on the finished beer Denny? If so I have no problem believing its true. I just keep trying to keep it simple as long as I’m happy with my beer. Almost no one else drinks it so the only judge is me. However if I can make it better, why not. 99% of my beer are 20 gallon batches so a starter or slurry is the only option. Next time I will try to split the starter and do one decanted the other not, do ten gallons with one and ten the other then report back. This means I might have to actually write stuff down though.
Saturday I pitched the whole starter. Is my beer ruined? :lol:
