Confused about starters...

I've been reading about starters for two days now, listened to the BrewStrong show about them, and I guess I have more questions than I did before I started...

The consensus seems to be that one should use a stir plate, and decant.

Now, I'm not too lazy to build a DIY stir plate, but I'm wondering if it actually might be better to use simple starters (no shaking or stir plate) combined with pitching the whole starter. Kaiser among others has touted the benefits of pitching starters at high krausen. So my questions are (and there are many, I apologize...)

1) Why force the yeast to go dormant by letting them eat all the available sugar and refrigerating them for a day before decanting and pitching? Is it not better to continuously step them up (e.g. pitch 2-3 quart starter right into the 5 gallon wort)?

2) Why continuously aerate the wort if the yeast will propagate themselves just fine in an open container? Is it just for speed, or is it better for the finished beer in some way?

3) Many people say the starters are oxidized so it's bad to pitch them. How can a simple starter at high krausen be oxidized? I thought this doesn't happen until fermentation is over?

4) Many people say that the starter wort tastes bad... but to me it doesn't taste any different than beer at that stage of fermentation. It's got a ton of suspended yeast, it's flat, and it's green as green can be... but it would eventually taste just fine given enough time right?

5) Aaand finally, do some yeast respond better to stir plates, while some respond better to open fermentation, and some to closed (air lock on the starter)? Anybody know what's best for each strain, or is there a way to tell?

I do my starters at room temp so there may be off flavors in there I dont want in my beer. I don't think O2 is a problem because the beer should be pretty O2 free with the airlock on there, even if constantly agitated with a stir bar. I ran an airlock on my stirplate fwiw.

Also, if you are stepping up a starter you would either have to decant or progress to larger and larger containers.

There seems to be a lot less krausen using a stir plate which means less chance of a mess. This keeps SWMBO happy too. Fermentation also seems to finish faster because all the yeast is in suspension and not packed down on a yeast cake.

Heck, I just make a little wort using DME, boil it for 10 minutes or so...cool it fermentation temp and pitch yeast. usually from some washed yeast I have saved. Then after a day or two I throw the entire rig in whatever I am brewing. More beer is better. I usually do my starters in clear wine bottles. One bottle if under 1.060 and two if over.

1) Why force the yeast to go dormant by letting them eat all the available sugar and refrigerating them for a day before decanting and pitching?

refrigerating the starter gets the yeast out of suspension allowing you to pour off the bad starter beer and keep the yeast. the yeast will stay active for 24-48 hours after eating all the sugar. that way they are healthy and hungry for new sugar.

2) Why continuously aerate the wort if the yeast will propagate themselves just fine in an open container? Is it just for speed, or is it better for the finished beer in some way?

yeast grow easiest in an oxygen rich environment. the less stress you put on the yeast the better. by covering the container you are preventing other organism from getting into your starter.

3) Many people say the starters are oxidized so it's bad to pitch them. How can a simple starter at high krausen be oxidized? I thought this doesn't happen until fermentation is over?

oxidation can happen at any time. aerating after the boil before the wart temp gets below about 80 will oxidize it. continuously aerating your starter (which is a good idea) will speed growth and oxidize the starter. its best to put the starter in the fridge to get the yeast out of suspension and then gently pour off the starter beer. then add a little pre-boiled water and shake then pour into your wart.

4) Many people say that the starter wort tastes bad... but to me it doesn't taste any different than beer at that stage of fermentation. It's got a ton of suspended yeast, it's flat, and it's green as green can be... but it would eventually taste just fine given enough time right?

no because the starter is oxidized it will develop a cardboard aroma and taste over time.

5) Aaand finally, do some yeast respond better to stir plates, while some respond better to open fermentation, and some to closed (air lock on the starter)? Anybody know what's best for each strain, or is there a way to tell?

all yeast work the same way. some Belgian style beers are traditionally brewed in open fermenters but that is due to tradition. at the time people didn't know about yeast or other microorganisms. to prevent oxidation and contamination all fermenters should be sealed with some sort of pressure release valve (an airlock)

I have been saving (freezing) extra wort [last runnings] from my batches. And I am planning to brew this weekend with some washed WY1728 yeast.

So as a followup question - what is the recommended SG of a starter for a beer under 1.060? 1.030-ish?

the OG is assumed to be 1.040 for all starters unless other wise stated.

I should clarify, when I said "open container" i really meant one that is covered loosely with foil. It's open in the sense that air can get in and out, but things cannot fall into it. Plus I'm only talking about starters, I would not ferment beer in anything that didn't have an airlock.

TipsyDragon said:

yeast grow easiest in an oxygen rich environment. the less stress you put on the yeast the better. by covering the container you are preventing other organism from getting into your starter.

oxidation can happen at any time. aerating after the boil before the wart temp gets below about 80 will oxidize it. continuously aerating your starter (which is a good idea) will speed growth and oxidize the starter. its best to put the starter in the fridge to get the yeast out of suspension and then gently pour off the starter beer. then add a little pre-boiled water and shake then pour into your wart.

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So I would assume that if you were to make a simple starter, then the best way to do it would be to NOT use a stir plate? Perhaps this would minimize oxidation?

Which I guess begs another question, if the goal is to create a starter that can be pitched whole, at high krausen, would it be beneficial to use an airlock? Is it a bad idea to use the aluminum foil cover to allow it to "breath"/oxidize?

scone said:

So I would assume that if you were to make a simple starter, then the best way to do it would be to NOT use a stir plate? Perhaps this would minimize oxidation?

Which I guess begs another question, if the goal is to create a starter that can be pitched whole, at high krausen, would it be beneficial to use an airlock? Is it a bad idea to use the aluminum foil cover to allow it to "breath"/oxidize?

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for a starter you want to oxidize it. it will make the yeast grow better but wreck the taste of the starter which is why you don't add the liquid to the beer. using aluminum foil is AOK. airborn microbes will not be able to get past it.

I'm still not convinced...

I'm not trying to be a hardass about this, but I'm really curious about the exact mechanics of oxidation in starters and their effects on beer. Actually the more I read about, the more curious I am.

For starters, I am assuming that oxygenating the beer (by aerating it) is NOT the same thing as oxidizing the beer. Oxidizing takes time, and involves a lot of chemical reactions. When you aerate, you are only dissolving oxygen. What happens to that dissolved oxygen is what I'm really trying to understand here.

You are saying that an oxygenated starter will cause the finished beer to become stale. What I've been reading leads me to believe that oxidation (as it pertains to flavor) is a chemical reaction between free oxygen radicals, and other stuff in the beer, and it's effect on the flavor of the beer takes time (weeks to months).

So can a starter really be irreversibly oxidized in such a short amount of time? And if not, then won't the extra oxygen in the starter be used by the yeast as it multiplies in the wort? Thus pitching a highly aerated starter shouldn't have any oxidative affect on the finished beer, since the yeast will use it all up right? Am I making sense?

It's not so much that the oxygenated starter will cause the beer to be oxidized as that the starter wort is oxidized and you don't want that in your nice fresh wort. I know this from bitter experience!

I am assuming that oxygenating the beer (by aerating it) is NOT the same thing as oxidizing the beer.

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Correct. I think some people are confusing terms.

Another reason for using a stirrer, this keeps the yeast in suspension and maximizes the exposure to nutrients.

I don't leave my flasks open to the outside air like some people do (with the foam stopper). I inject O2 into the wort for 30 seconds and cap off with foil. I put it on the stirplate the night before brewday and pitch everything. Just like a regular beer that has been fully oxygenated upon pitching, the yeast will consume the O2 well before oxidation can happen. I suppose if you run a stirplate for 48 hours with a foam stopper, you'd really want to chill and decant. From my perspective, the stirring action keeps all the yeast in suspension which helps the growth.

Bobby_M said:

I don't leave my flasks open to the outside air like some people do (with the foam stopper). I inject O2 into the wort for 30 seconds and cap off with foil.

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Do you worry that the foil is not airtight? Is there a reason you aren't using an airlock? Also, do you happen to know what ppm O2 you are getting with the 30 seconds? Also, do you still aerate the wort before pitching? Sorry for the multitude of questions...

I don't worry about airtight because I expect a constant positive prossure of CO2 in the flask. I don't like a bung with airlock because it doesn't protect the top lip of the flask from getting contaminated. I suppose I could use a carboy cap but never tried it. I boil the starter with the foil on so it steam sanitizes. I honestly have no idea what PPM of O2 I'm getting. It's a wild assed guest. Yes, I still provide O2 in the full batch, 60 seconds there, because I still want more yeast growth.

I boil 1/2 cup Xtra light DME in a flask with 1500 ml spring water with a tin foil cover, chill to room temp, displace the interior of the flask with O2, turn on the stir plate and pitch from a slant. Within 48 hours I have a noticeable change in color and texture of the wort. I then turn off the stir plate and let it set for up to 48 hours thru brew day. At pitching time I decant the beer off the top of the starter, swirl vigorously, capture the stir magnet with a magnet on the outside of the flask and pitch. I don't use a lock because it needs a free gas exchange. I'm trying to grow yeast here not make beer.

May not be exactly proper, but I have had no problems so far.

Don't worry about oxidation. You're biggest concern is making yeast with a starter, not beer. If you're worried about that 1 or 2 liters being oxidized and affecting your 5+ gallons of beer then cold crash you starter, decant, and then add the yeast to your beer.