Author Topic: Yeast Starter  (Read 3486 times)

Offline Pawtucket Patriot

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Re: Yeast Starter
« Reply #15 on: January 12, 2011, 10:48:00 AM »
+1, richardt. That's been my experience too. I really only decant starter wort when I'm brewing very pale lagers and only after 24-48 hours of cold crashing.
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Offline hokerer

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Re: Yeast Starter
« Reply #16 on: January 12, 2011, 10:57:00 AM »
I assume this would apply to pitching WL tubes straight from the fridge as well??  I've always just "read the directions" which say to warm to 70-75.


You're not doing yourself any favors just pitching the tubes straight (unless your brew is very low gravity).  To make better beer, you should be making starters.
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Offline tomsawyer

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Re: Yeast Starter
« Reply #17 on: January 12, 2011, 01:10:15 PM »
FWIW, I've done it both ways and now I'm straight form the fridge and into the beer.  The temp shock theory is outdated and has been disproved.  The current theory is that the yeast will start using up their glycogen reserves once they warm up and become active and you want that to happen in the beer, not before the yeast gets there.  I find I get far better yeast performance by pitching cold.  I'd encourage you to try it a few times and compare for yourself.  At the very least, there's no downside.

Denny, why would warming yeast from 4C to 20C prior to pitching cause them to start using glycogen reserves?  Theres no sugar so I don't think they would "spring into action".  If you let a culture use up all the sugar in a starter, its going to settle out and be dormant until theres more substrate whether the temp is 20C or 4C.  I think we're confusing the situation with dry yeast where you're rehydrating them with water and you don't want to leave them out of a wort for more than 20min.

On the other hand I don't think  theres any real reason to warm them first either, tif there is such a thing as shock it would be going from warm to cold.

I kind of like "waking the yeast up" by feeding them some sugar prior to pitching, that way I get the best of both worlds.  I get rid of any off-flavored beer from the starter, and I get them going with the small feeding a few hours prior to pitching.   Is it necessary, no.

I assume this would apply to pitching WL tubes straight from the fridge as well??  I've always just "read the directions" which say to warm to 70-75.


You're not doing yourself any favors just pitching the tubes straight (unless your brew is very low gravity).  To make better beer, you should be making starters.

Maybe he's making a 3gal batch of ale, in which case no starter is necessary.  I asked this question of the experts, since the one sells tubes of yeast as pitchable for 5gal, and the other has the Mr Malty calculator that tells us that a tube isn't enough for a 1.030 beer.  No word back, but I'm hopeful of a discussioni.


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Re: Yeast Starter
« Reply #18 on: January 12, 2011, 01:15:45 PM »
I assume this would apply to pitching WL tubes straight from the fridge as well??  I've always just "read the directions" which say to warm to 70-75.


Well I was actually referring to a low gravity ale or making a starter.  I usually let my WL tube warm before pitching into the starter.
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Offline tomsawyer

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Re: Yeast Starter
« Reply #19 on: January 12, 2011, 01:19:16 PM »
I concur with the need to let the starter settle out for a couple of days.  If you rush it and decant, you are selecting for the faster floccing yeast which may or may not be what you want to do.  Wouldn't be too hot for a wheat yeast where you are wanting the slow floccers.
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Offline tschmidlin

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Re: Yeast Starter
« Reply #20 on: January 12, 2011, 02:01:04 PM »
FWIW, I've done it both ways and now I'm straight form the fridge and into the beer.  The temp shock theory is outdated and has been disproved.  The current theory is that the yeast will start using up their glycogen reserves once they warm up and become active and you want that to happen in the beer, not before the yeast gets there.  I find I get far better yeast performance by pitching cold.  I'd encourage you to try it a few times and compare for yourself.  At the very least, there's no downside.

Denny, why would warming yeast from 4C to 20C prior to pitching cause them to start using glycogen reserves?  Theres no sugar so I don't think they would "spring into action".  If you let a culture use up all the sugar in a starter, its going to settle out and be dormant until theres more substrate whether the temp is 20C or 4C.  I think we're confusing the situation with dry yeast where you're rehydrating them with water and you don't want to leave them out of a wort for more than 20min.
Just because they are not fermenting doesn't mean they're not doing anything.  And what they're doing, they do faster at 20C than at 4C, which can potentially use up glycogen reserves. :)

On the other hand I don't think  theres any real reason to warm them first either, tif there is such a thing as shock it would be going from warm to cold.
There certainly is such a thing as heat shock, but based on people's experience here it is not clear if it is relevant when moving yeast from fridge to pitching temps.  There are entire classes of proteins that respond to heat and cold shock.  Cold shock is relevant when moving warm yeast to lager temps, the response can be induced when moving to 10C (50F). ;)
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Re: Yeast Starter
« Reply #21 on: January 12, 2011, 02:41:31 PM »
I assume this would apply to pitching WL tubes straight from the fridge as well??  I've always just "read the directions" which say to warm to 70-75.


Well I was actually referring to a low gravity ale or making a starter.  I usually let my WL tube warm before pitching into the starter.

Ahhh Ok, sorry about that then, carry on
Joe

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Re: Yeast Starter
« Reply #22 on: January 12, 2011, 02:53:44 PM »
Denny, why would warming yeast from 4C to 20C prior to pitching cause them to start using glycogen reserves?

Please see Tom Schmidlin's answer...he's the yeast expert!
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Re: Yeast Starter
« Reply #23 on: January 12, 2011, 03:07:09 PM »
Tom, using your logic regarding reserve utilization, the minute a starter culture runs low on sugar in the wort, it begins using up its glycogen reserves.  I don't think this is the case.  The cells become dormant, their metabolism slows and the utilization of reserves is already minimized even without the further slowing by cold temps.  I don't think viability or health is affected by a few hours at room temp in a beer environment, if it were then we wouldn't be harvesting viable yeast off the bottoms of fermentors after days of this kind of environment.

Heat shock is a phenomenon that involves subjecting an organism to temps above its normal or optimal environment.  Since a yeast's optimal temp is well above our typical fermentation temp, or even most room temps, I don't think we are going to find heat shock proteins being expressed in a culture pitched in a properly cooled wort.

Bottom line, yeast is pretty tough stuff and I'm not sure there's a "best way" here thats head and shoulders above the others.
« Last Edit: January 12, 2011, 03:08:48 PM by tomsawyer »
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Offline tschmidlin

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Re: Yeast Starter
« Reply #24 on: January 12, 2011, 03:59:37 PM »
Tom, using your logic regarding reserve utilization, the minute a starter culture runs low on sugar in the wort, it begins using up its glycogen reserves.  I don't think this is the case.  The cells become dormant, their metabolism slows and the utilization of reserves is already minimized even without the further slowing by cold temps.  I don't think viability or health is affected by a few hours at room temp in a beer environment, if it were then we wouldn't be harvesting viable yeast off the bottoms of fermentors after days of this kind of environment.
As the yeast detect the sugar is running low they actually generate more glycogen to build their reserves.  Once all of the sugar is gone and their ATP reserves are depleted they have to begin using the glycogen to generate more, there's really no other choice.  Protein synthesis doesn't stop, even the process of flocculating requires protein synthesis.  Living requires energy, and that's what the glycogen is there for.  If you warm the yeast it will begin synthesizing proteins to help it survive in its present environment.  If that environment is a warm spent starter then that is what the yeast will protect itself from, including generating ADH2 to begin using the ethanol as a carbon source.  That will take energy.  Unfortunately, ADH2 only converts ethanol to acetaldehyde (and it is specifically not synthesized in the presence of glucose).  What you want when you pitch your yeast into beer is ADH1 to convert acetaldehyde into ethanol, the final step in the relevant fermentation pathway.  So when you pitch your re-warmed starter into wort, the yeast have to generate ADH1 and at the same time remove the ADH2.  And that is only one example, there are bound to be many more proteins that the yeast need to survive in a an ethanol solution as opposed to wort.

That being said, I'm not saying it is definitely enough to deplete all of their glycogen reserves or even to have more than a marginal affect, especially after just a few hours.  But it seems pretty clear to me that from that perspective it is a step in the wrong direction.  There may be benefits from pitching warm that offset it, I haven't tested that either.

As for harvesting after several days, there will be stronger cells and weaker cells and you can pitch a lot to make sure there is sufficient amount of healthy yeast.  But that doesn't mean it's optimal to keep the yeast under beer.  :)


Heat shock is a phenomenon that involves subjecting an organism to temps above its normal or optimal environment.  Since a yeast's optimal temp is well above our typical fermentation temp, or even most room temps, I don't think we are going to find heat shock proteins being expressed in a culture pitched in a properly cooled wort.
My point about heat shock was in reference to your comment "if there is such a thing as shock", because there is such a thing as shock.  But I may have misinterpreted what you meant.  Anyway, I haven't read any research for differential expression when moving yeast quickly from cold to warm temperatures relevant to fermentation.

Bottom line, yeast is pretty tough stuff and I'm not sure there's a "best way" here thats head and shoulders above the others.
Agreed.  I think Denny's point is that pitching cold works just as well and gives you one less thing to worry about on brew day.
Tom Schmidlin

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Re: Yeast Starter
« Reply #25 on: January 12, 2011, 07:47:18 PM »
Yeast can survive in beer at a refrigerated temp for some months, lets say two although I've kept them longer and still made viable starters.  Theres a general biochem rule of thumb that enzyme activity doubles for every 10C increase in temp.  Going from 4C to 24C (generous, this time of year its closer to 14C in my basement), we'd see two doublings of activity.  Thats a 4x increase in the rate of metabolism of glycogen.  So we should at least have two weeks at room temp before our average yeast runs completely out of stored carbs and starves to death.  Granted, they'd be darned weak after a week, but all we're needing is a few hours so I think the fact that metabolism is higher at room temp is insignificant as a practical matter.  I'm also not that certain there's a heck of a lot of protein synthesis going on in a mature, dormant yeast cell.  Its kind of the nature of dormancy, that a cell shuts down most synthesis activities and only keeps maintenance metabolism active.

Think we've made the OP sorry he asked the question yet?

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Offline rbclay

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Re: Yeast Starter
« Reply #26 on: January 12, 2011, 08:47:52 PM »
Can we back up a second to the original question? I am not as experienced as most on here but I definitely understand the thread so far, and I believe the OP is probably a relatively new brewer. Although the details describing crash cooling, etc. that have been discussed are all good, I like the simplicity, and results, of my system. May be a little easier for a newer brewer.

I can't always brew on a schedule that allows me to make a starter 3-4 days in advance. More often I find myself having a day or so "notice" and can make a starter which I will pitch 12-18 hours after starting it. I based this on MrMalty. No decanting. No crash cooling. Just swirl and pitch. My starter is a few degrees higher than room temp. (Set it on the furnace or in the upstairs bedroom- some warm location). I must note that I only make ales thus far. I make relatively small starters. 750ml. Basically doubling my smack pack count. I am pitching my starter into wort that may be as much as 10F-15F cooler, but that is not an issue as verified earlier in this thread- and also verified by my experiences.

I also brew 2 or 3 batches in a row with the same yeast. In effect, each batch is a starter for the next. I also do this as "simply" as possible. I brew when I know the first batch is ready to be racked- when primary is done. And I pitch the new chilled wort directly on the yeast cake. No washing, etc. I started this as an experiment and I am always willing to improve my practices, but I don't see any reason to change what I'm doing. And it gives me a great excuse to brew- "but honey, the yeast is calling! I need to brew today!" I know this procedure has improved my beers. And isn't that what we all strive for- making better beer?!?
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Offline maxieboy

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Re: Yeast Starter
« Reply #27 on: January 12, 2011, 09:16:09 PM »
Can we back up a second to the original question? I am not as experienced as most on here but I definitely understand the thread so far, and I believe the OP is probably a relatively new brewer. Although the details describing crash cooling, etc. that have been discussed are all good, I like the simplicity, and results, of my system. May be a little easier for a newer brewer.

I can't always brew on a schedule that allows me to make a starter 3-4 days in advance. More often I find myself having a day or so "notice" and can make a starter which I will pitch 12-18 hours after starting it. I based this on MrMalty. No decanting. No crash cooling. Just swirl and pitch. My starter is a few degrees higher than room temp. (Set it on the furnace or in the upstairs bedroom- some warm location). I must note that I only make ales thus far. I make relatively small starters. 750ml. Basically doubling my smack pack count. I am pitching my starter into wort that may be as much as 10F-15F cooler, but that is not an issue as verified earlier in this thread- and also verified by my experiences.

I also brew 2 or 3 batches in a row with the same yeast. In effect, each batch is a starter for the next. I also do this as "simply" as possible. I brew when I know the first batch is ready to be racked- when primary is done. And I pitch the new chilled wort directly on the yeast cake. No washing, etc. I started this as an experiment and I am always willing to improve my practices, but I don't see any reason to change what I'm doing. And it gives me a great excuse to brew- "but honey, the yeast is calling! I need to brew today!" I know this procedure has improved my beers. And isn't that what we all strive for- making better beer?!?

You're probably overpitching on the batches in a row. From MrMalty:

"You might ask why not pitch as much yeast as possible? There is also an upper limit to how much yeast you should add. Logsdon says, “I try to stay within 20% of my ideal pitch rate and I prefer to slightly under pitch rather than over pitch. This causes more cell growth, more esters, and better yeast health. Over pitching causes other problems with beer flavor, such as a lack of esters. Changes in the flavor profile are noticeable when the pitch rates are as little as 20% over the recommended amount.”

Try using the slurry function in the calculator when pitching yeast from a previous batch. Happy brewing.
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Offline rbclay

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Re: Yeast Starter
« Reply #28 on: January 12, 2011, 10:18:22 PM »
You are probably right, however I am in the camp of it is better to over than under pitch. Looking at that calculator it says to pitch 65ml of a thick slurry into a 1060 wort. Maybe I am missing something and I should read the entire Yeast book, but 65ml is about half a smack pack?!? How is that enough yeast? Even with a much more concentrated amount of cells in a slurry, that volume just doesn't seem right. But, I haven't tried it and eveything else I have tried from MrMalty has worked so...

I like the feeling that the "pitching on a cake" procedure is rather simple. Taking the time to actually measure the volume of slurry is an additional step that seems unnecessary when what I have done so far is working well. My last 3 step "batch" was a Dark Mild, Brown Porter and finally an EBW, all with NeoBrittania. Damn fine Mild, porter is bottle conditioning now, EBW just finishing primary. All I know is the blow off from the EBW was HUGE. It went from 1.104 to 1.046 in 3 DAYS. And is at 1.032 after a month. That attenuation rate is right in line with the first 2 batches. Not exactly in line with what the strain guidelines say, but it consistent with the numbers in my system. Only time will tell. 2012 Nationals?!?

I probably could pitch 2 or 3- 5 gallon batches with the yeast from the EBW... mmmm.... that would be this weekend....

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Offline tschmidlin

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Re: Yeast Starter
« Reply #29 on: January 12, 2011, 10:45:46 PM »
Yeast can survive in beer at a refrigerated temp for some months, lets say two although I've kept them longer and still made viable starters.  Theres a general biochem rule of thumb that enzyme activity doubles for every 10C increase in temp.  Going from 4C to 24C (generous, this time of year its closer to 14C in my basement), we'd see two doublings of activity.  Thats a 4x increase in the rate of metabolism of glycogen.  So we should at least have two weeks at room temp before our average yeast runs completely out of stored carbs and starves to death.  Granted, they'd be darned weak after a week, but all we're needing is a few hours so I think the fact that metabolism is higher at room temp is insignificant as a practical matter.  I'm also not that certain there's a heck of a lot of protein synthesis going on in a mature, dormant yeast cell.  Its kind of the nature of dormancy, that a cell shuts down most synthesis activities and only keeps maintenance metabolism active.

Think we've made the OP sorry he asked the question yet?
Probably ;D

Enzyme activity is not important here, whether protein X is more active when 10C warmer doesn't matter.  Below 10C most yeast strains are shutting down and preparing to be frozen, I think you're right when you say that "I'm also not that certain there's a heck of a lot of protein synthesis going on in a mature, dormant yeast cell."  They will create cryoprotectants like trehalose and upregulate various proteins so that they can freeze solid and have a decent chance of survival.  They have evolved that way because if you don't start protecting yourself when it gets cold, then when it freezes you die.  So the things they are generating are different and they will eventually shut down as much as possible.  This is not the case at 20C, there they will be trying to grow and survive, using whatever carbon source they can find on hand, and in a beer ethanol is plentiful.

Obviously the yeast can survive much longer than a few weeks, I've cultured from bottles that are much older and shipped from Europe.  But I take what grows and baby it for a while and grow up a healthy population before I ask it to make me any beer.

I have yeast that is more than 4 years old, and it was more then 3 years old last time I checked it.  While he was working on the new book JZ asked me to update him on some stuff I did for NHC in Denver.  The yeast sitting at room temp (garage temp with large temperature fluctuations over the course of a year) were pretty messed up, but they were alive.  Every cell that grew formed a petite colony, indicative of a loss of mitochondrial function, which also means a loss of respiration ability.  The cells that I have at 4C and -20C came out much better - not as good as the -80C controls, but alive and functioning.  I didn't do any fermentation tests to see how they perform.

So anyway, I'm not convinced that warming them up will make a huge difference, but if temperature shock isn't an issue then there doesn't seem to be any upside to it . . . unless you are adding something to get it going, like happens in a wyeast smack pack, then that changes the equation. 
Tom Schmidlin