Yeast starter question

[sfish]

A beginner question, May not be worded right. Just looking for clarification.

Is the reason a starter is calculated to a certain volume amount because with that amount of sugars there is a set number of yeast cell that will grow and almost no alcohol will be produced?

Which is why you would step up a very large starter?

Than you in advance,
sfish

 

[mtnagel]

Yes that is correct, except you will get alcohol in a starter. You are basically making a small batch of beer. It will be <4% ABV or so, but you will get alcohol. And it probably won't taste very good.

 

[sfgoat]

The whole point of a starter is to allow the yeast to propagate under low stress conditions in order to acquire proper pitch rates. The volume (1L, 2L, etc) is to have an idea of amount of fermentable sugars available for cunsumption. You use a low gravity so as to not stress the yeast. Otherwise you could just do a high gravity one liter starter to acquire the rates as well but the yeast will be stressed and possibly cause off flavors.

 

[zeg]

Yes that is correct, except you will get alcohol in a starter. You are basically making a small batch of beer. It will be <4% ABV or so, but you will get alcohol. And it probably won't taste very good.

If you're careful (and hop your starter), you can get a perfectly drinkable small batch out of it. For big starters, this can be worth it if you hate throwing out beer.

 

[ACbrewer]

Yes that is correct, except you will get alcohol in a starter. You are basically making a small batch of beer. It will be <4% ABV or so, but you will get alcohol. And it probably won't taste very good.

This may or may not be true depending on your starter method.


Basically the yeast make alcohol as part of the breakdown of glucose. It then in the presence of Oxygen break the alcohol down further for more energy. If you don't oxygenate the starter well (ie just make and let sit, put an airlock on, etc) then you will have residual alcohol.
If however, you put a loose (usually aluminum foil) cover on, and especially if you agitate it-either by hand or with a stir plate, then you will force CO2 out, increase absorbtion of atmospheric O2 and if left long enough, get the yeast to convert all the sugar carbon dioxide and water.


Back to the OP's original question.
Through experimentation, they've found the amount of yeast cells that are growable in a given volume -gravity combo of wort. They've also determined what is a good pitch rate. Under and over pitching create off flavors.
to make life easier, starters are usually figured at about 1.040 gravity - the 1.035 to 1.040 range giving the best growth rate vs gravity. This means you only have to calibrate the volume to get the desired yeast count for a starting batch.
In the case of step up starters, going from a vial to a 1L to a 2L will get you more cells than going from a vial to 2L. Off hand, I'd guess this is because you start with more in the 1L and give it a fresh jolt of wort to work off of - and more sugar in total, where as from vial to 2L, the yeast cells have to fuel themselves on less sugar and such - dang not explaining that well. Sorry, not enough caffine.

I strongly recommend reading "YEAST" by White and Zainasheff for more on this and pitch rates.

 

[Warthaug]

Basically the yeast make alcohol as part of the breakdown of glucose. It then in the presence of Oxygen break the alcohol down further for more energy.
If you don't oxygenate the starter well (ie just make and let sit, put an airlock on, etc) then you will have residual alcohol.
If however, you put a loose (usually aluminum foil) cover on, and especially if you agitate it-either by hand or with a stir plate, then you will force CO2 out, increase absorbtion of atmospheric O2 and if left long enough, get the yeast to convert all the sugar carbon dioxide and water.

This isn't true. Yeast, in the presence of high concentrations of sugar (like you find in wort) engage in what is called the crabtree effect - a fancy name that simple means the yeast ferment sugar to alcohol despite the presence of oxygen. The only way you get yeast to fully metabolize sugar (e.g. turn sugar into CO2 and H2O), and get the resulting energy boost, is to carefully control sugar levels throughout the ferment, maintaining a sugar content equivalent to ~1.002 SG points. This is called batch-feed, and requires extremely expensive equipment (and reputably produces yeast with characteristics not amenable to making good beer).

What the addition of oxygen (via stirring) does is allow for the formation of unsaturated fatty acids and sterols, which are needed by yeast to then thrive in the low-oxygen environment of the ferment (these compounds stabilize yeast membranes). Stirring also reduces CO2 levels in the wort, which enables the fermentation of the sugars to go faster, accelerating the growth of the yeast in the starter. But the resulting "beer" is often unpleasant - high oxygenation also promotes ester formation, and while these are sometimes desired at low doses, they are pretty unpleasant at high concentrations.

As for the OP's question, the reason you step up a large starter is that you get more yeast from a stepped starter than you do from an equivalent volume single-step starter. As such you save $$$ in that you use less starter-wort and cheaper glassware. The yeast produced in multi-stage starters is also reputedly of higher quality, although I've not seen any proof that is true.

Bryan

 

[ACbrewer]

This isn't true. Yeast, in the presence of high concentrations of sugar (like you find in wort) engage in what is called the crabtree effect - a fancy name that simple means the yeast ferment sugar to alcohol despite the presence of oxygen. The only way you get yeast to fully metabolize sugar (e.g. turn sugar into CO2 and H2O), and get the resulting energy boost, is to carefully control sugar levels throughout the ferment, maintaining a sugar content equivalent to ~1.002 SG points. This is called batch-feed, and requires extremely expensive equipment (and reputably produces yeast with characteristics not amenable to making good beer).

If this were true - that is that yeast will not reuptake the alcohol and consume it in the presence of O2 - then our water supply would be drinkable as alcohol.

While the yeast may preferentially make alcohol over complete conversion, when the sugar is gone, it will take back up hte alcohol and consume it away IF there is oxygen. Early in the starter (or beer) the yeast use the O2 to make more yeast through (basically the sterols are needed for cell walls). But once a density of yeast cells is obtained, the yeast use the O2 for respiration, not reproduction, and they use up the alcohol while doing it.
Again, in YEAST this is described, and I think even has a nice diagram or 2 showing what the authors mean.

 

[Warthaug]

If this were true - that is that yeast will not reuptake the alcohol and consume it in the presence of O2 - then our water supply would be drinkable as alcohol.

Sorry, but you are completely wrong on this. The above comment doesn't even make sense - if 100% of the earth carbon were in the form of ethanol, you'd still only end up wit a fraction of a percent alcohol in our water (carbon is rare, compared to water, on earth). And you've mis-interpreted what was in Yeast as well...but what would I know - I'm only a microbiology prof with decades of experience working with yeast & other microorganisms :smack:

In nature yeast live in sugar-limited environments; skins of fruits, bark of trees, etc. Here they almost exclusively use the krebs cycle (oxidative respiration) in order to maximize the energy they extract from that limited supply of sugars. But while efficient, this process is slow. As such, when in a sugar-replete & oxidative environment, a lot of the sugar gets shunted through the glycolysis pathway, forming ethanol.

Ethanol itself is a very poor energy source for yeast as it produces both toxic by-products as well as excessive levels of NADPH; indeed, saccharomyces only effectively metabolizes ethanol in environments containing 1% or less ethanol. Above that the yeast growth decreases; above 4%, in the presence of oxygen, yeast simply become inert - just as if they were in an anoxic environment. Even in the low-ethanol ranges, catabolism of ethanol by yeast is limited; at 1% (optimal concentration for saccharomyces growth on ethanol) only about 1/4 of the ethanol is metabolized before the yeast enter dormancy. I'd also point out that achieving this sort of growth in-solution is nearly impossible; at room temperature the solubility of oxygen (from air) in water (~8mg/l) is on the lower-end of what is required for ethanol catabolism. Stir paltes typicallly don't get to that level; and instead provide 3-5mg/l O2. So without using pure O2, achieving that level of O2 is effectively impossible. In-lab, growth on ethanol is almost always done using plates.

In regards to starters, driving yeast through this metabolic pathway would be the last thing we would want to do - during this type of growth yeast upregulate a broad swath of genes specific to this form of metabolism, while turning off many of the genes required for proper beer fermentation.

Bryan

 

[aslander]

Haha, I love HBT. A beginner's question turns into a scientific debate! Regardless, interesting info either way

Sent from my SCH-I545 using Home Brew mobile app

 

[sfish]

Haha, I love HBT. A beginner's question turns into a scientific debate! Regardless, interesting info either way

I thank you all. I feel my joining the forum is well wourth this education.

 

[sfish]

Well,, If I harvested yeast from 2 bottles of brew into a one pint starter. 1/2 cup DME per quart. Then picthed into a quart starter. Can I figure how much yeast there is?

 

[ACbrewer]

Well,, If I harvested yeast from 2 bottles of brew into a one pint starter. 1/2 cup DME per quart. Then picthed into a quart starter. Can I figure how much yeast there is?

not unless you know how much yeast you started with. I was going to send you to mr.malty where you can play with that sort of stuff, but without a start count, I don't think you can figure it out.

Let me put it this way. IF you get 300% increase in cells, but don't know how much you stated with, you only know you got 3x what you started with - see the problem? I've seen estimates on how much can be recovered from the bottle of beer, and with equipment (microscope and other tools) you can count how many cells you have and figure it that way, But with out a known start point, you just know you have growth.


Remember to decant and toss the liquid and only pitch the solid into your next batch of beer.

Beer= keep liquid throw solid.
Starters= keep solids through most of the liquid.

 

[Warthaug]

sfish,

As AC said its not possible to determine exactly how many yeast you have. What I would recommend is:

1) If storing the yeast, take a sample now and store however you normally do so
2) Build the starter upto ~ 1.5L (1.5qt)
3) Pitch into a modest-gravity beer - 1.050 or lower.

Regardless of your exact counts, you should have more than enough yeast with this process to ferment a beer of this strength. You could then wash and use the slurry/top-crop from this first batch in later batches of beer. There are good guidelines out there about how to determine the approximate number of yeast in washed or top-cropped yeast samples, so once this first batch is done you should have a better handle on yeast numbers.

Hope that helps.

Bryan

 

[mtnagel]

Well,, If I harvested yeast from 2 bottles of brew into a one pint starter. 1/2 cup DME per quart. Then picthed into a quart starter. Can I figure how much yeast there is?

I've heard you should assume 1 - 2 billion cells per bottle.

Using brewersfriend.com, after the first step, you'd have about 11 billion cells and after the second step, you'd have about 56 billion cells. Just estimates of course, but that should get you started.

 

[sfish]

I've heard you should assume 1 - 2 billion cells per bottle.

Using brewersfriend.com, after the first step, you'd have about 11 billion cells and after the second step, you'd have about 56 billion cells. Just estimates of course, but that should get you started.

Thank you, lesson learned.

I am making beer tonight and it looks like I will be severly underpitching. See what happens.

sfish

 

[mtnagel]

Well I just reread and saw you are using 2 bottles, so that's double what I said.

I like yeastcalc.com better, but it was down when I ran those numbers before. Using yeast calc and assuming 3 billion cells to start, and assuming you used a stir plate, you'd either have 102 billion cells using Jamil's calculations (this is where brewersfriend must get their equations from because it's close to what I said before except doubled). If you use Kai's numbers, you get 200 billion cells. So I'd assume somewhere in the middle

You can also get an estimate based on the amount of yeast slurry you have if you have the volume. MrMalty says they will range from 1-4.5 billions/ml from a thin slurry to a thick slurry. If it's been in the fridge and nice and compact, I'd go towards the high end of that range. Take the ml of slurry you have and multiply it by the concentration above to get the amount you have.

 

[timcadieux]

Tim Horton's coffee....its 10:30 am..sorry

 

[johnnv]

I looked at mrmalty calculator yesterday, never have seen it before. Another poster on here said that he uses that. It can't work in my opinion, at best you can use that calculator, pitch the described amount of yeast in a stater and wake it up for a few hours. What a waste of money. Mrmalty says for a 10 gallon batch, you need 2 vials of yeast and 2.5 liter starter. Problem with that is you could have 100 billion cells in 2.5 liters or 500 billion cells. There are to many variables.

The only way you can really know your cell rate per ml is with a hemocytometer and a microscope and actually count them.

Without doing that, my method is this, very simple. I store approximately 100 - 150 billion cells in refrigeration. About 3 or 4 days before I am ready to brew. I make a 2000ml starter around 1.040 gravity with about 1/4 tsp yeast nutrient, at 75 -80 degrees F, well oxegenated and a stir plate. Pitch the yeast, few hours later a little more nutrient, by 36 - 48 hours the starter will be fermented out. You can double check this with a hydrometer. Adding more DME or sugar will wake it all up. Still on stir plate, by the 3rd or 4th day you should have 400 billion cells or more. I pitch half or more and store the rest for future use.
Without getting wrapped up in scientific methods and lab procedures, this is a sound way to approach this subject.

 

[mtnagel]

Of course you can do that. And you'll probably make some good beer most of the time. But I'm way too anal to do it that way. Are you saying that you are doing that for every beer from a mild ale to an imperial stout? Those require much different amount of yeast that your method doesn't take into account.

I like that I can enter in a number into a spreadsheet or online calculator and get a number out. It makes me feel good. Even though these are approximations on approximations without using a hemocytometer as you mention.

I do have a problem where you say it, "can't work." What do you mean by that? Lots and lots of people use Jamil's and other online calculators. Are they all making bad beer or wasting money? The calculators are based on data through experimentation. As I said, they are an approximation, but they are better than just picking some arbitrary starter amount to use for every single beer you make.

Also, just because Jamil's calculator says you need 2 packs, doesn't mean you can't do a bigger starter or a multi-step starter to get to your necessary yeast amount. I like yeastcalc.com because it's easier to do multi-step starters.

 

[sawbossFogg]

I just read through this thread, as I've been searching for a few answers myself. First, I use the brewers friend calc, namely over the others cause it gives predictions of cell counts for the dry yeasts I like based on the grams pitched and production date based viability. Of course there are variables and thats why were all trying to get to a reasonably appropriate end state of an applicable pitch rate.

If anyone's still paying attention to this thread, I'm working toward two questions that will also lend greatly to the original thread.

1) The number one variable that all the yeast calculators avoid is TIME. This has been a challenge I've been trying to figure out over a year of making starters. It seems that with a given number of cells and a OG and a FG an end number is predictable, my problem is how are folks getting accurate FG readings. As far as I understand my refractometer isn't going to give an accurate reading with OH in the mix and I don't really want to dump a bunch of the wort into a cylinder with yeast in solution, so how do folks do this?
Also how long do folks really cold crash for when making big, multi step say 4L starters? I can't be putting all that crappy wort in my beer?

Thanks!!

 

[mtnagel]

I always let my starters go 2 days and I always let my starters crash in the fridge for 2 days. I don't test the final gravity of the starter, but I bet it's done. Might be overkill, but if I plan far enough ahead, it's no big deal.

 

[sawbossFogg]

I always let my starters go 2 days and I always let my starters crash in the fridge for 2 days. I don't test the final gravity of the starter, but I bet it's done. Might be overkill, but if I plan far enough ahead, it's no big deal.

Thanks! After the cold crash and the decant, I'd imagine that warming to room temp and rinsing the yeast cake out of the flask with the wort to be pitched is a good method?

 

[helibrewer]

Thanks! After the cold crash and the decant, I'd imagine that warming to room temp and rinsing the yeast cake out of the flask with the wort to be pitched is a good method?

I just leave a couple hundred ml's when I decant and use that to swirl loose the yeast cake....don't forget your stir bar before you dump it into the fermenter

 

[Adam_Selene]

A beginner question, May not be worded right. Just looking for clarification.

Is the reason a starter is calculated to a certain volume amount because with that amount of sugars there is a set number of yeast cell that will grow and almost no alcohol will be produced?

Which is why you would step up a very large starter?

Than you in advance,
sfish

The ultimate purpose of a starter is to grow a relatively weak population of yeast up to a relatively strong population of yeast. Don't worry about it.

As a beginner, don't bother about pitching rates, and starters.
Get some dry yeast and pitch it directly. If you get liquid, and it's less than a month old, pitch that directly.

Also. If your just doing five gallons in your kitchen, or even ten. You DON'T need an erlenmeyer flask and a stir plate. Your not a brewery. Your not trying to respirate the population up many orders of magnitude so you can dump that into a giant tank of wort. We are on the measuring cup/bucket scale here. Relax.

--Adam Salene

 

[mtnagel]

Thanks! After the cold crash and the decant, I'd imagine that warming to room temp and rinsing the yeast cake out of the flask with the wort to be pitched is a good method?

Do as helibrewer says, but if you don't leave enough liquid behind, you can do as you said and transfer a small amount of your new wort to help transfer all the yeast slurry over.

I just leave a couple hundred ml's when I decant and use that to swirl loose the yeast cake....don't forget your stir bar before you dump it into the fermenter

LOL yes, good tip on the stir bar!

The ultimate purpose of a starter is to grow a relatively weak population of yeast up to a relatively strong population of yeast. Don't worry about it.

As a beginner, don't bother about pitching rates, and starters.
Get some dry yeast and pitch it directly. If you get liquid, and it's less than a month old, pitch that directly.

Also. If your just doing five gallons in your kitchen, or even ten. You DON'T need an erlenmeyer flask and a stir plate. Your not a brewery. Your not trying to respirate the population up many orders of magnitude so you can dump that into a giant tank of wort. We are on the measuring cup/bucket scale here. Relax.

--Adam Salene

There is something to be said for the KISS method, but there's also nothing wrong with trying to doing things correctly, even as a beginning. Underpitching is bad, so why not try to do it correctly?

 

[sawbossFogg]

The ultimate purpose of a starter is to grow a relatively weak population of yeast up to a relatively strong population of yeast. Don't worry about it.

As a beginner, don't bother about pitching rates, and starters.
Get some dry yeast and pitch it directly. If you get liquid, and it's less than a month old, pitch that directly.

Also. If your just doing five gallons in your kitchen, or even ten. You DON'T need an erlenmeyer flask and a stir plate. Your not a brewery. Your not trying to respirate the population up many orders of magnitude so you can dump that into a giant tank of wort. We are on the measuring cup/bucket scale here. Relax.

--Adam Salene

This is poorly played. Yes we've all successfully pitched dry yeast and smack packs into 5 gallon fermentors, but big 5's need at least double packs (which may be cost effective), However, big 10 gallon batches will be stressed and yucky without a good starter. Underpitching wort is the worst thing you can do after you've put much time, energy and $ into a mash and everything else. The calculators are simple and very appropriate. Thats my opinion from 20 years as a lowly home brewer.

 

[zeg]

Without doing that, my method is this, very simple. I store approximately 100 - 150 billion cells in refrigeration. About 3 or 4 days before I am ready to brew. I make a 2000ml starter around 1.040 gravity with about 1/4 tsp yeast nutrient, at 75 -80 degrees F, well oxegenated and a stir plate. Pitch the yeast, few hours later a little more nutrient, by 36 - 48 hours the starter will be fermented out. You can double check this with a hydrometer. Adding more DME or sugar will wake it all up. Still on stir plate, by the 3rd or 4th day you should have 400 billion cells or more. I pitch half or more and store the rest for future use.
Without getting wrapped up in scientific methods and lab procedures, this is a sound way to approach this subject.

You do realize that your method is essentially identical to running one set of numbers on MrMalty, then using that solution for every beer, right?

This is poorly played. Yes we've all successfully pitched dry yeast and smack packs into 5 gallon fermentors, but big 5's need at least double packs (which may be cost effective), However, big 10 gallon batches will be stressed and yucky without a good starter. Underpitching wort is the worst thing you can do after you've put much time, energy and $ into a mash and everything else. The calculators are simple and very appropriate. Thats my opinion from 20 years as a lowly home brewer.

I think pitching an appropriate amount of dry yeast is probably the best approach for inexperienced brewers. I've only ever used 11g packs, so I think in terms of those, but they are aimed at 5 gallon batches and are sufficient for up to OGs of 1.07 or 1.08. If you're doing larger batches, you don't need to get too clever---just increase the number of packs proportionally.

If the calculator is intimidating, I think this is a more than adequate method that is unlikely to steer you very wrong.

 

[Adam_Selene]

Do as helibrewer says, but if you don't leave enough liquid behind, you can do as you said and transfer a small amount of your new wort to help transfer all the yeast slurry over.

LOL yes, good tip on the stir bar!

There is something to be said for the KISS method, but there's also nothing wrong with trying to doing things correctly, even as a beginning. Underpitching is bad, so why not try to do it correctly?

What incorrectness are you talking about? Your average beginner is going to have a hard time under pitching, unless they stress themselves out because they read too much-- over think things and kill half the population by loving it to death before it gets a chance to touch the wort.

If your talking about using an erlenmeyer flask and a stir-plate to start 5 or 10 gallons, that's not incorrect. It's just silly, and a complete waste of time for some one that is just starting out.

--Adam Selene

 

[Adam_Selene]

This is poorly played. Yes we've all successfully pitched dry yeast and smack packs into 5 gallon fermentors, but big 5's need at least double packs (which may be cost effective), However, big 10 gallon batches will be stressed and yucky without a good starter. Underpitching wort is the worst thing you can do--

No, it's not. If I had to choose I would rather have a slow climb in population in an extremely well sanitized primary than a rapid climb in questionably sanitized primary. Low or high temperature.

And, I didn't say anything about under pitching.

after you've put much time, energy and $ into a mash and everything else. The calculators are simple and very appropriate. That's my opinion from 20 years as a lowly home brewer.

I think what your telling me here is that the amount of yeast really maters to you. I don't disagree with that. It maters to me too. I also drink my own beer. What I disagree with, and dislike is the overemphasis on the preparation of yeast that beginners are picking up. This is a world where sometimes you need TWO packages instead of one. (look at the date on the package at least)

There is enough for a beginner to deal with already without having to become an amateur microbiologist.

--Adam Selene

 

[mtnagel]

What incorrectness are you talking about?

I was talking about this statement:

If you get liquid, and it's less than a month old, pitch that directly.

If you used a 1 month old pack of liquid yeast, you'd have roughly 75 billion cells and you should only pitch that into a 5 gallon, 1.021 wort or lower or you are underpitching. 10 gallons is even worse.

If you don't believe in the pitching rate that experts advocate (0.75 - 1 million cells of viable yeast, for every milliliter of wort, for every degree plato) then there is nothing really else to say.

I'm also saying this may be incorrect:

Get some dry yeast and pitch it directly.

If you properly rehydrate dry yeast, for a 1 month old 11.5 g packet, you can make a 5 gallon, ~1.056 beer or you are underpitching.

Again, if you don't agree with the established pitching rate, then there is nothing else to say.

No, it's not. If I had to choose I would rather have a slow climb in population in an extremely well sanitized primary than a rapid climb in questionably sanitized primary. Low or high temperature.

And, I didn't say anything about under pitching.

You are advocating underpitching - see my math above.

There is enough for a beginner to deal with already without having to become an amateur microbiologist.

But I feel it's better to educate beginner brewers and then they can decide how much effort they want to put into their beer.

In the beginning, I too just sprinkled the dry yeast on my beer and I thought it was pretty good - it really wasn't. It was okay and drinkable, but after using appropriate pitching rates, controlling fermentation temperatures and figuring out water chemistry, my beers have gotten a lot better.