Yeast Starter - Gauge Progress

[jmelbye]

I've read some posts that suggest your yeast starter is ready at high krausen. I've also read others that say you don't want the yeast to form a krausen and should use something like a stir plate for better results.

My question is if the starter is sitting on a stir plate, are there any visual cues I can look for to gauge how it is doing and when it has reached its peak readiness (since it will not be forming a krausen)?

I have a stir plate that I used to prepare a starter for my last beer. The starter had a good amount of bubbles at the top, but I think that is more a result of the stirring than the yeast production. My last starter turned out fine - my beer hit it's target final gravity and tastes good. But it was mostly guess work.

A follow up question is what is the purpose of cold crashing the starter? Is it solely so the yeast will settle out allowing you to pour off the excess liquid? Or is there more to it than that?

Thanks!

 

[Schnitzengiggle]

I've read some posts that suggest your yeast starter is ready at high krausen. I've also read others that say you don't want the yeast to form a krausen and should use something like a stir plate for better results.

The yeast may krausen even when using a stir plate, when I bump my starters up from 2 to 3-4 liters I normally get a good blow off even though the starter is on a stirplate.

My question is if the starter is sitting on a stir plate, are there any visual cues I can look for to gauge how it is doing and when it has reached its peak readiness (since it will not be forming a krausen)?

Tiny bubbles...the stir plate is used to promote co2/o2 gas exchange, however the yeast is still going to produce co2 during the growth phase. Yeast don't all go through the same phase of growth at the same time, so while a starter is mainly to promote the aerobic growth phase you will have some yeast in an anaerobic state fermenting and producing co2, at some point nearly all of the yeast will be in an anaerobic state as the wort sugars in the starter are depleted. Other than looking for tiny bubbles, take the foil cap off and take a sniff, if the starter smells bready and yeasty, then there is a good chance you have a viable starter. (Next time you make a starter smell the wort before you pitch your yeast, then smell the wort a few hours later or the next day, there should be a noticeable difference in odor.)

I have a stir plate that I used to prepare a starter for my last beer. The starter had a good amount of bubbles at the top, but I think that is more a result of the stirring than the yeast production. My last starter turned out fine - my beer hit it's target final gravity and tastes good. But it was mostly guess work.

Tiny Bubbles are a good sign.

A follow up question is what is the purpose of cold crashing the starter? Is it solely so the yeast will settle out allowing you to pour off the excess liquid? Or is there more to it than that?

There are differing opinions on cold crashing and pitching at high krausen. Pitching at high krausen allows the yeast to get straight to work, they are in their most active state and will start fermentation quickly.

Cold crashing settles out nearly all the yeast with the exception of some of the least flocculent cells. On the other hand, cold crashing allows yeast to go dormant and rebuild their glycogen reserves which is a plus for cell health.

I have pitched both at high kausen, and cold crashed and decanted. Basically, if I am using a large starter for a higher OG beer, then I will chill and decant as I don't want to add a gallon of starter wort to my 5 gallons of beer (1:5 is a decent ratio of starter to wort) which may lead to some off flavors that might have been produced within the starter.

If I am using a 1-2 liter starter in a normal gravity beer and I don't have time to chill and decant, then I will pitch the entire starter into the wort.

Either method produces great results in my experience. However, I will say that starters pitched at high krausen in my brewery usually start between 2-5 hours, where chilled and decanted starters will take a few hours longer (5-10).

Cheers!

 

[DUNDASJ]

I can only answer the question about putting it in the refrigerator and letting the yeast settle. I currently got my first starter going and read that some people do it to dump the excess liquid while others take theirs right off the stir plate and dump it in.

Another reason for doing it that way is to do a step up starter which is what I'm doing. My recipe calls for 400 billion cells or more simply put about 4 smack packs. The step up starter is a way to make more yeast out of a small amount.

I'm doing this 1L starter with 100g of DME put on stir plate for 2 days then refrigerate overnight, let yeast settle and dump excess liquid then add another 1 liter starter and let it sit for another 2 days cool decanter liquid and pitch into 10 gallons of coconut porter.

 

[Schnitzengiggle]

I can only answer the question about putting it in the refrigerator and letting the yeast settle. I currently got my first starter going and read that some people do it to dump the excess liquid while others take theirs right off the stir plate and dump it in.

Another reason for doing it that way is to do a step up starter which is what I'm doing. My recipe calls for 400 billion cells or more simply put about 4 smack packs. The step up starter is a way to make more yeast out of a small amount.

I'm doing this 1L starter with 100g of DME put on stir plate for 2 days then refrigerate overnight, let yeast settle and dump excess liquid then add another 1 liter starter and let it sit for another 2 days cool decanter liquid and pitch into 10 gallons of coconut porter.

Just make sure you use a large enough container because at some point the yeast will not have the ability to multiply further after all of the available space is used up.

In other words, regardless of the amount of sugar left for the yeast to munch on, there is still a limit to how many cells can occupy a certain volume-- the idea is similar to carrying capacity.

As an example it is extremely unlikely that you will be able to propagate 400 billion cells in a 1 liter flask no matter how many times you chill decant and add fresh wort there simply isn't enough space for the yeast to multiply to that extent in such a small volume.

 

[DUNDASJ]

Just make sure you use a large enough container because at some point the yeast will not have the ability to multiply further after all of the available space is used up.

In other words, regardless of the amount of sugar left for the yeast to munch on, there is still a limit to how many cells can occupy a certain volume-- the idea is similar to carrying capacity.

As an example it is extremely unlikely that you will be able to propagate 400 billion cells in a 1 liter flask no matter how many times you chill decant and add fresh wort there simply isn't enough space for the yeast to multiply to that extent in such a small volume.

Keep in mind this is my first starter but I am also using a 2 L flask so I "think" I should be ok. I was thinking about just doing a 2 step starter and from the yeast calc it said that would put me at about 360 billion and then I was just going to throw in an activated smack into the fermentor to make up for the rest because I don't have the time or really feel like doing a 3 step starter.

If you guys didn't already know Bell's brewing Company sells homebrew stuff online. Got my 2 L flask for only 16.50!

 

[TrubHead]

The yeast may krausen even when using a stir plate, when I bump my starters up from 2 to 3-4 liters I normally get a good blow off even though the starter is on a stirplate.



Tiny bubbles...the stir plate is used to promote co2/o2 gas exchange, however the yeast is still going to produce co2 during the growth phase. Yeast don't all go through the same phase of growth at the same time, so while a starter is mainly to promote the aerobic growth phase you will have some yeast in an anaerobic state fermenting and producing co2, at some point nearly all of the yeast will be in an anaerobic state as the wort sugars in the starter are depleted. Other than looking for tiny bubbles, take the foil cap off and take a sniff, if the starter smells bready and yeasty, then there is a good chance you have a viable starter. (Next time you make a starter smell the wort before you pitch your yeast, then smell the wort a few hours later or the next day, there should be a noticeable difference in odor.)



Tiny Bubbles are a good sign.



There are differing opinions on cold crashing and pitching at high krausen. Pitching at high krausen allows the yeast to get straight to work, they are in their most active state and will start fermentation quickly.

Cold crashing settles out nearly all the yeast with the exception of some of the least flocculent cells. On the other hand, cold crashing allows yeast to go dormant and rebuild their glycogen reserves which is a plus for cell health.

I have pitched both at high kausen, and cold crashed and decanted. Basically, if I am using a large starter for a higher OG beer, then I will chill and decant as I don't want to add a gallon of starter wort to my 5 gallons of beer (1:5 is a decent ratio of starter to wort) which may lead to some off flavors that might have been produced within the starter.

If I am using a 1-2 liter starter in a normal gravity beer and I don't have time to chill and decant, then I will pitch the entire starter into the wort.

Either method produces great results in my experience. However, I will say that starters pitched at high krausen in my brewery usually start between 2-5 hours, where chilled and decanted starters will take a few hours longer (5-10).

Cheers!

Thanks for this information since "gauging yeast progress" has varied for this new brewer.