2L starter question - vessel size

[schach23]

Guys,

Planned on doing the more beer Pliny all grain kit and have a Wyeast 1056.

First time making a starter

OG 1.070

Wyeast says I need a 2L starter. I plan on using a stir plate. I have a 2 L Pyrex flask I was going to use. Is my vessel size big enough? Is there enough head space? I don't want to wake up to my starter krausen all over my counter and stir plate.

Thanks

Scott

 

[PoppinCaps]

Add some FermCap and you'll be fine. Without it, you'll probably have a little mess. I would just save the DME and go 1.5L on a stir plate, that will be plenty of cells for 1.070 with some head space.

 

[jekeane]

Use a yeast calculator with your viability date to be sure. Mr Malty says you would be fine with a 1.5L starter if your yeast is 4 months old.

 

[WoodlandBrew]

You could also use 200g of DME in 1.5L of water. Biomass yield is dependent on the amount of sugar (and is independence of gravity pitch rate for the most part) so the final yield will be nearly the same. Growth rate in a batch culture is going to mostly unrestricted in a batch culture (limited by maximum flux rates of the cell) so no worries there either.

 

[schach23]

Did my starter and now it's done. I won't be brewing for another 24 hrs. What should I do with the starter? Keep it on the stir plate on low? Or just keep covered with foil at room temp until I pitch? Thanks

 

[El_Condor]

Personally, I'd stick it in the fridge. That will allow the yeast slurry to settle out of suspension and also work on its energy stores. You can take it out of the fridge a few hours before pitching to let it get to room temp, and should be able to decant some of that clear, useless starter beer off the top.

 

[schach23]

Thanks

 

[WoodlandBrew]

Glycogen and other carbohydrate reserves are built at the end of fermentation (When the sugar that can be metabolized is nearly depleted) Once the starter is complete it should be stored in the fridge to slow the yeast. If it is left at room temperature the yeast will metabolize the glycogen energy reserves that you allowed it to create. Lack of these reserves will lead to a slow start of fermentation.

 

[frankktankk]

Usually I start with 1l + 100g DME and after 24-36h I add 0.5l and 150g DME (boiled 15mins or sterilized) for a 2l E-flask.

 

[Smellyglove]

Glycogen and other carbohydrate reserves are built at the end of fermentation (When the sugar that can be metabolized is nearly depleted) Once the starter is complete it should be stored in the fridge to slow the yeast. If it is left at room temperature the yeast will metabolize the glycogen energy reserves that you allowed it to create. Lack of these reserves will lead to a slow start of fermentation.

Why does it metabolize it's own reserves? There's nothing left in the starter to eat, so what does it use the glycogen for after fermentation?

 

[WoodlandBrew]

Why does it metabolize it's own reserves? There's nothing left in the starter to eat, so what does it use the glycogen for after fermentation?

If the temperature is warm enough the yeast will stay active. If there is no carbon source in solution yeast will burn the glycogen. It's similar to fat in mammals. If there is no food, mammals metabolize their stored fat for energy.

 

[schach23]

Thanks guys for the discussion

Put it in the fridge overnight to slow things down - metabolism wise. It was surely done fermenting. Brought it out this morning to get it to room temp for brew day. Not gonna worry about decanting.

Morebeer Pliny clone all grain today!

First all grain batch

Yeast after starter finished on new stir setup


New equipment and mini sculpture



Scott

 

[Smellyglove]

If the temperature is warm enough the yeast will stay active. If there is no carbon source in solution yeast will burn the glycogen. It's similar to fat in mammals. If there is no food, mammals metabolize their stored fat for energy.

Alright! Thanks!

So, another Q. People pitching starters at high krausen, do they pithc yeast which has a shorter "burn time" since the glycol reserves is already used up?

 

[WoodlandBrew]

Alright! Thanks!

So, another Q. People pitching starters at high krausen, do they pithc yeast which has a shorter "burn time" since the glycol reserves is already used up?

When pitching at high krausen the yeast is already active and the membrane is already placid so there is no need for stored glycogen. Glycogen is useful when the yeast is transitioning from the stationary phase to the growth phase. When yeast is dormant in the stationary phase the cell membrane is more rigid, and nutrients cannot pass effectively though it. Having an internal supply of energy in the form of glycogen the yeast can synthesize the sterols needed for proper membrane fluidity without relying one external nutrient. Having a sufficient glycogen reserve makes lag time shorter.

What you don't want to do is take a culture that is at high krausen and then move it to the fridge. There is very little stored glycogen at this phase and the cold temperature will put the yeast into dormancy. When the yeast are revived the membrane will not be ready to absorb nutrients, and there will be little glycogen from which to prepare the membrane. Eventually the yeast will get going, but the lag time could be twice as long as normal.

 

[Smellyglove]

When pitching at high krausen the yeast is already active and the membrane is already placid so there is no need for stored glycogen. Glycogen is useful when the yeast is transitioning from the stationary phase to the growth phase. When yeast is dormant in the stationary phase the cell membrane is more rigid, and nutrients cannot pass effectively though it. Having an internal supply of energy in the form of glycogen the yeast can synthesize the sterols needed for proper membrane fluidity without relying one external nutrient. Having a sufficient glycogen reserve makes lag time shorter.

What you don't want to do is take a culture that is at high krausen and then move it to the fridge. There is very little stored glycogen at this phase and the cold temperature will put the yeast into dormancy. When the yeast are revived the membrane will not be ready to absorb nutrients, and there will be little glycogen from which to prepare the membrane. Eventually the yeast will get going, but the lag time could be twice as long as normal.

Aight. Thanks again! this post calls for a bookmark.