Yeast starter has media sediments at the bottom: how to dissolve it back?

[AnbyG]

Hi everybody,

So last Sunday I tried my hands in preparing/propagating a yeast starter, primarily to avoid having to shell out out ~ $8 bucks for liquid yeast packs. In December I had purchased a packet of WLP 400, which was accidentally left in room temperature for 4-5 days and best use expiry date in late Feb. The idea was to pitch this entire (almost) packet of yeast in the 5.5 gallon batch of Belgian wheat beer. And a couple of drops from the WLP 400 packet was to go in yeast starter media in bottles to grow yeast for another batch.

So I boiled ~125 g dry pilsner malt extract in approximately 1L water (final volume), put it in two sanitized plastic bottles (did not have time to buy & ship magnetic stir plate & Eylenmeyer flask on time), cooled them down to room temp, pitched the yeast in one bottle and capped them up. Right after I pitched the yeast I noticed sediments at the bottom of the bottles, which must have precipitated after the cool down. A few days after pitching, I tried to swirl/shake the bottles to dissolve it back as some of the nutrients have been eaten by the yeast, but it did not work.

The left bottle is the one with yeast in it, and the one on the right is the spare bottle. In hindsight, I should have bought smaller foam plugs as it is probably restricting gas exchange. What can I do to dissolve it back and to separate the yeast from the precipitated media?

Thanks
AnbyG

 

[day_trippr]

Interesting - first thought was "if the dme was boiled where'd all that precipitate come from?
But then again, I always put my starters on a stir plate, so if there was precipitation it'd never be evident, so I'd be inclined to ignore it.

In that regard, wrt the inoculation rate, "a few drops" from an old yeast package into ~1.044 wort is going to take a long time to show any change. With that small a starting cell count I'd have gone with 100 ml of 1.020-ish wort for that first stage and work up from there...

Cheers!

 

[RPh_Guy]

The sediment is break material and it's completely normal, not a problem.

Instead of the stopper, you can cover it loosely with foil.

100 g/L DME is sufficient.

 

[AnbyG]

Interesting - first thought was "if the dme was boiled where'd all that precipitate come from?
But then again, I always put my starters on a stir plate, so if there was precipitation it'd never be evident, so I'd be inclined to ignore it.

In that regard, wrt the inoculation rate, "a few drops" from an old yeast package into ~1.044 wort is going to take a long time to show any change. With that small a starting cell count I'd have gone with 100 ml of 1.020-ish wort for that first stage and work up from there...

Cheers!

It looks like fermentation in that bottle has come to a stop, there are no bubbles rising from the bottom any more. Yes, I understand that with inoculum it would take some time. It has been 6 days already.

Do you use a heated stir plate to keep the temperature at optimal 37 degrees celsius? I am considering getting one as it would grow much faster at 37 than at room temperature.

The sediment is break material and it's completely normal, not a problem.

Instead of the stopper, you can cover it loosely with foil.

100 g/L DME is sufficient.

Thanks, good to know it is normal. I had never observed it in any of my wort that I had prepared before, probably because it is not so concentrated. What exactly is break material? Proteins with low solubility that precipitated out due to high concentration? I wonder if lowering the concentration to ~40g/L and doubling the volume would get me a larger quantity of yeast per unit gram DME basis. In labs when we grew yeast on LB media (and 37 degree celsius) the concentration was ~25 g/L.

 

[RPh_Guy]

What exactly is break material?

Two things:

1. Hot break, which is coagulated proteins. They coagulate because of the heat/denaturization. That's why it's called hot break; it forms toward the beginning of the boil.
2. Cold break, which is precipitated lipids and fatty acids, forms as it cools, due to solubility.

I wonder if lowering the concentration to ~40g/L and doubling the volume would get me a larger quantity of yeast per unit gram DME basis.

Pretty sure research has shown that 1.030-1.040 wort gives the best growth, but I don't have any studies handy.

 

[Jayjay1976]

6 days is still reasonable lag time considering you pitched such a small inoculation. It might kick up tomorrow morning and be done by the following afternoon. RDWHAHB

 

[day_trippr]

fwiw, recommendations for reviving yeast dregs from bottled commercial beers often suggest doing a 100ml starter of 10 point wort for the initial growth attempt. I presume there's some perceived intrinsic frailty to bottle dregs that's being accommodated, and consider "a couple drops" from an actual yeast package to be in the same neighborhood. Hence the "soft start" to growing the culture...

Cheers!

 

[isomerization]

It looks like fermentation in that bottle has come to a stop, there are no bubbles rising from the bottom any more. Yes, I understand that with inoculum it would take some time. It has been 6 days already.

Do you use a heated stir plate to keep the temperature at optimal 37 degrees celsius? I am considering getting one as it would grow much faster at 37 than at room temperature.



Thanks, good to know it is normal. I had never observed it in any of my wort that I had prepared before, probably because it is not so concentrated. What exactly is break material? Proteins with low solubility that precipitated out due to high concentration? I wonder if lowering the concentration to ~40g/L and doubling the volume would get me a larger quantity of yeast per unit gram DME basis. In labs when we grew yeast on LB media (and 37 degree celsius) the concentration was ~25 g/L.

37 C is pretty high (30 C is more typical) and LB media is commonly used for E. coli cultures, are you sure you aren’t confused?

Regardless, I use a heat wrap to keep my yeast starters at 30C. My basement is normally 15-16C, so I find this helps quite a bit.

 

[AnbyG]

Two things:

1. Hot break, which is coagulated proteins. They coagulate because of the heat/denaturization. That's why it's called hot break; it forms toward the beginning of the boil.
2. Cold break, which is precipitated lipids and fatty acids, forms as it cools, due to solubility.

Pretty sure research has shown that 1.030-1.040 wort gives the best growth, but I don't have any studies handy.

Got it, that makes sense. The other day I boiled 105g of same DME in 1.1 liter of water for about 15 minutes. No precipitation at all this time though. Wonder why.

6 days is still reasonable lag time considering you pitched such a small inoculation. It might kick up tomorrow morning and be done by the following afternoon. RDWHAHB

fwiw, recommendations for reviving yeast dregs from bottled commercial beers often suggest doing a 100ml starter of 10 point wort for the initial growth attempt. I presume there's some perceived intrinsic frailty to bottle dregs that's being accommodated, and consider "a couple drops" from an actual yeast package to be in the same neighborhood. Hence the "soft start" to growing the culture...

Cheers!

I inoculated another 1 L bottle (fresh boiled DME, no precipitate this time) with yeast cultured from the bottle with sediments. The growth this time was much better.

37 C is pretty high (30 C is more typical) and LB media is commonly used for E. coli cultures, are you sure you aren’t confused?

Regardless, I use a heat wrap to keep my yeast starters at 30C. My basement is normally 15-16C, so I find this helps quite a bit.

Oops, my bad. Yes, 37C was for E. coli. IF I recall correctly we set it at 32C for yeast.

 

[IslandLizard]

BrewUnited's Yeast Calculator

Keep an eye on the inoculation rate info cell.

You really need to introduce oxygen (air) into the starter beer while the yeast is propagating for maximum culture growth. Just letting it sit in a narrow mouth bottle is not enough.

Also looks up "shaken-not-stirred" starters. It's a good alternative to stir plates. It takes a little work and attention, though. A gallon jug works well to make 5 gallon pitchable size slurries. For smaller cultures, a quart jug or liter bottle will work better.