yeast x 6

[PD]

At the moment I use dried yeasts and I'm a sprinkler. My two main yeasts are Sa-04 for meaty malty beers and S05 for IPA types.
However my last brew I used a liquid yeast and was very impressed with how it fermented. I also used that yeast cake for a second similar type beer and was equally impressed.
Now being a yorkshire man, sprinkly yeasts cost me around £3 a throw and the liquid one cost me £6.
There was a recent post refering to an older forum thread thats got me started on a new project.

viewtopic.php?f=30&t=155

So Ive decided to make a small yeast bank of yeasts that I use, ensuring that I've plenty of yeasts in stock and at a much reduced cost.
I've no liquid yeast available at the moment so I've multiplied the humble S04 as a trial.

I followed the process as outlined above and sprinkled a packet of 04 onto 2 liters of boiled cooled DME ( 100 gms per litre )
The demi john is presently sitting in the kitchen bubbling furiously, it will be left to work out completely and settle out.
I then intend to split the increased yeast between 6 pet bottles and place them into my cold fridge.

On my next order I think I'll be getting a couple of liquid yeasts and repeating the process.

Now 6 pet bottles per yeast type begin to take up quite a bit of room in fridges whats the better way of storing.
I thought about collecting 6 teaspoons of the yeast into urine sample bottles and freezing would this be better ?

Its all good fun tho....

 

[graysalchemy]

I would freeze them.

50% washed yeast, 25% glycerine. 25% boiled cooled water. Put into sterilised sample tubes. :thumb:

 

[pittsy]

forget it a 2nd fridge is needed , however you do it you'll have half a fridge full like me

 

[PD]

the only freezer I've got available is the house freezer full o meat ! The wife will moan if I " intrude ". :grin:
When I've bought the wife a new fridge I will have a complete fridge available to me alone...mwhahahaha...... so I think 500ml bottles are going to have to do.

 

[Swift Pint]

I would freeze them.

50% washed yeast, 25% glycerine. 25% boiled cooled water. Put into sterilised sample tubes. :thumb:

Grays, is the glycerine to stop the yeast being killed by the freezing? That sounds like a good approach, how long are they viable for when freezing? I'm going to have to look into this. Great way of getting more brews out of a vial of liquid yeast.

 

[PD]

a collection of 500ml bottles soon takes up quite a bit of storage space in the fridge !
Anyone know if keeping some in smaller sample bottles would work for a fridge ?
Or is the volume too small to survive the cool conditions and would there be enough viable yeast for a brew ?

Urine sample jars are I believe 30mm

 

[graysalchemy]

I would freeze them.

50% washed yeast, 25% glycerine. 25% boiled cooled water. Put into sterilised sample tubes. :thumb:

Grays, is the glycerine to stop the yeast being killed by the freezing? That sounds like a good approach, how long are they viable for when freezing? I'm going to have to look into this. Great way of getting more brews out of a vial of liquid yeast.

Freezing causes ice cystals forming inside the cells. I believe the glycerine lowers the freezing point of the water thus lowering the likely hood of ice crystals forming inside the yeast cells.

I think that is right but I may be wrong perhaps a biochemist can enlighten us.

 

[bunkerbrewer]

a collection of 500ml bottles soon takes up quite a bit of storage space in the fridge !
Anyone know if keeping some in smaller sample bottles would work for a fridge ?
Or is the volume too small to survive the cool conditions and would there be enough viable yeast for a brew ?

Urine sample jars are I believe 30mm

Yep, I use 50ml test tubes in an undercounter fridge - these are cheaply available on eBay. I end up with several tubes containing about 20ml of washed yeast in each from each brew, and a few of these in a starter works really well - better than the first generation.

There's a recent thread here: http://thehomebrewforum.co.uk/viewtopic.php?f=31&t=37991

 

[Swift Pint]

Freezing causes ice cystals forming inside the cells. I believe the glycerine lowers the freezing point of the water thus lowering the likely hood of ice crystals forming inside the yeast cells.

I think that is right but I may be wrong perhaps a biochemist can enlighten us.

That sounds like it makes sense :lol:

I'm pretty keen to give this a try and am looking into getting some kit together. I'll probably start with a vial of whitelabs rather than using slurry.
What do you use for getting the yeast from the slurry/vial/whereever into the test tubes?
I've got a couple of plastic pipettes I use for measuring out water treatments, but I dont think I'd trust them to be sanitary enough.
Is a scientific glass pipette with one of those big squeezey red balls going to be overkill?

What else would you recommend?
I'm going to get a:
1l erlenmeyer flask
some sort of pipette
some glycerine
DME
Vial of White Labs yeast
Plastic test tubes - any recomendation on size - presumably bigger is better for cell count when using & stepping up.

What have I forgotten?
Oh, do you work near a flame/burner to stop bad juju falling into the tubes and causing infections? :hmm:

 

[rpt]

Urine sample jars are I believe 30mm

That's 12 inches. I think there's a joke here somewhere.

 

[PD]

nope...your just like a woman...30cm is 12 inches 30mm is about an inch and a bit in old money

 

[rpt]

nope...your just like a woman...30cm is 12 inches 30mm is about an inch and a bit in old money

Oh yes. However, there's a related joke there.

 

[alanywiseman.]

Freezing causes ice cystals forming inside the cells. I believe the glycerine lowers the freezing point of the water thus lowering the likely hood of ice crystals forming inside the yeast cells.

I think that is right but I may be wrong perhaps a biochemist can enlighten us.

Here is an interesting table. SO at a ratio of 50% washed yeast, 25% giycerine and 25% water the freezing point will be about -4C (assuming that there is water present in the washed yeast).

Would it not be better to increase the amount of glycerin so that the freezing point was below that of the freezer therefore preventing any crystals forming and increasing the viability of the yeast once warmed up to room temp?

 

[Dronfieldbrewer]

I would freeze them.

50% washed yeast, 25% glycerine. 25% boiled cooled water. Put into sterilised sample tubes. :thumb:

Grays, is the glycerine to stop the yeast being killed by the freezing? That sounds like a good approach, how long are they viable for when freezing? I'm going to have to look into this. Great way of getting more brews out of a vial of liquid yeast.

Freezing causes ice cystals forming inside the cells. I believe the glycerine lowers the freezing point of the water thus lowering the likely hood of ice crystals forming inside the yeast cells.

I think that is right but I may be wrong perhaps a biochemist can enlighten us.

I tried it with Abbeydale's yeast with 20% glycerine and it failed drastically...I think that you need a bucket full of glycerine for it to work

 

[dennisdk2000]

I would freeze them.

50% washed yeast, 25% glycerine. 25% boiled cooled water. Put into sterilised sample tubes. :thumb:

Grays, is the glycerine to stop the yeast being killed by the freezing? That sounds like a good approach, how long are they viable for when freezing? I'm going to have to look into this. Great way of getting more brews out of a vial of liquid yeast.

Freezing causes ice cystals forming inside the cells. I believe the glycerine lowers the freezing point of the water thus lowering the likely hood of ice crystals forming inside the yeast cells.

I think that is right but I may be wrong perhaps a biochemist can enlighten us.

Now, I'm no biochemist, but I've been doing some research on freezing yeast after reading Yeast by White and Zainasheff, and basically, glycerine (or glycerol as the Americans like to call it) acts as a non-toxic anti-freeze, working by interrupting the the formation of hydrogen bonds between water molecules as the temperature of the aqueous solution drops below 0°C. This means that crystals won't form until the temperature drops down below the freezing point of pure water.

Freezing causes ice cystals forming inside the cells. I believe the glycerine lowers the freezing point of the water thus lowering the likely hood of ice crystals forming inside the yeast cells.

I think that is right but I may be wrong perhaps a biochemist can enlighten us.

Here is an interesting table. SO at a ratio of 50% washed yeast, 25% giycerine and 25% water the freezing point will be about -4C (assuming that there is water present in the washed yeast).

Would it not be better to increase the amount of glycerin so that the freezing point was below that of the freezer therefore preventing any crystals forming and increasing the viability of the yeast once warmed up to room temp?

I make that -7.0°C assuming that the entire 50% of yeast slurry is water (worst case scenario), 25% water added (75% total water) and 25% glycerine, and assuming the percentages are by weight, not volume (the table uses weight). However, the point still stands that this isn't enough glycerine to prevent freezing of the solution in a domestic freezer.

The procedure in Yeast for freezing at -20°C uses 50% glycerine by volume to 50% media (but I suggest water could be used just as well) - that should result in a freezing point below -23.0°C, so such a solution would remain liquid. They first centrifuge the slurry, discard the liquid and re-suspend the yeast pellet in the glycerine/media (or glycerine/water) solution. They also suggest adding ascorbic acid at a rate of 1g/L - this is meant to improve viability, but that may not be a big issue for most, and I believe it's fairly expensive to get cell culture grade ascorbic acid.

As an interesting note, the procedure for freezing at -80°C uses 15% glycerine by volume to 85% media, giving a freezing point of just below -3.1°C - that one I can't quite explain!

Dennis

 

[alanywiseman.]

As an interesting note, the procedure for freezing at -80°C uses 15% glycerine by volume to 85% media, giving a freezing point of just below -3.1°C - that one I can't quite explain!

Dennis

It does beg the question what is the media? Can't be water.

 

[jonnymorris]

There is an interesting write up here homebrewtalk.com/entries/freezing-yeast.html which discusses the freezing of yeast. The author apparently tested glycerine concentrations from 7.5% to 50% and found 7% to 15% to be optimal for maintaining viability.

 

[PD]

One of the 6 split yeasts I made ( s-04) I've removed from the fridge to warm up a little and will be making a starter from it later today for a brew on Saturday.
Lets see how it gets on.

will be fermented with 300ml of water and 40gms of DME ready for adding to the brew

 

[dennisdk2000]

As an interesting note, the procedure for freezing at -80°C uses 15% glycerine by volume to 85% media, giving a freezing point of just below -3.1°C - that one I can't quite explain!

Dennis

It does beg the question what is the media? Can't be water.

In both protocols they use YPD media (10g yeast extract, 20g peptone, 20g glucose/dextrose) dissolved in water and made up to 1L. This still doesn't explain why they use a 15% concentration for freezing at -80°C, but it would be impossible for any glycerine/water mix not to freeze at -80°C. However, this might:

There is an interesting write up here homebrewtalk.com/entries/freezing-yeast.html which discusses the freezing of yeast. The author apparently tested glycerine concentrations from 7.5% to 50% and found 7% to 15% to be optimal for maintaining viability.

Dennis

 

[PD]

I think DME powder should be listed under the same annoying category as expanding foam !

Bloody stuff.