Let's Freeze Some Yeast

[Midnight Brew]

I've been lurking over this thread for some time and I've gathered most of the materials needed. The only thing missing is an inset for my pressure cooker (an old one from my mom) so that nothing is standing on the bottom surface.

Since I have 2 Wyeast smackpacks in the fridge that I will not be able to use very soon I was thinking of freezing them. I do have some last questions, though:

1. Does anyone knows how much yeast (in ml) is in a smackpack? It says "125ml", but is that including the nutrients?
2. Should I smack the packs and let them swell before freezing? Or only freeze the yeast that is in there? (I want to avoid making a starter if possible...)
3. Am I correct that you should make a mix of yeast, glycerine and water or beer?
4. What is the "optimal" ratio of yeast, glycerine and water/beer?

Voila... If I know the answers on these questions I'm ready for a frozen yeast bank!

Cheers!
- Niels

1. I could be wrong but I think it is 25ml of yeast at 4 billion cells per ml = 100 billion cells.

2. I dont think it matters but generally if smacked it gives you a good indication that the yeast is alive and well so why not.

3. You want a mix of water and yeast (water + yeast = volume) then add onto that the percentage of glycerine you will be using.
Eg 40ml water + 40ml yeast = 80ml + 15% glycerine (12ml) = 92ml.

4. Depends on the resources you look at there are different answers. Plenty of brewers use 10-15% with success and plenty use up to about 50% with success. I originally read that over 15% can be detrimental to yeast and Yob has well and truely proved that to not be the case. Read up on the resources linked in this thread and decide for yourself :icon_cheers:

 

[niels]

Thanks for the quick reply.

Assuming 25ml of yeast in a pack I could go with the following: 25ml yeast + 25ml demi water + 10ml glycerine (20%) = 60ml
Having 20ml vials I can pour this in 4 vials at 15ml a vial...

Sounds like a solid plan, doesn't it?

- Niels

 

[Yob]

From a smacked pack, I got 5 vials of 25ml which ended up about 5ml yeast in each.

To this I added a %50 solution of glycerine to give me a %25 final solution. At %25 they have still frozen solid, but that seems not to matter.

Have a good read through the while thread mate, there is plenty of info on different ratios etc.

You will need to make starters.

 

[niels]

From a smacked pack, I got 5 vials of 25ml which ended up about 5ml yeast in each.

To this I added a %50 solution of glycerine to give me a %25 final solution. At %25 they have still frozen solid, but that seems not to matter.

Have a good read through the while thread mate, there is plenty of info on different ratios etc.

You will need to make starters.

Sorry for my ignorance, but I'm not a native English speaker and sometimes I misinterpret basic things.

If I understand you correctly you have smacked the pack which resulted in 125ml of slurry. Divided over 5 vials gives you 25ml/vial with approximately 5ml of yeast per vial.

On this you added 25ml of glycerine mixture (50% glycerine and 50% water) per vial. This totals to 50ml per vial constisting of 25ml yeast slurry, 12.5ml glycerine and 12.5ml water.

Correct?

Regarding my starter statement: Of course I will have to create starters from the frozen vials, but I meant that I didn't want to make a starter of the smackpack and harvesting that yeast for frozen storage.

I started re-reading the thread and making notes, but I'm always nervous for my first time So I wanted some confirmation and avoid flushing two healthy smackpacks down the toilet.

- Niels

 

[mofox1]

Nutrient pouch is around the 25ml mark. Chose not to smack, and got 3 50ml vials to around 2/3 full prior to adding glycerine.

 

[Yob]

That's all correct neils, spot on.

I got some yeast this week cheaply that are just out of date, so I'm making starters for them to revive them and ensure they are at maximum health when frozen.

 

[MartinOC]

Yob, how big are you doing those "reviver" starters & how/do you allow for extra cell-counts in the resulting slurry?

Or, are you making a starter, decant/wash to ensure you're getting live yeast to freeze & discard obviously dead cells?

Or RDWHAH??

 

[Yob]

Technically I probably should rinse, you do get the opportunity from the starter flask, but to date I've not been overly concerned.

 

[niels]

Nutrient pouch is around the 25ml mark. Chose not to smack, and got 3 50ml vials to around 2/3 full prior to adding glycerine.

Wow, this means it contains about 100ml of yeast and only 25ml of nutrients.

If so I can split a pack over a lot more vials.

- Niels

 

[Yob]

Yob, how big are you doing those "reviver" starters & how/do you allow for extra cell-counts in the resulting slurry?

Or, are you making a starter, decant/wash to ensure you're getting live yeast to freeze & discard obviously dead cells?

Or RDWHAH??

From a vial or pack that isn't too far out of date, I go into a 500ml flask 10 ~1030 wort for 12-24hrs and then into a 2lt flask.

Wow, this means it contains about 100ml of yeast and only 25ml of nutrients.

If so I can split a pack over a lot more vials.

- Niels

You'll find that there is ~125ml total volume (inclusive of the pouch), with about ~25-30 ml yeast solids in that

 

[mofox1]

Wow, this means it contains about 100ml of yeast and only 25ml of nutrients.

If so I can split a pack over a lot more vials.

- Niels

^100ml of yeast suspension (incl water).

I wouldn't have wanted to split it over more than the 3 vials I did, it was looking pretty thin and after it had compacted down it looks like there's only about 5ml or so of solids in each.

Then again, maybe I got the runt of the batch...?

 

[mofox1]

Slightly OT, but all the interested folk are probably here... I'm thinking of buying some more 50ml tubes from proscitech.com. Including delivery, it's around 63c ea if I get 100, or 54c ea for 200 etc.

I would have preferred 25 or 30ml tubes, as the 50ml ones seem HUGE... but can't seem to find them anywhere. So 50ml it is.

Any interest in a bulk buy? Or are there better deals to be had elsewhere?

 

[MartinOC]

What you're looking for from Proscitech is the LS22-30 or 30L (labelled). Scroll down a bit.

I got some of those, but most people went for the LCA03 (50ml) in the last BB I organised through Proscitech. Bags of 50 for about $22??

WHATEVER you do, DO NOT got for anything made from PET & expect it to survive autoclaving (or even hot water). Chemical sanitation ONLY for those babies!!

I subsequently found a place local to me in Melb. that had the exact same things cheaper & I could collect, so no postage. http://www.fusionscientific.com.au/product01.html

Maybe check them out & ask for prices?

Alternatively, there's heaps of stuff on Evilbay, but check you're getting HDPE (ie. Autoclavable), which means they can be re-used & sterilised in a pressure cooker.

Freestanding tubes will make life easier for you, unless you buy a stand to work with them (once they're in the freezer, it doesn't matter).

 

[mofox1]

Cheers, missed those 30ml ones. Have already contacted fusion... Waiting.
Wasn't sure I wanted to go eBay for these, mostly because I want to have at least some assurance that they will be sterile, and made of the material they are advertised as!

 

[Mardoo]

Hey Martin, maybe you could pop those up on Yob's Bulk Buy Suppliers thread?

 

[MartinOC]

He's already beaten you to the punch by a couple of hours

I'll get to it later this arvo.

 

[niels]

^100ml of yeast suspension (incl water).

I wouldn't have wanted to split it over more than the 3 vials I did, it was looking pretty thin and after it had compacted down it looks like there's only about 5ml or so of solids in each.

Then again, maybe I got the runt of the batch...?

Ok, it looks like I might run into troubles if I use my 20ml test tubes.

If I would use the yeast suspension straight from the pack and add glycerine to it I would end up with e.g. 100ml yeast suspension + 30ml glycerine = 130ml solution.

Dividing this over 20ml test tubes I will end up with 7 filled tubes but only 3.5ml of yeast per tube.

Do you think it is doable to dump this 20ml in e.g. a 30ml 1.030 starter as the first step for a starter?

- Niels

 

[MartinOC]

Absolutely, Niels!!

In theory, you can start anything from a single cell, so it's just a matter of stepping-up your starters until you have what you need. A stir-plate will make this easier.

 

[mofox1]

I subsequently found a place local to me in Melb. that had the exact same things cheaper & I could collect, so no postage. http://www.fusionscientific.com.au/product01.html

Maybe check them out & ask for prices?

Prices for those guys are $7.50 for 50 x 50ml self standing, and $9.50 for the 50 x 30ml self standing... the 50ml has a screw on lid, but the 30ml is a "push" on lid (not too keen on that for some reason).

Postage $13 for up to 10 packs of 50.

I've emailed the guy for one pack of the 50ml... Still got time to add more to the order, so PM me if you:

• Are in the eastern/south eastern 'burbs of Melbourne, or
• Like a long drive for few dollars saving, or,
• Can't resist the opportunity to see me in my natural environment

 

[Yob]

Make sure they can be autoclaved, and also have legible markings on the side.. If those are both winners, I'll take 50