Starting a yeast bank
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I would be very tempted to look at freezing your yeast. Start up cost is very low, like of the yeast is good, up to years, you can store pitchable quantities...
If you visit a couple of local pharmacies and ask if they have any old vaccine shipping boxes (like a mini cool lite broccoli box), these are ideal, some test tubes and food grade glycerine (try cake making supplies at your supermarket) and your on your way.
Good enough place to start reading BYO Yeast Ranching
Mark
If you visit a couple of local pharmacies and ask if they have any old vaccine shipping boxes (like a mini cool lite broccoli box), these are ideal, some test tubes and food grade glycerine (try cake making supplies at your supermarket) and your on your way.
Good enough place to start reading BYO Yeast Ranching
Mark
Coalminer
Well-Known Member
It is well worth the effort to start up a yeast bank by freezing
Have been doing this for 2.5 years now with great success with 50ml vials in a chest freezer (Not an auto defrost type)
Megs888 See PM
Have been doing this for 2.5 years now with great success with 50ml vials in a chest freezer (Not an auto defrost type)
Megs888 See PM
Last edited:
Called in to my local pharmacy today and asked if they had any "Vaccine Shippers" they were happy to hand over this 5L one and a 10L, came with half a dozen of the cool gel packs, the coffee cup and the binder (A4) should give you a fair idea of the size, seen some half the size, some way bigger.
Great little freebee and it keeps them out of landfill.
Mark
Great little freebee and it keeps them out of landfill.
Mark
Mat
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Are there any negative effects of having glycerine in the wort? Flavour, yeast health, attenuation etc
I realise that there's only a very small amount of glycerine per pitch. e.g. 5ml per 50ml tube and then that is then diluted in 20 odd litres of wort.
Any effects would most likely be extremely negligible but I thought I'd ask just in case.
cheers,
Mat
I realise that there's only a very small amount of glycerine per pitch. e.g. 5ml per 50ml tube and then that is then diluted in 20 odd litres of wort.
Any effects would most likely be extremely negligible but I thought I'd ask just in case.
cheers,
Mat
Coalminer
Well-Known Member
I have done my last 40 brews with frozen yeast up to 2 1/2 years with no ill effects,(have trouble keeping up the supply). that is with 12.5 ml glycerine in a 50ml vial
( I use 12.5 glycerine 12.5 water and 25ml yeast slurry) Don't forget that you are stepping up 2 or 3 times and decanting spent wort each time so very little would end up in the fermenter as it is water soluble
Coalminer
Well-Known Member
wide eyed and legless
Well-Known Member
Any chance of writing up a 'How to' Although I have a feeling there was a thread on this
Coalminer
Well-Known Member
Let's Freeze Some Yeast
Discussion in 'Yeast' started by Bribie G, 2/12/10.
Have not been any updates since the purge but I took my lead from this thread and refined the process to suit my circumstances and equipment. I don't have lab grade areas to work in but with due diligence infections can be (almost) eliminated
I am going to do a 'how to' in the coming week and may post it here but real busy at the moment making survival rations ( nothing less than 5%)
Discussion in 'Yeast' started by Bribie G, 2/12/10.
Have not been any updates since the purge but I took my lead from this thread and refined the process to suit my circumstances and equipment. I don't have lab grade areas to work in but with due diligence infections can be (almost) eliminated
I am going to do a 'how to' in the coming week and may post it here but real busy at the moment making survival rations ( nothing less than 5%)
Coalminer
Well-Known Member
Disclaimer: Please note this is NOT a definitive "How-To" guide. I do not profess to know everything about the subject. It is the method I use with information I have gathered over several years on a few threads. I have worked out this method to suit my available equipment and circumstances. I do not have a sterile lab quality environment or equipment, but with due care and attention you can do this successfully in less than ideal conditions.
1: Equipment I use...
S/S saucepan and funnel
Induction hotplate
Pressure cooker
Boroscilicate flasks 250 ml -500 ml - 1,2,3,5 Litre
Chest freezer - non auto defrost if possible
Stir plates and stirbars
Starsan or similar
Autoclavable 50ml centrifuge test tubes and suitable racks
Temperature controlled cupboard (home-made) to build up starters or fridge in summer
Thermometer (Thermapen) and Refactometer
Food grade Glycerine
Aquapura brand water (Woolworths product)
DME
Wyeast smack packs (the fresher the better, mine come from my LHBS usually only about 2 weeks old)
Method: for 1 smack pack
Take a smack pack of 1 month old - 77% viable and build a starter to pitch into a brew, but first overbuilding that starter by 100 Billion cells. Use what's needed for the pitch and use those 100 Billion overbuild cells to split into 5 vials as above.
These fresh cells can be considered to be 100% as they have just grown, then be considered as 80% viable when thawed (say 20% loss due to the freezing process)
Example 3
You can always make a starter with your smack pack and overbuild by a set amount and pitch some to a brew and divide and freeze the rest. I this instance you can regard these cell as almost 100% viable at freezing and 80% at thawing and freeze as many vials as you wish.
A lot of this is somewhat guesswork but seems to work well enough as I don't have a centrifuge or cell counting equipment at present
This process has served me well for nearly 3 years without a lost brew ( 46 to date )
Freezing is really handy to have a stock of your favourites on hand, especially those seasonal PC ones that tend to only be available once a year, and the oldest I have used has been almost 3 years old.
1: Equipment I use...
S/S saucepan and funnel
Induction hotplate
Pressure cooker
Boroscilicate flasks 250 ml -500 ml - 1,2,3,5 Litre
Chest freezer - non auto defrost if possible
Stir plates and stirbars
Starsan or similar
Autoclavable 50ml centrifuge test tubes and suitable racks
Temperature controlled cupboard (home-made) to build up starters or fridge in summer
Thermometer (Thermapen) and Refactometer
Food grade Glycerine
Aquapura brand water (Woolworths product)
DME
Wyeast smack packs (the fresher the better, mine come from my LHBS usually only about 2 weeks old)
Method: for 1 smack pack
- Set up 5 x 50 ml vials in rack
- Fill with 12.5ml water and 12.5 ml glycerine
- Put lids on and shake well to mix
- Release lids a little to allow to breath with expansion and set up in pressure cooker with just enough water to reach the liquid level in the vials
- Cook for at least 15 min at 115oC ( my cooker only goes down to 25 min so that is what they get
- Tighten lids and place in fridge to cool. Can be prepared a few days in advance if need be
- When ready to freeze let vials and Yeast Pack to come to room temperature
- Smack the yeast pack and allow to swell to prove viability - this give you 125ml yeast slurry.
- Sanitize outside of vials and loose lids
- Shake up pack to mix thoroughly and sanitize outside of pack and cut off corner.
- Add 25ml of slurry to each vial, seal and shake to mix everything together
- Place vials in fridge for 24-48 hrs This apparently helps to expel water and absorb glycerine, shaking occasionally
- Place into freezer and freeze as quickly as possible (a blast chiller would be great but I don't have one)
- Keep in freezer as low as possible so they are not left out accidentally when looking for something else
- Keep record spread sheet or written notes with vial ID number, yeast name, date manufactured, date frozen, water-glycerine-yeast slurry volumes, estimated viability at freezing and thawing.
- Thawing:
- Prepare 200ml of 1.020 boiled wort (I normally boil it in a saucepan, chill to about 26oC (for ale yeast) or 20oC (for lager yeast) and add to a small flask
- Defrost yeast vial - faster is better for yeast cells - but don't overheat it just bring up to the wort temp (carry it in your pocket for a few minutes) and add to flask
- Onto stir plate and gently stir for 24 hours
- Rest at room temp for 24 hrs
- Place in fridge for 24 hrs
- Decant spent wort from flask then step up your starter with 1.037 wort to suit requirements - either 1,2,3 steps as reqd to get pitchable quantity
- Assumptions for calculations
- Use a yeast calculator for your calcs I use Dad's Online calculator
- Homebrew Dad's Online Yeast Starter Calculator
- Example 1
- Take a new smack pack, say 1 month old and viability 77% and split into 5 vials of 25ml slurry each = 20x77% = 15.4Billion. Viability when thawed 77% less say 20% loss due to the freezing process = 61% so theoretically 20 x 61% = 12.2Billion - at the date of thawing (use that date in calculator instead of original pack date) use this figure to build starter reqd. i.e. the date you thaw is the new manufacturing date for calcs (it will come out as 97% viable)
eg Dads Homebrew calculator says 200ml then 1.3L to get 224 Billion for a 1050 23L Ale using the thawing date as viability calculation
- Example 2
Take a smack pack of 1 month old - 77% viable and build a starter to pitch into a brew, but first overbuilding that starter by 100 Billion cells. Use what's needed for the pitch and use those 100 Billion overbuild cells to split into 5 vials as above.
These fresh cells can be considered to be 100% as they have just grown, then be considered as 80% viable when thawed (say 20% loss due to the freezing process)
Example 3
You can always make a starter with your smack pack and overbuild by a set amount and pitch some to a brew and divide and freeze the rest. I this instance you can regard these cell as almost 100% viable at freezing and 80% at thawing and freeze as many vials as you wish.
A lot of this is somewhat guesswork but seems to work well enough as I don't have a centrifuge or cell counting equipment at present
This process has served me well for nearly 3 years without a lost brew ( 46 to date )
Freezing is really handy to have a stock of your favourites on hand, especially those seasonal PC ones that tend to only be available once a year, and the oldest I have used has been almost 3 years old.
Just one point, I would probably want to use a bit more Glycol. It's the formation of ice that kills yeast cells either by their exploding just like a bottle in the freezer can, or by ice crystals that form like little needles skewering the cells from the outside.
The later effect is most common when the glycol content is too low to prevent slush formation (slush is ice crystals in suspension).
It will depend on the temperature you are storing at (the colder the better) but say you are at -20oC from the following table -
The 25% glycol in Coalminers method would not be enough, most of what I have seen recommends at least 1/3 glycol (33.3%) and up to 50% for colder freezers.
It is best to keep the frozen tubes in an insulated container (even a 6 pack esky) with a couple of big bricks of gel ice just to keep the storage temperature stable. even smallish temperature changes at close to the slush point can cause ice needles to grow and kill more cells.
Mark
The later effect is most common when the glycol content is too low to prevent slush formation (slush is ice crystals in suspension).
It will depend on the temperature you are storing at (the colder the better) but say you are at -20oC from the following table -
The 25% glycol in Coalminers method would not be enough, most of what I have seen recommends at least 1/3 glycol (33.3%) and up to 50% for colder freezers.
It is best to keep the frozen tubes in an insulated container (even a 6 pack esky) with a couple of big bricks of gel ice just to keep the storage temperature stable. even smallish temperature changes at close to the slush point can cause ice needles to grow and kill more cells.
Mark
Coalminer
Well-Known Member
Sorry my bad
Have been working on the ice bank at work and got the wrong stuff - bit like an ear worm...
Glycerol, same point as above, I would use more than 25%, here is a better look at why.
Have been working on the ice bank at work and got the wrong stuff - bit like an ear worm...
Glycerol, same point as above, I would use more than 25%, here is a better look at why.
Last edited:
Mat
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This is the article where I got the 10% glycerine (5ml per 50ml vial) reference from.
https://www.homebrewtalk.com/freezing-yeast.html
"Glycerin, food grade (must be diluted in sanitized water before use; a rate of 1 part glycerin to 4 parts water gives a 20% final concentration). Glycerin, glycerine and glycerol are all the same thing. See Resource section at the end of this article. See Figure 3. "
"3. Add an equal volume of chilled 20% glycerol to each of the samples of yeast and cap tube tightly. Swirl or stir until fully mixed without frothing. This will lead to a final concentration of glycerin of 10%. Concentrations of glycerin higher than 15% appear to be detrimental to cells when stored at home freezer temperature (20C, -3F). Make sure there is sufficient room for expansion during freezing. "
The way that I understand it is, that the higher concentration of glycerine (25-30+%) would prevent the sample from solidifying at a given temperature, much the same as glycol in cooling systems but this is not the aim of the method. Rather the glycerine solution at the lower concentration (i.e. 10%) would allow solidification whilst the glycerine would prevent the cell walls from rupturing. So the glycerine is acting as a cryoprotectant as opposed to an anti-freeze.
I may be completely wrong here, but that is my understanding. Happy to be corrected though.
https://www.homebrewtalk.com/freezing-yeast.html
"Glycerin, food grade (must be diluted in sanitized water before use; a rate of 1 part glycerin to 4 parts water gives a 20% final concentration). Glycerin, glycerine and glycerol are all the same thing. See Resource section at the end of this article. See Figure 3. "
"3. Add an equal volume of chilled 20% glycerol to each of the samples of yeast and cap tube tightly. Swirl or stir until fully mixed without frothing. This will lead to a final concentration of glycerin of 10%. Concentrations of glycerin higher than 15% appear to be detrimental to cells when stored at home freezer temperature (20C, -3F). Make sure there is sufficient room for expansion during freezing. "
The way that I understand it is, that the higher concentration of glycerine (25-30+%) would prevent the sample from solidifying at a given temperature, much the same as glycol in cooling systems but this is not the aim of the method. Rather the glycerine solution at the lower concentration (i.e. 10%) would allow solidification whilst the glycerine would prevent the cell walls from rupturing. So the glycerine is acting as a cryoprotectant as opposed to an anti-freeze.
I may be completely wrong here, but that is my understanding. Happy to be corrected though.
Coalminer
Well-Known Member
Always keen to learn, I shall read that Mat when I get the chance. (Retirement does not make me less time poor in lockdown)
Actually in my method above, Mark, I am using 25% Glycerine, 25% water and 50% yeast slurry i.e. 12.5ml glycerine 12.5ml water and 25ml yeast slurry.
These solutions do indeed freeze solid and so far have had no failures. Bear in mind I do use a decent overpitch of about 20% in the brew (backyard calcs)
Cheers
Actually in my method above, Mark, I am using 25% Glycerine, 25% water and 50% yeast slurry i.e. 12.5ml glycerine 12.5ml water and 25ml yeast slurry.
These solutions do indeed freeze solid and so far have had no failures. Bear in mind I do use a decent overpitch of about 20% in the brew (backyard calcs)
Cheers
I've just been going through the original work on yeast freezing, worth noting that it was coming into its own in the early 90's. Back then it was all research on storing samples long term (decades - maybe forever if you don't forget to pay the power bill). They were using from 50-100% Glycerol and freezing to -80oC or lower, which might be a bit different to what home brewers are aiming at. Well below the freezing point of even pure Glycerol - so yes they were freezing solid to (I missed that).
Newer work focused of storing pitchable quantities for home brewers appears to have concluded that lower concentrations of Glycerol works, reportedly for storage out to a year or two. Which is quite different to what labs want; small quantities for a long time V Large amounts for a relatively short time.
Looks like the consensus is that somewhere between 10% and 30% works well in home freezers, the colder the better and perhaps at the higher end if you have a really cold freezer (say <-20oC) or want the samples to keep longer.
Sorry if I caused any confusion, haven't read up on the subject or frozen any yeast for a few years (maybe 10), lost my collection in a move and haven't rebuilt it, yet.
Mark
Newer work focused of storing pitchable quantities for home brewers appears to have concluded that lower concentrations of Glycerol works, reportedly for storage out to a year or two. Which is quite different to what labs want; small quantities for a long time V Large amounts for a relatively short time.
Looks like the consensus is that somewhere between 10% and 30% works well in home freezers, the colder the better and perhaps at the higher end if you have a really cold freezer (say <-20oC) or want the samples to keep longer.
Sorry if I caused any confusion, haven't read up on the subject or frozen any yeast for a few years (maybe 10), lost my collection in a move and haven't rebuilt it, yet.
Mark
Coalminer
Well-Known Member
No problem. I am only storing (my estimate) 15-20 billion so have to step up a couple of times
I think I still have some samples about 3 years old that still work
Never bothered using a insulated container but I will soon
I think I still have some samples about 3 years old that still work
Never bothered using a insulated container but I will soon
Coalminer
Well-Known Member
Yes I use these. they are autoclavable at 121oC
Easily cleaned and reusable
https://www.ebay.com.au/itm/10Pcs-5...a=1&pg=2546172&_trksid=p2546172.c101072.m2109
Description:
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