Yeast experiment

[Dronfieldbrewer]

I have been reading another forum about freezing yeast for long term storage and decided that I need to do this. My favorite strain of yeast is Thwaites and is available to me from the brewery directly, however the Brewery is 90 miles away and yeast is only for sale on a Tuesday lunchtime.
I brew commercially monthly, so it goes through me that I throw away approx 2-3 kilos of perfectly good yeast from the fermenter, then end up buying a kilo for the following month. Is yeast freezing the key?
So:-
Rather than cocking up a full brew I have decided to have a go on the little kit.

Here's what I have read:-

1) Yeast is happy to be frozen as long as it is mixed with food grade glycerine. The glycerine acts like a barrier to the yeast cells and the freezing effect and stops some of the yeast cells from bursting under the strain of the freeze.
2) The viability of the yeast after freezing is roughly 50% of what it have been so therefore the amount needed needs to be roughly double.
3) Depending on the temperature of the freezer, the amount of glycerine required is between 15% to 50% of the volume of the yeast.
4) The yeast needs to be frozen slowly and defrosted quickly.

Here's what I have done:-

Sterilized 3 jars.

cropped a job lot of yeast from this brew.

been to Tesco and bought 3, 38ml bottles of glycerine.

So I will be brewing my next brew (Brewers Gold) on the little kit in the near future and trying the frozen yeast..If it works then no reason why I cannot freeze a couple of kilos for the next big brew is there??

 

[Asalpaws]

That does sound very handy, what do you use to store it in the freezer? Tupperware maybe? T

 

[Dronfieldbrewer]

That does sound very handy, what do you use to store it in the freezer? Tupperware maybe? T

To be honest they are in old jam jars. Glass is food grade clearly and can withstand the high temperatures for sterilization.

I sterilize in the oven at a high temperature then cool upside down on a wire rack. My philosophy is that if its good enough for the jam makers in the WI then its good enough for me.

I checked the yeast this morning and its all frozen, but not entirely solid, that must be the glycerine, more like the consistency of good quality icecream

 

[Dronfieldbrewer]

Heres a quick update. I retrieved a jar of yeast from the freezer, left it in the kitchen and brewed 75 litres of Brewers Gold.
I opened the jar to a healthy Pfisst and a good yeast smell. Pitched the lot and now just waiting for the first signs of life

 

[ScottM]

Would slurry not keep in the fridge for a month?

 

[PD]

I've only reused the yeast slurry once and what a cracking quick fermentation it gave. My attempt meant I only kept the slurry overnight in the fridge before use, so I would be interested in splitting the slurry into several batches and freezing if that was possible. I've more or less been advised that I need to mess about washing the yeasts etc and just use the liquid part for freezing, would be nice if I could freeze the whole lot without any messing about.

 

[Dronfieldbrewer]

Would slurry not keep in the fridge for a month?

Not sure it will. I have only kept it for a few weeks and found it smelt a bit funny. If this works it will be brilliant for me

 

[wilsoa1111]

ive kept some slurry in my fridge and sucessfully revived it a year later,

the trick is to keep the temp low and as much water (clean) to yeast as pos, this prevents autolysis i believe (funny smell)

eg the high water to yeast is why washing yeast works well imho

but im not sure is keeping 1+l slurry fresh in 19l of water in the fridge will go down well- maybe alright in the shed this time of year...?

the rate of die off them should be minimal

ps any chance of buying some of that yeast off you next time ur cleaning that fermentor or do a run- rumored to be a classy yeast- unless that breaks some kinda rules?


(also open for a swap, got wyeat 3787, and wlp300 both in v gd nick 2ng gen)

 

[Dronfieldbrewer]

ive kept some slurry in my fridge and sucessfully revived it a year later,

the trick is to keep the temp low and as much water (clean) to yeast as pos, this prevents autolysis i believe (funny smell)

eg the high water to yeast is why washing yeast works well imho

but im not sure is keeping 1+l slurry fresh in 19l of water in the fridge will go down well- maybe alright in the shed this time of year...?

the rate of die off them should be minimal

ps any chance of buying some of that yeast off you next time ur cleaning that fermentor or do a run- rumored to be a classy yeast- unless that breaks some kinda rules?


(also open for a swap, got wyeat 3787, and wlp300 both in v gd nick 2ng gen)

Doesn't break any rules, you can have as much as you want. When it top crops there is about 5-8 kilos of it. Where abouts are you based?

 

[wilsoa1111]

im up in dundee, so probably a post it job,

happy to put up P&P cost (reckon £3 tracked via myhermes) plus whatever for effort via paypal, cant imagine i would need much as i only brew 23l so a 500ml in /2l pet bottles probably the way to go, and should be plenty for a pitch or 2

also got a load of 2011 500g bags marynka or perle from the simplyhops deal if u wanna straight swap if u dont need any of my yeast...

 

[Dronfieldbrewer]

Ohh well back to the drawing board...36 hours after pitching the defrosted yeast nowt...not a bubble or 'owt..... :cry:

Re pitched some fresh stuff....

 

[wilsoa1111]

hmm this does not bode well for my yeast bank- how many mls of glycerine to total liquid/yeast did u use- think u need a 25:75 ratio (or 1:4)...

 

[lukehgriffiths]

Wheeler recommends using high strength bottled ale to reculture yeast.
I am run off my feet but have no probs culturing thwates yeast from nutty dark (or other ales).
My next experiment will involve bottling an IPA as a yeast bank.