I would probably put it in a canning jar and boil the jar in water. Boiling 100 % glycerol is probably not a good idea and boiling diluted glycerol will make it hard to know its final concentration. This will be more controllable in a canning jar.
Would this glycerine be good for freezing yeast? not sure after reading the material safety sheet. The price is pretty good.
http://www.newdirectionsaromatics.ca/glycerine-vegetable-usp-995-p-540.html
Apparently styrofoam coolers are NOT a good choice for holding isopropyl alcohol. I had a styrofoam cooler filled with isopropanol in the freezer since the weekend and when I came back to it today all the isopropanol had leaked out and made a huge mess. I had a somewhat similar thing happen the first time I froze cells but I thought my cooler just had a hole in it. Now I'm pretty sure the isopropanol breaks down the styrofoam and leaks out.
For freezing cells, use a PLASTIC cooler filled with isopropanol to slow down the cooling rate. DO NOT USE STYROFOAM!!!
I'm buying glycerol in drugstore and it is sterile, if you're not sure just boil it for few minutes with foil on top (mixed w/water).
What is about v/v vs. w/v dilutions?
I've been using w/v but now I'm not sure about it.. on other hand it depends on what % of gycerin/water solution we use.
I did a little math and it seems that 12% v/v dilution equals to 15% w/v.
When searching about this topic I found article where 10% v/v (12% w/v) is used, samples are frozen to -80°C:
http://nbimcc.org/JCC/2002/JCC312.pdf
Do you think there should be difference in mixing percentage depending on storage temperature (eg -20 vs -80 °C)?
Same here. Growing up a starter of SD Super Yeast right now. Grew a double starter. One of them goes in the brew this weekend, if I get to it. The other gets broken up into tubes and goes in the freezer. No washing, no trub, just nice clean yeast. Those will go to join my stocks of 4 other yeasts including a belgian golden ale yeast, a saison yeast, Ballast Point Sculpin (WLP001) and yeast from Racer 5. That way when you want to brew you just run to the freezer and start yourself a starter. Yeast is a renewable resource. Not so for malt extract, grain and hops, unless you are growing those as well.
I notice in your picture that your yeast looks nice and evenly distributed in the vials. When I checked mine this morning, a lot of the stuff had settled out. Is this normal?
FYI: I just prepared frozen WLP090. I counted them before freezing because there was some question about the numbers of yeast I cited in my article. I found that 20 mls of a thick slurry (a subjective term but lets say easily pourable but noticeably thicker than wort) had 40-50 billion cells (that is about 15 mls of hard packed cells) For my original preparations I used 30 mls of cell slurry and 10 mls of 60% glycerine. That would be 60-75 billion cells. If you are using 50 ml tubes you could easily put 100 billion cells in the tube and adjust to 7.5% glycerol with a concentrated stock. That said, 40-50 billion cells is plenty for an overnight starter.
I thawed some yeast that had been frozen in either 7.5%, 15%, or 30% final concentration of glycerol (v/v). 15% had the best viability and 7.5 & 30% had significantly worse viability.
I would strongly recommend everyone to be using 15% v/v final concentration of glycerol.
4:1 glyerine/slurry would correspond to 25% v/v solution, you may want to lower glycerine to 10-15%.
That 4:1 is when you mix glycerine and water in 60% solution and then add it to slurry in 4:1 rate (60/4=15).
Boil glycerine shortly and sanitize jars, you can mark jars before to know how much to fill them. Always leave some free space in jars for freezing expansion.
Just so I'm clear on this... If I have a slurry mix that's 1L in size, I'll add 250ml of 60% glycerine solution to that. Right? To get the 60% solution, just mix 6 parts glycerine to 4 parts water, correct?
Not exactly, you would end with 5:1 ratio or 20% (1 L/1.25L =0.8; 0.25/1.25= 0.2), and you want 25% of glycerine/water in total volume.
Do your math this way for 25% (or 4:1), it is easier:
Slurry Volume= Total Volume x 0.75
Glycerine/Water Volume= Total Volume x 0.25
Total Volume= sum of above volumes
This gives 937 ml of slurry + 313 ml glycerine/water which is 1250 ml. If you want invariable slurry volume (eg. 1000 ml) then you'll need 333 ml of glycerine/water solution. Total volume is as you see 1333 ml.
You are right about mixing glycerine and water, simplest way to calculate it is to multiply desired total glycerine/water volume with 0.6, you will get required glycerine volume and then top it up with water to desired total volume..
eg. for 500 ml total you need 300 ml (500 x 0.6) of glycerine and rest of it (200 ml) water.
God I hate math... lol
Might be easier to just aim for 1L total volume. IF I'm following you, that would be [simply] 750ml slurry and 250ml glycerine solution. Now, to figure out the glycerine mixture to get that... Looks like 150ml of glycerine and 100ml of water... Right?? It might be easier to make sure the slurry is no more than 750ml, add the 250ml of glycerine solution, and the 'top off' with sanitized water to get the 1L total volume... Good?
I thawed some yeast that had been frozen in either 7.5%, 15%, or 30% final concentration of glycerol (v/v). 15% had the best viability and 7.5 & 30% had significantly worse viability.
I would strongly recommend everyone to be using 15% v/v final concentration of glycerol.
Just wondering... so is this different than the instructions on the front page of this thread?? Or is it the same/similar since one is vol/vol and one is weight/vol? Just a little confused. Thanks!
I thawed some yeast that had been frozen in either 7.5%, 15%, or 30% final concentration of glycerol (v/v). 15% had the best viability and 7.5 & 30% had significantly worse viability.
I would strongly recommend everyone to be using 15% v/v final concentration of glycerol.
It's different. With my original method, I ended up with a final concentration of glycerine of about 20% v/v. I was using 35% w/v glycerine, but I hadn't accounted for the dilution once I mixed it with my yeast slurry. Hope that answers your question.
I thawed some yeast that had been frozen in either 7.5%, 15%, or 30% final concentration of glycerol (v/v). 15% had the best viability and 7.5 & 30% had significantly worse viability.
I would strongly recommend everyone to be using 15% v/v final concentration of glycerol.
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