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-   -   Frozen Yeast Bank vs. Yeast Slanting (http://www.homebrewtalk.com/f163/frozen-yeast-bank-vs-yeast-slanting-141962/)

shortyjacobs 10-16-2009 01:57 PM

Frozen Yeast Bank vs. Yeast Slanting
 
Ok, so which do you prefer and why?

I'm interested in getting into yeast preservation, and I don't fancy the idea of washing yeast as much, (seems like more of a chance of infection that way?), versus just culturing a set of starter vials from a vial or smack-pack.

I've read all about them (Frozen Yeast Bank, Yeast Slanting), and it seems like these are basically the differences:

Frozen Yeast Bank:
  • Pro - lasts up to a year in freezer or more
  • Special ingredients - Glycerine
  • Con - Not easy to reculture from a vial without making a starter

Yeast Slants:
  • Pro - Can reculture new slants directly from old slants
  • Special ingredients - Agar agar (wokka wokka)
  • Con - Only lasts 3 months (but you can reculture)

Do I have that right? What do you prefer and why?

passedpawn 10-16-2009 03:45 PM

I prefer freezing, but only because i can store them for longer periods. I have at least 50 tubes of various yeast in my freezer. I have never grown on slants.

BTW, I get glycerine at Walmart. It is in with the hand sanitizers and is very inexpensive.

jds 10-16-2009 04:04 PM

ShortyJacobs:

I've successfully made slants for yeast using gelatin and wort, instead of having to hunt down agar-agar. A thick wort/gelatin solution, cooled at an angle in a small vial, makes a workable slant. Also, I've recultured slants that were over a year old.

I'm not saying my technique is great, or that I'm not slowly mutating my strains -- I'm just saying that good results can be had from very modest equipment.

chuggs 10-16-2009 06:51 PM

Agar is just a type of gelatin. Of course for yeasts...you'd make an agar medium that uses Maltose. (DME & Agar) There are different agar mediums for growing different things.

The main advantage of a slant or petri dish with agar is...you use a sterile nichrome wire loop to transfer a streak onto the agar. Individual yeast cells multiply over time, as you incubate...and visible cell colonies appear. When you go to make a yeast starter...you sterilize your loop again...and pick up one colony and transfer it to a sterile wort starter. This makes it easy to get VERY PURE yeast cultures. With other methods...you could have a mix of who knows what in there. You can even buy a microscope and prepare slides to look at your yeast...

It's a pain in the butt to do this though. I kept a yeast bank on mini petri dishes for a few years. I leave all that to the big boys now...and just buy a slap pack. I then chain brew..dumping the yeast from one secondary, into the next primary...untill all my kegs are done... Then I take a hiatus. I buy another slap pack the next time I start the pipeline up again.

passedpawn 10-16-2009 07:06 PM

Quote:

Originally Posted by chuggs (Post 1614477)
Agar is just a type of gelatin. Of course for yeasts...you'd make an agar medium that uses Maltose. (DME & Agar) There are different agar mediums for growing different things.

The main advantage of a slant or petri dish with agar is...you use a sterile nichrome wire loop to transfer a streak onto the agar. Individual yeast cells multiply over time, as you incubate...and visible cell colonies appear. When you go to make a yeast starter...you sterilize your loop again...and pick up one colony and transfer it to a sterile wort starter. This makes it easy to get VERY PURE yeast cultures. With other methods...you could have a mix of who knows what in there. You can even buy a microscope and prepare slides to look at your yeast...

It's a pain in the butt to do this though. I kept a yeast bank on mini petri dishes for a few years. I leave all that to the big boys now...and just buy a slap pack. I then chain brew..dumping the yeast from one secondary, into the next primary...untill all my kegs are done... Then I take a hiatus. I buy another slap pack the next time I start the pipeline up again.

I'd like to try my hand at slants sometime.

BTW, for most > 1.050 beers, one smack pack technically is not enough. At least it is not the proper pitch rate for a fast start to avoid all sorts of admittedly minor flaws. Therefore, you technically still should be making a starter and building up the yeast count. Of course, when you dump you wort onto a yeast cake you have more than enough yeast!

Scimmia 10-16-2009 07:36 PM

Quote:

Originally Posted by passedpawn (Post 1614530)
Of course, when you dump you wort onto a yeast cake you have more than enough yeast!

Which can also be a bad thing.

JKoravos 10-16-2009 08:17 PM

Quote:

Originally Posted by shortyjacobs (Post 1613509)
Ok, so which do you prefer and why?

I'm interested in getting into yeast preservation, and I don't fancy the idea of washing yeast as much, (seems like more of a chance of infection that way?), versus just culturing a set of starter vials from a vial or smack-pack.

I've read all about them (Frozen Yeast Bank, Yeast Slanting), and it seems like these are basically the differences:

Frozen Yeast Bank:
  • Pro - lasts up to a year in freezer or more
  • Special ingredients - Glycerine
  • Con - Not easy to reculture from a vial without making a starter

Yeast Slants:
  • Pro - Can reculture new slants directly from old slants
  • Special ingredients - Agar agar (wokka wokka)
  • Con - Only lasts 3 months (but you can reculture)

Do I have that right? What do you prefer and why?


I think 3 months is a pretty conservative estimate for slant life. at least from what I've read and heard. I just started slanting recently, but my first step up from a slant was over 3 months after I slanted them and there was no issue with getting it going.

giligson 10-16-2009 10:34 PM

Quote:

Originally Posted by chuggs (Post 1614477)
Agar is just a type of gelatin. ...This makes it easy to get VERY PURE yeast cultures. ....

with all due respect:
Agar is a polysaccharide whereas gelatin is a protein - so there is one difference. Also Agar is very sturdy and wont melt until its temp gets near to boiling water and gelatin will start to melt at room temperature. Agar seems expensive when you buy it but you use just a little bit of it and the powder lasts for a long time - its easy to source by mail order. Also a lot of health food stores will stock agar powder.

Picking a yeast colony from a plate or slant will ensure that you get exact duplicates of the primary cell that landed on that spot on the plate but it doesn't guarantee that the colony in question is not a mutant.

Whew...now that the nitpicking is out of the way.
I find slants very convenient; they will last well at least 9 months (haven't tried longer) in a conventional frost free refrigerator (maybe longer in a non frost free model). Its very easy to get a starter going from a slant - yes you still must do a starter- but it takes more time to get a culture up and running from frozen glycerine. I don't know the viability of frozen glycerine yeast in a conventional freezer (temperature cycles for it to remain "frost free" damages the cells) but they will easily last 2 years in a non frost free -20 Celsius old style freezer and can last 5+ years in a -80 research grade freezer.

brewingkitty 09-20-2010 07:53 PM

i have many strains slanted almost a year oldish and they are still the proper color. but soon, i will be re slanting all of them to make sure i have viability, while continuing THESE tubes to actually determine the useful life.

piteko 09-24-2010 10:39 AM

Quote:

Originally Posted by giligson (Post 1615080)
Its very easy to get a starter going from a slant - yes you still must do a starter- but it takes more time to get a culture up and running from frozen glycerine.

Can anybody explain me why it gets more time running a culture from frozen glycerine than from a (maybe frozen) slant? Shouldn't there be many more cells in the glycerine?

Cheers from Italy :mug:
piteko


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