Yeast Expert Advice- Agar Slope And Other Points

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There's a phd student up the hallway who's studying biofuel production. I've just picked his brains with regard to yeast techniques. He's suggested a couple of things to try.

His going to get me some agar slopes. These are disks of Jelly that allow the yeast to consume and grow over the whole disk. Place some yeast on the disk, allow it to grow over the whole disk at the right temperature. Then when kept in the fridge should last over a year. The advantage of these is they highly concentrate the yeast, so you should be able to slice off a small fraction of jelly to put in a starter to start a brew. And then keep the same disk to start many brews.

He suggested to wash yeast sludge with a saline solution (0.35% salt) as using fresh water will damage the yeast through osmosis.

He also suggested that if enough moisture is removed from a yeast cake then it should be able to be kept in the freezer for re use.

I guess everyone has different techniques of keeping there yeast but I hope these pointers helped.

Anyway, if anyone has some questions for the yeast guy let me know.

 

[Malted]

His going to get me some agar slopes. These are disks of Jelly that allow the yeast to consume and grow over the whole disk. Place some yeast on the disk, allow it to grow over the whole disk at the right temperature. Then when kept in the fridge should last over a year. The advantage of these is they highly concentrate the yeast, so you should be able to slice off a small fraction of jelly to put in a starter to start a brew. And then keep the same disk to start many brews.

He suggested to wash yeast sludge with a saline solution (0.35% salt) as using fresh water will damage the yeast through osmosis.

He also suggested that if enough moisture is removed from a yeast cake then it should be able to be kept in the freezer for re use.

I guess everyone has different techniques of keeping there yeast but I hope these pointers helped.

Anyway, if anyone has some questions for the yeast guy let me know.

Wow slopes sound good. Can you grow them in rasberry jelly, I like rasberries!

Quite a lot of folks on here grow yeast on agar jelly slants in test tubes with screw top lids or bungs. Set agar agar jelly (mixed with some wort) appears to be indiscriminate about who it lets feed on it so you want to keep any airborne nasties out of it - petri dishes could potentially allow others in. The advantage seems to be that you can select a single colony of healthy yeast to grow in a starter and thus ensuring that it is only yeast growing. Have a read up about yeast slants on this forum. And you'll find information on all of those topics on this forum too, it does not appear to be anything new.
I am not meaning to chuck shit at you. It has obviously sparked an interest in you. I am just saying that there is quite a lot of information in regards to these topics already on this forum.

Edit: if you want to go down that path then scab as much agar agar powder from the guy as you can, bugger the 'disks'. It is quite expensive stuff to buy in small quantities.

 

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Wow slopes sound good. Can you grow them in rasberry jelly, I like rasberries!

Quite a lot of folks on here grow yeast on agar jelly slants in test tubes with screw top lids or bungs. Set agar agar jelly (mixed with some wort) appears to be indiscriminate about who it lets feed on it so you want to keep any airborne nasties out of it - petri dishes could potentially allow others in. The advantage seems to be that you can select a single colony of healthy yeast to grow in a starter and thus ensuring that it is only yeast growing. Have a read up about yeast slants on this forum. And you'll find information on all of those topics on this forum too, it does not appear to be anything new.
I am not meaning to chuck shit at you. It has obviously sparked an interest in you. I am just saying that there is quite a lot of information in regards to these topics already on this forum.

Edit: if you want to go down that path then scab as much agar agar powder from the guy as you can, bugger the 'disks'. It is quite expensive stuff to buy in small quantities.

No shit chucked I knew this stuff would be around, but I find this is sometimes a rather difficult forum to search and find useful stuff (especially when I'm calling them slopes instead of slants). And this forum isn't as anal about revisiting old material as other forums I've been too. Hopefully I can get some comment on how good using slants is and pointers from people who use it for brewing and not producing biofuels. It seems very appealing to me.

Also I'm willing to bet there's a lot of people on this forum still spending $15 a pop on yeast and if a new thread comes up saying they don't have to then it's pretty useful.

 

[Wolfy]

There's a phd student up the hallway who's studying biofuel production. I've just picked his brains with regard to yeast techniques. He's suggested a couple of things to try.

His going to get me some agar slopes. These are disks of Jelly that allow the yeast to consume and grow over the whole disk. Place some yeast on the disk, allow it to grow over the whole disk at the right temperature. Then when kept in the fridge should last over a year. The advantage of these is they highly concentrate the yeast, so you should be able to slice off a small fraction of jelly to put in a starter to start a brew. And then keep the same disk to start many brews.

He suggested to wash yeast sludge with a saline solution (0.35% salt) as using fresh water will damage the yeast through osmosis.

He also suggested that if enough moisture is removed from a yeast cake then it should be able to be kept in the freezer for re use.

I guess everyone has different techniques of keeping there yeast but I hope these pointers helped.

Anyway, if anyone has some questions for the yeast guy let me know.

I find that yeast stored on agar slopes/slants lasts for 'up to a year' after a few months the yeast starts to die and after a year the agar slope has also started to dry out, they are not usually in good condition after 1 year of storage.

I've never read/seen any mention in relation to washing yeast with a saline solution, and I'm sure it would have - at least - been mentioned in the new 'Yeast' book - given the authors and content of said book - if it was better than washing yeast in water.

It would be impossible to remove the moisture (enough) on a home/home brew scale dry then freeze the yeast from the yeast cake, there is also a significant amount of stress and death for the yeast when doing such, and only some strains of yeast can be successfully dried and then retain the characteristics required. On a small/home scale most people freeze yeast samples wet by including glycerin to prevent the yeast cells rupturing when frozen.

There are many very useful published book and online resources specific to brewing-yeast, that would appear to be more useful than a random "a phd student up the hallway who's studying biofuel production" including numerous linked from this forum, however if you are unable to find any in your own searches, let me know and I'll dig some up for you.

 

[dj1984]

Maby a bit OT but last week a managed to get yeast from a slant that was over a year old onto new slants and they seem fine... So IMO test tube slants seem to be the go.

 

[jakub76]

Plenty of good info about yeast slants on this site and others. Following is the list I saved when I researched the topic...thanks Wolfy.

http://www.aussiehomebrewer.com/forum/inde...107&hl=agar

http://www.aussiehomebrewer.com/forum/inde...430&hl=agar
http://www.maltosefalcons.com/tech/yeast-p...s-and-practices
http://brewery.org/brewery/library/yeast-faq.html
http://www.alsand.com/beer/yeast/index_E.html
http://hbd.org/brewery/library/SterileDW1096.html
http://braukaiser.com/wiki/index.php?title...g_Plates_Slants
http://www.realbeer.com/spencer/yeast-culturing.html
http://www.tigereye.net.au/bluedog/slants.html

 

[Wolfy]

Maby a bit OT but last week a managed to get yeast from a slant that was over a year old onto new slants and they seem fine... So IMO test tube slants seem to be the go.

Someone on the JBK (UK) Forums, said he's been reusing the same commercial (Brewlab) yeast slant/slope for the last 4-5 years, so it's possible, however I think it's best to assume they have a fridge-life of no more than a year.

 

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Just reading your threads wolfy, very good info

 

[RobW]

I reculture my slants onto fresh media every 6 months or so.
They can last a lot longer than that, but it's better if you can avoid it.
However I get commercial slants for nix so regular subbing is not really a problem.

Also have a search on YouTube for "aseptic laboratory technique".
There are a number of good vids that show the correct procedures to use.