Theoretically???

[Martin the fish]

Could you use a packet of dried yeast and start a 2ltr culture, split it down into 6 x PET bottles-treating them like liquid yeasts and starting them with a pint of cooled wort ready for pitching? Using the last one to re-culture up to 2ltr and split again?

Is the reason home brewers don't do this because of the relatively cheap and easy access of dried yeast or is there another reason like viability?

Also how long is split wyeast packs viable for? Is there a better yet basic way of storing the culture's?

And whats an agar slant???

[agentgonzo]

It should be possible. I think the main reason is that dried yeasts are cheap and it's much easier to just open a new sachet and use it. Less to go wrong. It's not worth spoiling a batch for a £1 sachet of yeast.

People have said that dried yeasts will loose their viability after 3-5 generations or so. Not sure if anyone has stored them long term.

Liquid yeasts spilt into separate PET bottles should be viable for ~6 months maybe - they'll be required to be stepped up before use. For longer term storage, they'll need to be stored in boiled distilled water or gelatin in sterile (not sanitised!) conditions in the freezer.

Agar is a sterile nutrient that is used in chemistry labs to grow a multitude of things - in our case, yeast. If you mix agar with gelatin (I think), you get something a gel that will set hard when it cools. If you put a test-tube at an angle and then put some agar-gelatin mix into the test tube, it'll form a layer of nutrient that you can then use to support yeast. The reason for slanting it is to get a greater surface area to store/grow the yeast on. I'm sure a chemist will correct me if any of the above is wrong/confusing.

[johnh]

Here is an excellent article explaining what slants are and how to prepare them with very basic equipment.

My test tubes arrived this morning so I'll be giving it a go this afternoon!

SWMBO has threatened to throw out my coveted 'bottles with gunk' from the fridge. So hopefully this will keep her happy.

[Martin the fish]

So really you'd be better off just buying some more.

I think i'm ok for yeast for the moment. But it is something that i have thought about.

[flytact]

It depends on how cheap it is over there and how easy it is to get over there weighed up against the cost of your time, the wort and the risk of infection.

At around a quid fifty for a packet or less over here it's not worth the effort.

Exactly. I've been known do dump onto an old S-04 yeast cake, but easier to just rip the packet and have at it!

[agentgonzo]

Exactly. I've been known do dump onto an old S-04 yeast cake,

Now that's a way to instantly ruin your yeast cake...

[steve_flack]

I wonder if it means the same in 'American English'.

BTW, to MTF. An agar slant is a mixture of agar and malt extract in water that has been heated up to give a solution. This sets like a jelly when it's cooled and you can grow yeast on the surface of the jelly. You can also use gelatine instead of agar but agar is better. I've got a supply of an agar with the malt extract already in it. I use about 4g in 100ml of water IIRC.

This is another good reference.

[Martin the fish]

I wonder if it means the same in 'American English'

I've got that link. I thought it was quite good-nice to have it confirmed.
I think i'd like to have a go at agar slants and yeast loops and the like...