YEAST CULTURING

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YEAST CULTURING

Last year I grew my own yeast (Wyeast 1388) on agar (photo).
This year I want to try again.

Equipment you need

Wort*
Agar Agar
Pyrex Petri Dishes
Pyrex tubes and caps
Parafilm
Pyrex conical flask

*wort come from my last all grain (red ale). I recycled the ending wort coming from sparge (OG < 1020).

FROZEN WORT AND YEAST

 

This is my recipe:

- Agar Agar: 2 g (2%)

- 200 ml of wort with OG: 1025

Initial wort has an OG of 1015.

So you must concentrate wort to obtain a FG of 1025. I boiled it. This operation sterilize it.

 

Now place the pyrex dish and some test tubes mentioned above inside a pot. Put a couple cm of water in there. Crank up the heat so that this water boils (full power will probably not be required), and keep it boiling for 10-15 minutes. If you wish, you can put the vial-caps in there too, or just sterilize them with your favorite chemical agent. What is happening at this stage is that the boiling water is sterilizing the vials, the dish and the caps. 

 

Take 200 ml of wort and put it in the flask. Put the flask into a pot with 2-3 cm of water. Then add 4 gr of agar (2%) and mix.

When agar is dissolved, put the mix into vials and petri dishes and wait for cooling. You must cool the vials while placing them at an angle of about 40-45 degrees.

At this point, the procedure depends on what the source is for your yeast to be cultured. I'll describe doing it from my old petri dish. 

Put your needle/paperclip into a flame to sterilize it. Open the new petri dish (or vial) to be inoculated. Then open the old petri dish with Wyeast. Dip your needle into the Wyeast, and then *lightly* poke it into the surface of the agar + malt growth medium in the new petri dish (or vial). Poke it in a bunch of places. Smear it around. Just try hard not to touch the walls of the vial. When done, withdraw the needle, cap the slant vial or petri dish, and cap the Wyeast old dish. You now have a fully inoculated dish or slant vial. Keep doing this for as many vials as you wish to inoculate.


When done, leave the vials or dishes out at room temperature (20°C) for a week. Within a couple of days you will see a cloudy film on the slant surface, and a few days later it will develop into a milky white layer about a mm thick.



RESULTS

12 hours later

36 hours later

 

48 hours later