Tuesday, November 25, 2008

Cluturing Yeast Pt 2

As promised, here's some more on the latest steps in my yeast culturing project... We left off with a petri dish streaked with yeast from my slurry. Here's what it looks like now:

The next high-level steps are to:

1) Prepare 10ml starters

2) Innoculate those starters with single colonies from the petri dish

Equipment (in addition to what was used in the previous steps):

1) 10ml test tubes - I prepared three starters

2) Airlocks - I treated myself and got some of the fancy glass ones so that I could sterilize them in the canner if needed

3) Drilled stoppers - I was unable to find drilled stoppers that fit test tubes and would accept an airlock, so I was forced to take matters into my own hands. I took stoppers that fit the test tubes and drilled them myself. It's a huge help to have a drill press handy when doing this.

4) Autoclavable test tube rack - Mine has turned out to be not so autoclavable

5) 10ml pipette

6) Prepared sanitizing solution - Use this to fill the airlocks. I just use my handy spray bottle of Star San.

7) Olive oil and a tooth pick.


1) Prepare the starters - Using the same 10brix wort (with a dash each of Five Star 5.2 and yeast nutrient, no agar this time) and the pipette, fill each test tube with 10ml of starter wort. Also at this time, I dip the tooth pick in the olive oil, and put a tiny drop in each of the test tubes. I won't get into that in this space, but here's the rationale behind it (the fatty acids in the olive oil are a substitute for aeration of the wort). Put the stoppers and airlocks in. Fill the airlocks with sanitizer. Presumably you've already got the test tubes in the rack.

2) Sterilize the starters - This is a basic water bath procedure. Place the rack with the starters in your stainless steel sauce pan. Add enough water to the bottom to come about 1/3 of the way up the test tubes. Heat the water to a simmer. Wait for the starters to come up to a simmer and then give them about 10 minutes. Take off of the heat and allow them to cool to room temperature. Now you've got yourself some sterile 10ml starters. Note: at the same time that I'm doing this, I also like to prepare my sterile distilled water for cooling the innoculating loop. Put some distilled water in a small pyrex flask, cover with foil, and let it serilize in the sauce pan next to the rack.

3) Innoculate the starters - Take the starters to the clean, draft free area where your petri dish is hanging out. Put on your dust mask to contain your disgusting germs. Flame and cool your innoculating loop. Open up the petri dish. Quickly grab a small colony from the center of the petri dish with the innoculating loop, quickly open one of the starters, and quickly add the colony to the starter. Quickly put the stopper and airlock back in the starter. Did I mention that you should act quickly? Quickly repeat until all starters are innoculated.

4) Wait - Let your starters culture up in a clean, draft free room temperature environment. You should see activity within a day or two.

Next steps... Once these starters have finshed we'll repeat the above steps with 100ml starters, innoculating them with the 10ml starters.

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