Saturday, August 29, 2009

New Plates Are Poured!

Today I'm making up some new blank plates so I can catch up on my yeast sampling.  I've found a variety of recommendations for recipes to make up malt/agar plates on the internet.  Honestly, I didn't write down what I did for my first batch so I can't tell you.  This time my recipe is as follows:

  • 100 grams H2O
  • 1.5 grams agar
  • 1.5 grams Fermaid K
  • 12 grams light DME
I have access to an autoclave at work and use it to routinely sterilize my glassware.  However, things get kind of busy and hectic there so trying to mix up some plate media would be difficult and get in people's way.  I also worry about having agar spill out into the autoclave and make a mess.

Since I don't want to deal with mixing up my media at work I am breaking the rules of sterility and mixing it up stove top. I dissolved the solids in hot H20 and boiled in a sterile 250 ml beaker on my stovetop. This should be good enough to kill any yeasts and most bacteria (except for the spore-formers). If I was using these plates for a commercial application I might be concerned but since they are for my own use I'm taking the"Relax, Don't Worry, Have A Homebrew!" approach.  I will let the plates sit for several days to a week to look for any growth to indicate contamination.

After finishing I realized I might want to make up some more plates to reculture out some of my existing plates since they are getting a little old.  Well one thing at a time....