Tuesday, October 7, 2008

Beer Agar & Broth


This is my current work in progress for a beer agar and broth for culturing yeast samples. The broth is sort of the first step and from that recipe you can just add agar to make plates and slants.

The recipe is in it's smallest form, you can adjust it for size. Generally you should be around a gravity of 1.030 with this formula. I assume this is sufficient, but I don't really have any other reference to go by.

Broth for culturing yeast in a test tube
OG 1.030 - Makes 10ml
  • 10ml water
  • 1g Light Dried Malt Extract (DME)
  • .01g yeast nutrient
Boil 5 minutes and cool. You can adjust the amounts to make larger amounts for starter or multiple tubes.

Beer Agar for Plates or slant
OG 1.030 - Makes 50ml (enough for 5x100mm plates)
  • 50ml water
  • 1g Agar
  • 5g Light Dried Malt Extract (DME)
  • .05g yeast nutrient
Boil 5 minutes and cool to touch swirling often to keep from setting up. Pour about 10ml per plate and tilt to fully cover (do this one at a time or else you'll get at the end and the plates will have already set up).

Use immediately or store in zip top bags in the refrigerator.

2 comments:

Bokonon said...

When I was looking for info on making plates/slants before a lot of the info I found said 1.020 is the preferred gravity. I'm not sure it really matters though.

Deofol said...

Good to know!

I guess 1g to 10ml just seemed so easy to remember and a good starting point. That and I guess most starters shoot for around 1.040, so somewhere in the middle seems like a good number.

But like you said, it may not really matter.