Propogating yeast

[Hop Farmer]

I had a valve get stuck open while harvesting my yeast and ended up losing most of my healthy yeast from the conical. I'm doing a 2 bbl test batch next week and wanted roughly 2500 ml of 50% solids for my pitch and only ended up with about 500 ml (the rest went down the drain - bummer!). I'd like to do some propogation over the next week to get up to my pitching rate. I've never propogated like this before and from what I read up to a 10 fold increase is safe and I'm below that number which is good. Does anyone have any recommendations on the best process to do a 5 fold increase in about a week?

Matt

[gbrower]

We do propagation here. We blow up 40 times our original pitch rate in 2 days. One key in propagation is to keep the yeast from going fermentative. If you keep them with at least 1 ppm of oxygen and keep them mixing they shouldn't go fermentative. We have a whole system for this(40bbl tank, aerator, air valve controlled by a DO meter) but I'm sure you can put something together with what you have.

I should mention that this makes beer that tastes like cider and is only 0.2% abv.

What you need:

1. A tank that is double the volume of what you will put in. It creates a large amount of head. Even with this you will possible need some sort of anti-foaming agent.

2. A DO meter would be nice but you can go without by guessing.

3. Clean air. You need to oxygenate with clean air. Room air will just create a lot of bugs and wild yeast.

steps:

1. day one: Add 1/4 of the total wort you will need to prop and your yeast.
2. day one: get oxygen going be careful it isn't to high or low. Target should be about 1ppm. You will need to keep this going for 24 hours. This will get the yeast in exponential growth.
3. Day two: add the rest of the wort and keep the oxygen going. Wait 24 hours
4. It should be pretty much done. Cold crash and let settle.

[KTY]

gbrower - are you using pure o2 or filtered, compressed air? If the latter what type of filter are you using?

[gbrower]

We just use filtered atmosphere air. We prop yeast for 500-250 barrels a week so it would be prohibitively costly to use pure O2. In a pinch or at low volumes a little O2 is going to cost less than a whole new pitch of yeast. If you do use pure O2 then you will need to make sure you don't over oxygenate.

The filter we use is a Dominick-Hunter high flow bio-x filter. They are pricy but you can get good life out of them.

[KTY]

We just use filtered atmosphere air. We prop yeast for 500-250 barrels a week so it would be prohibitively costly to use pure O2. In a pinch or at low volumes a little O2 is going to cost less than a whole new pitch of yeast. If you do use pure O2 then you will need to make sure you don't over oxygenate.

The filter we use is a Dominick-Hunter high flow bio-x filter. They are pricy but you can get good life out of them.

Big thanks. I have asked here a few times about air filter recommendations and have never gotten a response so I appreciate your reply!

[Hop Farmer]

Thanks for the help!