Propagating lager yeast for a maibock

[TimL]

I made a starter yesterday and pitched a vial of 833 at my ferment temp of 40-45.

I was hoping to double it up every two days and pitch into cold oxygenated wort next Monday evening.

I was referring to Jamil's page where it says you can expect yeast to double up in 12-18 hours. But I heard on the Maibock show that everything in the lager world that has to do with yeast takes twice as long. So to double up should I wait 36 hours to repitch my yeast to more starter?

As luck would have it, one of my brother's hard drives died over the weekend, so I'm going to make a homemade stirplate tomorrow. I was wondering if anyone had tried using rechargable batteries instead of an AC converter? Would this work at lager ferment temps or should I stick to wall power?

[Speyedr]

Growth will take longer at those temps. I just "grow" at higher temps (room+), then drop the temp in the fridge, decant the "beer" and pitch at Lager temps, but that's me. If you want to grow at Lager Temps, then you will need more time to do it and 36hrs seems like long enough IMHO.

I don't know squat about rechargeable batteries' useful temps though..

[Bugeater]

I think you have a little confusion going on there about "doubling up". Jamil is right about the yeast doubling in volume in the 12-18 hours, though I would plan on more like 18-24 hours or more if you a growing your starter at lager temps.

It appears you are stepping up your starter. The rule of thumb for stepping up is a 10 fold increase in starter volume each time. So if you started by pitching the pack of yeast into 16 ounces of starter you could step it up with as much as 5 quarts (160 ounces) on the first step up. This should get you close to the recommended starter volume. Also this will give you a few more days before brewing to make sure the starter ferments out.

I don't know the temperature limits for rechargeable batteries either, other than any batteries will die quicker in cold temperatures.

Wayne
Bugeater Brewing Company

[TimL]

I'm trying to grow the yeasts at lager temps as recommend by Jamil on his proper yeast pitching rates page. I've listened to a couple of his shows and he's a big proponent of keeping the yeast at around the same temperature you're going to pitch at. Luckily I have a week to wait. Speyedr, maybe I will try your way with my next lager and propagate warm, then chill down.


About stepping up- I actually pitched a vial into about a liter and half of starter after reading quotes from the yeast manufacturers on his same page.
But yeah, now that I think about it, if there's not enough wort they will just start fermenting without multiplying.

My assumption is that I will almost double my first pitch when it's done. Then I was going to split the yeast from that batch into two more starter jugs with the same amount of fresh wort, and they should double again.

Which brings me to 4 times my the amount of yeast. The pitching calculator says I need abour 4.9, so I guess I could split one of those again and get to my final 5 times the orginal vial.

The bad thing is I have to expose the yeast to contaminates and sanitation issues each time I repitch. Next time I think I will make a helles in late December or early January and repitch the slurry left over.