Farming

[mgeltzei]

Is it possible to make an overly large starter and then save a percentage of that for a future starter? This seems easier and more sanitary than trying to harvest from a carboy. My only concern would be that you have fermentable sugars in solution and could potentially build up CO2 in your storage container. John Palmers mentions not wanting to store yeast with an aluminum foil cover to prevent oxygenation but then on Brew Strong he notes leaving his storage jar partially unscrewed to prevent pressurization. Do you think that there's really a difference in the amount of oxygenation with a foil cover and rubber band versus a partially unscrewed cap?
Thanks

[anday6]

I started doing this but I let the started finish out before taking out the saved yeast. I decant, swirl, pitch the slurry and save a few ounces. That portion goes in a small, sterilized mason jar. I top it up with boiled, cooled leaving now head space. This is storing a mostly pure yeast slurry under clean water.

This yeast only sees a starter cycle and some osmotic stress from the water. I've built up a pitch after a month or two with no problem. It might just take an extra step to grow up enough cells. Viability is tough to predict so I mostly go off the volume of slurry. Not exact but I always over-pitch by eye and make sure the yeast is nice and active before pitching.

[spiderwrangler]

My only concern would be that you have fermentable sugars in solution and could potentially build up CO2 in your storage container

Here you'd be talking more about the 'chill and decant' school of starter making rather than the 'pitch at high krausen' method. As Anday said, the vast majority of the sugars will have been consumed, so the yeast shouldn't be doing much combined with the cold.

[Ozwald]

Definitely let it finish if you're going to be doing something like this. If you don't, you're almost guaranteed to have problems. What I was doing for my yeast experiments was to build a pitch up into a couple gallon starter. As soon as it would finish out I'd have several hundred mL of slurry. After a quick rinse, I would divy it up into 50mL samples, either in mason jars or growlers. I could take any one of those & build it to a regular pitch very easily. For the experiments, I'd often repeat the process, building one of the 50mL off-shoots into a couple gallon starter, rinse, split & do my tests. Don't let it get too out of hand, as you'll find yourself with a part-time job just caring for the yeast. I've also heard of folks doing a fairly similar method when they live somewhere where it's difficult to obtain vials. I think one wrote into the show from Brazil saying he propped 1 vial up to make several vials so he didn't have to pay high shipping costs every time he needed yeast.

[brewinhard]

I started doing this but I let the started finish out before taking out the saved yeast. I decant, swirl, pitch the slurry and save a few ounces. That portion goes in a small, sterilized mason jar. I top it up with boiled, cooled leaving now head space. This is storing a mostly pure yeast slurry under clean water.

This yeast only sees a starter cycle and some osmotic stress from the water. I've built up a pitch after a month or two with no problem. It might just take an extra step to grow up enough cells. Viability is tough to predict so I mostly go off the volume of slurry. Not exact but I always over-pitch by eye and make sure the yeast is nice and active before pitching.

Bugeater posted a link to HBT with a thread on this. The directions and pics were straightforward and easy!

[anday6]

Bugeater posted a link to HBT with a thread on this. The directions and pics were straightforward and easy!

That's where I got the idea. Makes perfect sense since it doesn't beat up the yeast before being re-used.