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I am considering making some yeast slants to try to start a little bit of a yeast bank. In my research i have read about folks making a starter from the yeast in the bottom of a bottle conditioned beer, then inoculating the slants from that. I have also read about washing the yeast cake, but cant seem to find if there is another step between washing the yeast and inoculating slants. Is it better to just wait and use the yeast in the bottom of the bottles, or use the washed yeast cake.

It seems to me that the yeast in the carboy might be a healthier sample having not been in the alcohol as long, but there would also be a lot more unwanted material. If this is the best route, is it necessary to harvest from a starter from the washed yeast, or can i inoculate the slants straight from the washed yeast, or do i need to wash it at all.

The yeast in the bottles would be cleaner, but might have more mutations etc.

Thanks

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2 Answers

Seeing how you'd be scaling up quite a bit from a slant to a solid starter culture, I am not sure it would really matter whether you take it from a bottle or from a primary yeast cake.

Personally, I think the better idea is to streak out a plate first. Reason being is because if you pick up some bacteria or other microbe from the carboy/bottle, you'll be able to see it as a different colony on the plate. Then you can pick a pure colony to drag out on a slant. Where you might just get a mixed culture on the slant.

In response to the OP's edits: You don't need to wash the yeast prior to grabbing some for innoculation. But again, its best to be doing a streak on a plate, then pick a colony for a slant. Slants are really for storage. Prior to storing a pure colony, you have some culture work to do. Streaking on a plate helps to be sure you don't have any bacteria because you'll seperate it out into single cells. Those single cells grow into individual colonies. Also, the yeast you are grabbing from the carboy will also have some hop resins stuck to the cell walls. Streaking to a single colony will help "dilute" that out as one cell grows into several cells. Thereby you streak onto a slant cells with much reduced hop resins. Washing would be a waste of time when you have the equipment to do streaking and colony picking.

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I'd use the yeast from the fermentor, as it's going to be the healthiest yeast. Make sure your fermentation is complete first, so you get a good cross-section of early and late flocculators. The yeast in the bottles will largely consist of the least flocculant cells.

Of course, if you're just saving yeast from beer that you're brewing, you could make slants directly off your wyeast pack or white labs vial, as well. Or pull some top-crop from your starter vessel.

Brew Strong has done several shows which are germaine to this.

Also, if you're wanting to get samples from commercial beers that are bottle conditioned, remember that many breweries use a different yeast for the primary fermentation than the one they use for conditioning.

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