ELI5: Liquid Yeast / Starter

[Bluejaye]

Please walk me through the process of using a liquid yeast pack. I've reviewed these 2 threads:

viewtopic.php?f=32&t=2152
viewtopic.php?f=32&t=2099

and this calculator:

http://yeastcalculator.com/

This will be my first time using liquid yeast. I normally re-hydrate my dry yeast, mostly out of habit from making breads, etc. than actual need, so I am comfortable doing that. I recently acquired a stir-plate and a flask, so I mostly want to play with these new toys. I also bought a Kolsch kit, which Kolsch yeast can only be found as a liquid apparently, so I want to make a starter to get that going, and then reserve a small bit of the yeast before pitching so I can make the kit again if I like it. This is what I *think* I should be doing, please correct me as needed. Thanks.

1. Smack the pack.
2. Put the content of the pack in the (sanitized) flask, fill up to 1L with ~3.5oz DME that has been rehydrated/boiled/cooled.
3. Stir away for about 24 hours before I brew
4. Reserve a tiny bit of the slurry for next time (baby food jar size or so), stored in the fridge, pitch the rest.

[mashani]

You don't really need to smack the pack if you are making a starter, although it will not hurt. As in smacking the pack will add nutrients which is a good thing, but you don't need to wait for it to swell up.

EDIT: I don't know about your flask, but I have a lab quality one, and a gas stove. So instead of sanitizing the flask, I simply put the DME/Water in the flask, and cover it with foil to a couple of inches down the flask. I boil the dme right in the flask for 15 minutes which sanitizes everything. I then let it air cool for a while then put it in cold water to cool to pitching temp. Then just pull the foil, pitch the yeast and put the foil back on. I don't use an airlock/stopper, the foil does the job.

EDIT EDIT: Do not do that if your flask of questionable origin, or if you have an electric stove.

[Bluejaye]

Thanks for the reply. That flask idea is interesting. Mine is from a laboratory supply company, Bomex glass, so I think I'll have to try it. It's suppose to be able to handle 932 degrees F, so 212 shouldn't be a challenge, I hope.

I had read that just the smack pack alone is questionable as far as enough food for the yeast to eat, so that's why I'm also doing a starter. Any comment on the starter itself (i.e. more or less DME)?

Any comment on reserving a bit for next time? I've found lots of articles about washing yeast post fermentation, but hadn't really seen anyone reserve any pre-pitch. All of my cooking experience with yogurt, sourdough, etc. I reserve a bit for the next batch, so I am kind of wondering why brewers don't. I guess I'll find out how bad of an idea it is, if no one has ever done it before. Seems to me it would be a lot easier than the washing technique if it turns out to be viable.

[mashani]

Do remember that the 212 is the water inside, not the flame/contact outside. But if you have lab quality glass made for use on a burner, then your gas stove is not going to harm it. Hopefully. Always be careful and smart. IE for example the glass will be *freaking hot* after 15 minutes on your stove - do not touch it with bare hands. Do not bash it around. Do not put it onto a cold surface immediately. Yes that all sounds stupid, but well, some folks don't think right, or have never worked with lab equipment. Basically just turn off the heat and walk awy for a while, nothing bad will happen by ignoring it for a half our or so before you actively cool it to pitching temp.

I use 3oz DME per liter.

RE: saving it nothing wrong with it, you just have to be more sanitary then most bread bakers or yogurt makers are. Although the principle is the same, sour dough is one thing, beer you don't want sour dough, unless you are trying to make a sour. You can't really make a starter that will make beer that will make you sick just like it's really difficult to make yogurt that will make you sick - for the same reasons, ph changes and fermentation process being bad for pathogenic bugs - but you can make one that will produce sour beer pretty easily if you are not careful.

So, I will sometimes make a 2L starter when I only need 1L to pitch, and then put the other half in sterile (as in boiled as if I was canning for real) canning jar(s), and use them as I wish later.

You can also wash the yeast right out of your fermenter, which is a similar process - there are tutorials on how to do this posted on here somewhere search for yeast washing.

There is a limit to how many generations you can do this without getting mutated yeast. Whether the mutation makes better beer or not is the question. I'd suggest as a general rule of thumb not to go past 5 generations or so, unless you like to experiment.

There are ways to try to revive a weirded out mutated strain, but it's generally not worth the effort for us.