A Question for Yeast Farmers

Adeptus Titanicus

I'm planning on doing a few small "experimental" brews, about 5 litres each, but as I have only wyeast slap packs which are for up to 25 litres, I really don't want to be wasting any, as I assume it wouldn't be good to throw the full pack into such a small brew. As I've never cultured yeast, I'm wondering if any of you more experienced brewers have kept cultures from the likes of wyeast packs going for any lengh of time?

In fact, I'm not even sure if such a small brew will be effective, so I'm open to advice on the following:

• Is a 5 litre brew feasible (as in, will the smallish volume have any bad effects)?
• Should I only use 1/5 of the wyeast slap pack in such a small brew (basically, can you add too much yeast)?
• If I only use part of the culture, can I keep the rest alive for any reasonable length of time using simple methods?

Thanks Braumeisters

A

noby

This is what you need to do:
Make up a small batch (1/2 gallon or so ) of wort with either extract or grain. Boil for at least ten minutes. Some people add a little hop to it. When it's cooled, pour it into a 1 gallon demijohn, and pitch your yeast (which you've smacked the day before). Let this ferment out. When it's done, give it a good shake to get all the yeast into suspension. Pour it through a sanatised funnel into 6 or so brown bottles. Cap and refridgerate. Now you have 6 batches of yeast from 1. These can be used for your normal 5 gallon brew, but would also be fine for 1 gallon. They keep in the fridge from anything from 2 to 6 months, depending on who you believe. Take one out the day before, and make up a starter with it.

You could then take one of these bottles, and follow the same procedure to get another generation of yeast. I never went this step as I thought 6 from 1 was good enough value.

As for the 5 litre brew, I don't see any problem with it.

guildofevil

^ What he said ^

There are other techniques, involving slants of wort/gelatin mix, etc. but Noby's technique is the simplest one to do and I would go with that. Very cost effective too.

You can also use yeast skimmed from the top of the primary to ferment a new beer, or just pitch wort directly onto the yeast cake of the last beer you did. I have done this before with great success.

I once pitched a high gravity wort onto the yeast cake of a bitter I had done and it just went nuts! A couple of hours after I had pitched it, the krausen had pushed the lid off the bucket and was flowing down the sides.

bigears

pitch your yeast (which you've smacked the day before).

One thing to bear in mind with Wyeast - depending on how old the yeast is you may need to leave it longer than a day for the package to swell. A lot of the packs we get over here are older than is the case in the US. I have read previoulsy that you should leave one day per month after packaging (the packaging date should be on the pouch - if not it is normally 6 months before the 'best before'). If you are making a starter as above this is not nearly as important but if you're pitching direct make sure that you've given the pouch enough time to swell up sufficiently. If the yeast is past it's best before date or if you're brewing a high gravity beer a starter is essential.

They keep in the fridge from anything from 2 to 6 months, depending on who you believe.

You see such a wide variety of views on this - some people say they only last a few weeks - in this case splitting the yeast into 6 would be a waste of time. I'm inclined to believe they will last a lot longer - what's the longest you've left them and still found them viable?

oblivious

I have been told that after about 3-4 generations of reusing the same yeast cake, the "original" flavors become revitalized. I don’t know how true this is but it maybe its worth a shot.

Adeptus Titanicus

Thanks guys, that's really good advice. For such a small brew the yeast would have been the biggest proportion of the cost, so stretching it to 6 from 1 would be great

I plan on doing the small brews this weekend, so I probably won't get the chance to let the 1/2 gallon starter ferment out in time. Or how long would you leave it? I guess I could make a starter tonight, pitch a portion of it on Sunday into the brew and then use the rest to create 5 bottles of yeast to use later?

bigears

If you make the starter tonight you'll be ready to pitch on Sunday. As you said you can pitch some and split the rest into the bottles.

noby

what's the longest you've left them and still found them viable?

Not sure. Probably 3-4 months. If your starter doesn't take off, or seems a bit dodgy, then it's probably best to chuck it and use some dry yeast.

Adeptus Titanicus

Fantastic Thanks all.

Oh, should the bottles storing the yeast starters be sealed or airlocked? Or wait till they've settled then seal? So many questions eh?

noby

Once your original starter has fermented completely, you can cap your bottles and stick them in the fridge.

oblivious

That’s a very nice method noby

Adeptus Titanicus

I think I'll be needing a bigger fridge.

Could be the start of a yeast exchange. Might be something worth thinking about, in terms of spreading the love

noby

I can't take all the credit. It's just the method I've used in the past.

guildofevil

Adeptus Titanicus wrote:

Could be the start of a yeast exchange. Might be something worth thinking about, in terms of spreading the love

Now that IS an idea.

bigears

Opens up great possibilities for scapegoating: "yeah, my beer turned out crap because yer man's yeast was rubbish"

I have a couple of out of date liquid yeasts that I haven't got around to using yet. Wyeast 3068 (Weissbier) and White Labs 002 (English Ale). I'll be making a starter with these and I'll be happy to share a couple of bottles for anyone who wants them. It will probably be the New Year before I get to them though.

Adeptus Titanicus

That worked a treat guys, thanks. I didn't make up a full set of 6 bottles, but I wish I did now (I was skimping on bottles as I only have a limited number of swing-top bottles at the moment). I have two Wyeast 1028 London Ale in the fridge now, and a third one went into a test 5 litre brew yesterday evening. Man did the fermentation kick in fast!

We may do another test brew in the next week or two, so if we're using a different yeast I'll do a full set of 6 and spread the love if anyone is interested.

bigears

Glad to hear it went well, it's good to know the theory works

guildofevil

Oops. Posted in the wrong thread.

Kirin Iciban

A glycerin solution can be used to freeze yeast for long term storage in the freezer. From Papazians book it suggests a percentage of yeast per volume of glyercin, cant remember now.

You can pick up glycerin in the boots chemist on Henry street, though I dont know if this is 100% pure or not.

Definitely worth a shot for those expensive Wyests smackpacks, saving a little yeast before you pitch/prepare starter

oblivious

I think we use 10% final conc in the lab

Adeptus Titanicus

Kirin Iciban wrote:

A glycerin solution can be used to freeze yeast for long term storage in the freezer.

Interesting idea. Would certainly take up less room than bottles in the fridge, or what volumes are you talking about for a glycerin solution? I assume it'd just be the yeast slurry suspended in the glycerin solution?

Anyone tried this?

oblivious

I use a 10% (1 teaspoon to 9 of yeast slurry) solution of glycerol for freezing cells, although the cells are frozen a -80c. Maybe increase to 20% or so for a home freezer (-20c). The glycerol helps prevent the ice crystals for destroying the yeast cell wall.

Yea just mix the yeast with the glycerol and put in the freezer.

Adeptus Titanicus

Bloody hell! -80C is industrial strength I vote you to be the yeast banker!

oblivious

I work in a lab, but you should be able to do it at with a home freezer