Beginner - yeast cultivation question

[nixhaz]

Hullo!
I'm going to start cultivating yeast, got my stir plate and equipment ready, however I have no DME as I brew all grain. Can I use sugar plus yeast nutrient instead or is this a terrible idea? Just with all this lockdown business I don't want to go ordering unnecessary stuff.

 

[An Ankoù]

Yes you can. Go easy on the nutrient.
Next time you make an AG brew of about OG 1040-1050, keep a litre or so, unfermented in the fridge. When you're ready to cultivate some yeast. put half a litre in your flask, brink it to the boil, cap it with tinfoil, let it cool and Bob's your uncle.

 

[nixhaz]

thanks @An Ankoù !

 

[An Ankoù]

thanks @An Ankoù !

See edit, too.

 

[jackthehat]

I think that I read somewhere that once yeast adapts to sugar it can be reluctant to switch back to maltose. I don't know how true that is, though.

The last time I propagated some yeast (from SN 1698) I did a mini-mash in a teapot and used that. It worked fine.

 

[nixhaz]

Perfect thankyou @An Ankoù mate! I was going to do that, just wanted to get my one last precious packet of S-05 on the go before next brewday!

 

[nixhaz]

@jackthehat that is a brilliant idea! Thanks!

 

[An Ankoù]

Perfect thankyou @An Ankoù mate! I was going to do that, just wanted to get my one last precious packet of S-05 on the go before next brewday!

There's no need to culture dried yeast, in fact it's not a very good idea. A packet will deal with 25 litres easily. I would rehydrate it, but not "grow it up". Put 150 ml lukewarm water in your flask (boiled and cooled water) about 30C. Sprinkle the yeast on top and leave for 10 minutes. Agitate the flask gently to make the yeast mix with the water. Leave 15 minutes and then pitch.

 

[strange-steve]

Can I use sugar plus yeast nutrient instead or is this a terrible idea?

This is an interesting question actually, and as is often the case with brewing, it may not be all that straightforward. The general consensus is that you shouldn't use an all sucrose starter. It supossedly results in little cell growth and low attenuating yeast. What may help is using a quality nutrient, not just DAP but something containing yeast extract like servomyces.

However, many of the dry yeast manufacturers apparently grow the yeast with a molasses solution but in a very specific drip-feed fashion which is very important. Also molasses contains more nutrients than table sugar does.

Another however, many people have used an all sugar starter with good results so who the hell knows. It might be one of those things that is in itself "bad practice" but that you might "get away with" if everything else is good.

 

[nixhaz]

Thanks guys, I want to cultivate it because it is my last packet and I am not sure when I will be able to get more!

 

[foxbat]

Braukaiser covered this here. Basically without any malt content there was no yeast growth, even with diammonium phosphate nutrient added:

Pure sugar solution, even with the added nitrogen, did not yield any significant growth which is likely due to other nutrients (vitamins, trace elements) that are found in wort.

 

[nixhaz]

Great thanks, I'll do a mini mash in my thermos flask I think!

 

[Brew_DD2]

I think you'd be better harvesting the yeast after brewing rather than trying to create a starter with sugar.

 

[An Ankoù]

I think you'd be better harvesting the yeast after brewing rather than trying to create a starter with sugar.

Me too. But in the old days. I used to culture yeasts from bottled beers with sugar and I can assure you it worked. I Don't do it now of course.

Great thanks, I'll do a mini mash in my thermos flask I think!

This would be preferable as it may be that some yeasts adapt differently to the way they're cultured (having read the comments above). But I don't get why it's so important to expand this last packet of yeast in this way. If you rehydrate and pitch as I suggested earlier, you can then harvest the yeast within 24-48 hours from the top of your beer. Then at the end of the fermentation you can harvest again from the bottom of the fermenter. And every bottle you finally end up with have a sample in the dregs that you can culture up from.

 

[Drunkula]

http://brulosophy.com/2015/06/05/real-wort-vs-dextrose-yeast-starter-exbeeriment-results/
I've done it. Don't do it unless you want to use it to make sugar wash and have nutrient. It absolutely stinks if you don't use nutrient. The stress makes really bad egg smell.

In the brewlosophy experiment the starter with dextrose took 5 days to ferment out, then there was a 96 hour lag in the actual beer (do not want!) and it took over 3 weeks to brew out the beer. Do not want!

I make starters from dried yeast and I think MyQul does, too. My last beer used 1.5g of yeast in a 1 litre starter for a dark wheat and it brewed out in no time and tastes great. This time I used the last 1.020 of runnings from the mash and ran it overnight as it was no-chilling. I've also got a ludicrous amout of dry malt extract so for me DME is actually cheaper than yeast by a long way. A litre costs 7p.

 

[nixhaz]

I'm a total noob to all this, I just assumed that it was better to culture it rather than to harvest it (I need to do more research obvs!). I guess I thought maybe less chance of infection doing it that way rather than harvesting.

 

[Drunkula]

A lot of people overbuild starters so you've got extra yeast left over after you pitch to make another starter and it's pretty easy to control the hygiene doing that.

 

[AXW123]

I've got quite a few packets of yeast spare if you want some.

 

[MyQul]

For my 10L brews I make a real wort starter using 200g grain to make a 1L starter. Althought ths ends up as about 600ml as I no chill it in a big jar then decant the wort off the trub. I just use a 3L pot which I put into the oven at 65C to mash for 15 minutes. Do a dunk sparge and then do a two minute boil to sanitise. I then add 1g of dried yeast. In this way I can make a pack of yeast last 10 or so brews

 

[nixhaz]

Thanks guys! @Drunkula that's what I was intending to do, I'd forgotten the word (overbuild).
@AXW123 That's great, what yeast do you have for sale?
@MyQul that's really useful info, thanks. For a 23L batch would you just leave it for longer before pitching do you think? I have to read up on pitching rates and suchlike.
Yeah, I was looking for DME and it was nearly £10 for just 500g delivered!