Using Sucrose As Yeast Growth Medium

[Krmak]

I'm in a dillema... I have quite a few yeast tubes that I want to freeze for my yeast bank, but the problem is that a lot of them are gushing out and foaming when opened.
So I've decided that I'll pour these tubes into a erlenmayer flask with 1 l of 1,038 OG starter to minimize te problem with foaming and to increase the cell count, and then chill the starter, decant the wort and continue the regular procedure for filling my vials with glycerine/water/yeast .
The one problem I have is that I'm running low on DME. This got me thinking if I could substitute the DME for sucrose (table sugar)?
I know that's not recomended for making starters for beer, but in this case I'll be freezing the yeast and when I'll need them for a brew I'll revive them in a DME or normal wort starter....

cheers :icon_chickcheers:

 

[fcmcg]

Um... No bloke..
I'm on the iPhone but if you do a search there is quite a few threads by some very experienced yeast people...
Wolfy has written several excellent articles ,with pictures ..
Seek and she shall find the answers !
Cheers
Ferg

 

[pbrosnan]

I'm in a dillema... I have quite a few yeast tubes that I want to freeze for my yeast bank

I've probably got this wrong but from the above it looks like you're going to freeze the yeast which would destroy it so you wouldn't be doing that.

 

[Krmak]

I've probably got this wrong but from the above it looks like you're going to freeze the yeast which would destroy it so you wouldn't be doing that.

no, no as I said I'll store the yeast in a water/glycerine/yeast mixture so the glycerine should prevent freezing. I'll just put them in the freezer so they are at -20 degrees. I expressed myself a bit akward

The prime concern for me is how will the yeast, primary cultured on sucrose, react (after they have been put into the freezer and stored for months) when put in a DME starter for the beer itself. I suppose they will have some lag time before they get adjusted to maltose and the more complex sugars in the DME? But then they should normally multiply right?


:icon_cheers:

 

[Thirsty Boy]

not so well - its far from the best thing you can do for yeast health and viability. your yeast wont be in great shape, then you want to freeze it and then you expect it to grow and then to ferment.... not the giving it a fair shot really are you? You say you are running low on DME.. thats OK, just get them into a little bit of proper wort to reculture. You only need a teeny tiny bit to grow enough yeast to freeze. a 1L starter is enough yeast for dozens and dozens of tubes.

1 of your tubes into 100ml of wort will give you enough yeast for a few tubes - that keeps your yeast preserved until you buy some more DME and can upscale however much you like.

TB

 

[Wolfy]

It's best to handle the yeast as infrequently as possible - so what if the tubes gush a bit when you open them (can't imagine it will do much harm).
I'd simply transfer them directly into your freezing-mix and store them without any extra fuss.

However, don't expect great results (if you have not frozen yeast a few times before) you might find that some vials do not even survive - so if your vials are anywhere-near-new I'd keep them as long as possible in the fridge before messing around with other stuff.

 

[Thirsty Boy]

ahh - wasn't thinking "whitelabs" vials, I was thinking that we were talking about small freezing vials that had already been frozen and were up fo re-culture.

Hell yeah, what wolfy said. Take a suck of yeast from the vial (foamy or not) with a sterile pipette - shove that on to freeze in a tube or two - then make a starter and brew a beer with the rest of it.

 

[DJ_L3ThAL]

Reviving an old thread due to a similarity in my Q. I recently when to pitch some harvested slurry (was quite a few ~6 months old) and was lazy as I forgot to build a starter in advance for the brew day. The reagent 500mL bottle I had ~200mL slurry stored in gushed like made when I opened it up. I did turf it and used a fresh pack of US-05 to be safe.

Reading Wolfy's comment above, does gushing of a stored yeast slurry not indicate something wrong has occurred? I did smell the reagent bottle and it did smell slightly different to the same yeast slurry stored in smaller vials (the vials smelt like clean yeast, the reagent bottle had a "champagney" smell to it, best description I have). I've obviously gone down the cautious road and all is well, but I'm just wanting to inform myself if this occurs again in the future, so does gushing of a yeast sample not necessarily mean it's bad providing the sample still smells like it should?

Also while I have whoever is reading, is darkening of the colouration over time of slurry in the fridge normal?

 

[Yob]

as yeast stary to die, they turn a peanut brown sort of colour, yep, perfectly normal.

Gushing is no real indicator of vitality or health

 

[GalBrew]

All gushing means is that your sealed slurry has fermented out what it can and is under pressure from the CO2 it produced. This can happen with White Labs vials also.

 

[DJ_L3ThAL]

Thanks Yob and Gal. Noted