10% Viability

[sama]

Have a tube of white labs that mr malty tells me is 10% viable.would an initial 500ml starter before stepping to 2000ml be the go for a 1045 ale?!

 

[raven19]

That sounds like a reasonable option, however theoretically a whole vial is good for a 23L ish batch. 10% surely is ok for then 2.3L ish. So you could go straight to the 2L starter.

If nervous about it, go the smaller 500ml first then step up to 2L.

10% seems pretty low, is it still sealed in the vial and been in the fridge the whole time? yeast type? manufacture date?

 

[Wolfy]

Assuming a single batch volume of 23L, a 2L stir-plate starter is about the ideal size.
Since your vial is old, stepping up rather than pitching directly into 2L should in theory give you better yeast health and more growth, so it's something that I'd do.

 

[Fourstar]

100ml to 1L would probably suffice.

 

[sama]

Assuming a single batch volume of 23L, a 2L stir-plate starter is about the ideal size.
Since your vial is old, stepping up rather than pitching directly into 2L should in theory give you better yeast health and more growth, so it's something that I'd do.

i never pitch vials without starters,regardless of age.have allways used mr malty pitching calc.it has never failed me yet,but have never had a vial a month past best b4.to me 10% viable vial is akin to reculturing 2 stubbies worth of cpa,and i allways step up for that,tho my rinsed yeasts that usually end up say 15ml in volume go straight into a 2litre starter tho there usually only 2 weeks in age from harvest till they go into a starter,this grows me 80 to 100ml of yeast.the 500ml step up aint a hassle so im gonna go with it for peace of mind.thanks guys

 

[pdilley]

2 litres is fine. I don't have the free time with a near 4 hour daily commute so I do straight 2 litres and no steps to recover yeasts with success. I have photos but no post yet of the 3 year old Scottish Ale yeast I pitched 4 days ago into the fermenter and did a 2 year past expired date White Labs vial that went 3 month unrefrigerated in warehouse storage and a fresh split Wyeast 1968 all with the same method. Stir Plate, 2 litre of standard or 1/2 strength wort, and the optimum temperature I've found to be 25C. Old yeasts can lag for a few days to a week but I've revived them all. So don't worry you'll likely do great with your attempt.

Cheers,
Brewer Pete

 

[DUANNE]

looking at this id be stepping it up personally.

 

[sama]

did you even read the posts :huh:

 

[mckenry]

Just thought I'd show you all what Mr. Malty and yeastcalc claim as 0% (zero, not a typo) viability. Smacked this yesterday afternoon. This is this morning. Ive had correspondence with Kai about this and there is no answer. Its 4 months since manufacture date, but clearly alive and well.

 

[goatchop41]

Just thought I'd show you all what Mr. Malty and yeastcalc claim as 0% (zero, not a typo) viability. Smacked this yesterday afternoon. This is this morning. Ive had correspondence with Kai about this and there is no answer. Its 4 months since manufacture date, but clearly alive and well.

image1 (2).jpg

Try the Hombrewdad yeast calculator - I've had good success with it (admittedly, I've only done 2 liquid yeast batches so far though). Apparently it's a bit more accurate than the Mr Malty one, it tells you exactly how big each step needs to be, and you can adjust more variables yourself (eg. starter wort strength, overbuilding the starter, etc.)

 

[Kono]

Just thought I'd show you all what Mr. Malty and yeastcalc claim as 0% (zero, not a typo) viability. Smacked this yesterday afternoon. This is this morning. Ive had correspondence with Kai about this and there is no answer. Its 4 months since manufacture date, but clearly alive and well.

image1 (2).jpg

Whack a sample under a microscope and do a viability test, that's the only way to check viability. What you have there is a swollen packet.

I agree, its not 0% but that doesn't mean that as a general guide it won't be somewhat accurate to replicate the kind of pitch you SHOULD have for the ferment flavour profile the calcs aim for.

It's a lot more complicated than a date = viability.

I'd be keen to see how viable that packet actually was though!

And after 4 months it should still be viable, not great, but they do state on the packet they are good for 6 months..

 

[seamad]

Just used some 1968 that was over 2 years old. I split packs into 4 vials and keep in the fridge. Use the little bag of wort in the smack packs for the first step to bring it back to life, then another 3 steps to build up required numbers ( bit of guess work involved as to first step numbers ) Use http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/
Always a good idea to taste a starter made with old yeast to make sure it's OK ( but oxidised )