Liquid yeast past use by date.

[zgoda]

...That's why I prefer Wyeast to wlp, the packages can be as old as 18 months and still be viable IF you dare to make starters.

Not arguing, but how is there logically a difference? Are you just saying Wyeast has a higher cell-count to begin with?

That's what I observe but I don't think it's related to initial cell count, which is higher in WLP, that's what I've been told. WLP vials lose viability quickier than Wyeast smack packs. 18 months after packaging you can be sure there are still some live cells in smack pack, but this is not the case for WLP vial, had some 10 months old that did not took off in starter at all. Zymoferm vials keep viability for even shorter. I guess this is related to packaging, not yeast itself. Perhaps some UV issue?

[brian_beer]

Very interesting, thanks for the update.

So I guess I am partly saved by my poor efficiencies at the moment - getting closer to 20L on most brews. Once I sort my mash issues and start getting full volume I guess it might make more difference though.

What effect does the lower rate have on the brew though? I thought that wort is good for yeast and it will multiply in there anyway so does the starter somehow just allow that to happen faster/better?

I've added the mrmalty link to my favourites. Will check it out before next brewday.

So if I'm adding a lambic smackpack to secondary....same size starter needed? (This is for the beer in http://www.jimsbeerkit.com/forum/viewto ... =2&t=53260)

Thanks guys

[Wolfy]

...That's why I prefer Wyeast to wlp, the packages can be as old as 18 months and still be viable IF you dare to make starters.

That's what I observe but I don't think it's related to initial cell count, which is higher in WLP, that's what I've been told. WLP vials lose viability quickier than Wyeast smack packs. 18 months after packaging you can be sure there are still some live cells in smack pack, but this is not the case for WLP vial, had some 10 months old that did not took off in starter at all. Zymoferm vials keep viability for even shorter. I guess this is related to packaging, not yeast itself. Perhaps some UV issue?

Do you smack the Wyeast packs before trying to revive the yeast from such old packs?

I'm just wondering if the fact that Wyeast has the in-built nutrient pack (in a sterile environment) that it allows you to 'revive' the yeast before the pack is open.
With such long storage times, there are likely only a very very small number of cells alive, so while it may be that pre-smack there are the same number of cells live cells as in in a WhiteLabs vial, the Wyeast smack-packaging provides more viable cells once the pack is smacked and opened (because those few living yeast will be able to reproduce and revive some due to the smacking process). But the other vials without the in-built reviving nutrients are such that the viability is so low as to be impossible to revive.

[zgoda]

I always smack the nutrient packet and wait until fully swell. In 4-5 days the package swells like a balloon. Well, usually. Then healthy starter, at least 1.5 litre for ales, 3.5 litre for lagers.

As I am constantly tight on cash, the only liquid yeast I'm buying is from such bargains.