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Badly Stored Dry Yeast And Yeast Starter

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cam89brewer

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I am looking at making a nice German lager and have all the ingredients but yeast and cant justify making an order from Grain and Grape at the moment.
The local HBS is pretty much just an open shed and has all their yeast sitting out in the open and wouldn't be surprised if it is the same stuff that was there over summer,if I was to buy say some s-23 and used a starter first would it create many off flavours or if it starts off should I be right?
 

Wolfy

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From what you've said I don't think I'd trust their yeast at all.
However some cells should still be alive, so making a starter - even a stepped starter - would be a good idea.
However, you really should make a 4-5L starter for a standard sized batch of average gravity lager.
 

cam89brewer

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From what you've said I don't think I'd trust their yeast at all.
However some cells should still be alive, so making a starter - even a stepped starter - would be a good idea.
However, you really should make a 4-5L starter for a standard sized batch of average gravity lager.
So if I did get the starter going and made it up to 4-5L and was healthy would I get a different result than if I added a starter which used well stored yeast? or is the only risk the chance of there being no live cells left in the sachet?
 

Wolfy

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So if I did get the starter going and made it up to 4-5L and was healthy would I get a different result than if I added a starter which used well stored yeast? or is the only risk the chance of there being no live cells left in the sachet?
I'm not sure exactly what you are asking, but will try to provide an answer anyway, but please realize this is all guesswork based on the fact we don't really know how bad condition the yeast is, but it's possibly safe to assume the worst.

The ideal solution (when using dry yeast) is simply to pitch the 'correct' amount of dry yeast (after rehydrating if you think you should).
If the dry yeast had been stored well (kept refrigerated and was not too old) you should be able make a good enough estimated-guess at how many live cells you will be pitching. However, since you've said the yeast is not kept cold and not treated well, there is not really any way to even guess at how many live cells might be there (at room temp dry yeast will lose about 20% of its live cells each year, at refrigerated temps it will only lose about 4%).

Generally when making lagers, you want to keep the yeast-character to a minimum, so underpitching or pitching stressed or unhealthy yeast is not a good idea - so directly pitching the dry yeast would be a risk - it might turn out well (you could pitch an extra pack or two and it might work out fine) but if the yeast is crappy your beer might turn out crap.

For 22L of 1.045 OG Lager beer, most conservative yeast pitching estimators would suggest about 350-400billion cells, then assuming a resonable inoculation rate, resonable yeast-health, decent nutrients and aeration (stir-plate) that equates to a starter about 4L in size. That was a guess based on lots of assumptions (which may or may not be correct in your case), in addition dry yeast is essentially force-fed all the nutrients it needs to start a healthy fermentation when it's pitched and so if you pitched the 'correct' amount of healthy and viable well kept and refrigerated dry yeast into an inadequate starter (either too small, not enough nutrients or oxygen) it's possible that you might do more harm to the yeast's health than you would do good.

So it's a risk either way, do you guess at how many yeast cells are alive in packs, and maybe even pitch an extra packet or two to compensate, or do you assume the worst and make a starter which if the yeast was in top shape might not have been a good idea. If you have the equipment and ingredients to make a good large starter, that might be the recommended option, but if you don't you might just want to guess at how many yeast packs it's best to use.
 

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