How to save/recover out of date yeast

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How to save/recover out of date yeast

Postby wedwards » Sun May 11, 2014 10:04 pm

Coming from an all grain brewing background of making up starters for my beer and doing calculations on yeast viability and pitching rates, I was alarmed when I started distilling and most people didnt seem to care for this practice. In fact, using bakers yeast, its pretty much unnecessary.

However, my last batch of whiskey using safspirit malt got an infection in it either because the yeast was no longer viable, or the yeast was not viable enough to keep any infections at bay. My standard processes were followed and Ive never experienced this before.

Given that I dont get to enjoy my hobby as much as I would like to, things like yeast, grain, hops, etc can sit around for a while before I get to use them. In this instance, the safspirit malt had a best before date of September 2012 - thats right, 18 months past its ok date.

I recently had a situation where I was making some beer (my standard pilsner) and found that my yeast was approx 12 months past its use by date - this was white labs vial of german lager yeast from memory. I ended up making a starter and putting the yeast on my DIY stirplate for 48 hours - at the end of this, I had a very active bunch of yeasties ready to go into my beer, and it has turned out to be one of the best pilsners I have ever brewed.

Back to my problem with the safspirit malt. I figured why not give the same process a try - cant hurt before I determine that the yeast is crap and throw it in the rubbish right?

So I made up my standard starter of 2 litres of water and 200gm of pale malt extract, let it cool down to around 25 degrees and dumped about 4 dessert spoons of yeast into it. Put it on the stir plate out in my garage for forgot about it for 2 days. When I came to check, it was going like crazy, and I had a nice healthy dose of condensation all around the top of my starter flask.

Moral of the story, dont throw out yeast unless you have tried this or want to throw cash down the drain.

To make a starter, I use a ratio of 100gm of pale malt extract for every 1 litre of water. Heat the water on its own on the stovetop until it gets warm and then stir in the malt extract so that it dissolves, bring to boil for 10 mins then I put it straight into my chest freezer for a couple hours to cool down. When its at desired yeast pitching temp, put your yeast in, give it a shake, and then put on stir plate. Dont cover the top of your starter vessel with glad wrap, just use aluminium foil, as you want some air to be able to get in/out.

The stir plate will cause your yeast to come to life much quicker than just leaving them sit in the starter, as its always moving and adding oxygen, which yeast will thrive on. Stats everywhere say this is a much faster way to multiply your yeast, and I have found that to be correct.

Anyway, thought I would share this with everyone as I have seen and heard of others throwing out old yeast that they though was dead, and Im not not convinced that is necessary at all with a little know how and effort.

If anyone wants a link to the site where I got ideas for making my stir plate, just let me know - its very simple and you need minimal tools, just a fan from a computer power supply, a rare earth magnet out of an old harddisk, and an old mobile phone charger, as well as a basic potentiometer from jaycar. You can easily find plastic coated stir bars on ebay or at any decent homebrew shop.

Hope this helps someone.
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Re: How to save/recover out of date yeast

Postby wedwards » Sun May 11, 2014 10:09 pm

I should add that I did a test of using the same amount of the same yeast, out of the same packet, in the same sized starter, without using the stirplate and after 4 days it was still clinically dead - as far as I can tell based on my single experiment, the stir plate is what made all the difference.
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Re: How to save/recover out of date yeast

Postby MacStill » Sun May 11, 2014 10:15 pm

So you're saying a little stimulation and a night in the house is better than sitting in the shed doing nothing with a beer :wtf: :think: :wtf:

:))
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Re: How to save/recover out of date yeast

Postby SBB » Sun May 11, 2014 10:15 pm

wedwards wrote:Coming from an all grain brewing background of making up starters for my beer and doing calculations on yeast viability and pitching rates, I was alarmed when I started distilling and most people didnt seem to care for this practice.

Laughing my arse off here :laughing-rolling: :laughing-rolling: , I think we cause a a lot of alarm to a lot of the beer brewers who turn up here.
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Re: How to save/recover out of date yeast

Postby wedwards » Sun May 11, 2014 10:19 pm

MacStill wrote:So you're saying a little stimulation and a night in the house is better than sitting in the shed doing nothing with a beer :wtf: :think: :wtf:

:))


Thats right! The yeast can have the stimulation and I will have the beer in the shed :)
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Re: How to save/recover out of date yeast

Postby MacStill » Sun May 11, 2014 10:29 pm

you had me worried for a minute :laughing-rolling:

nice post tho mate, I've got a 500gm unopened block that's about a year past best, so if I have any dramas I know what to do now.

thanks :handgestures-thumbupleft:
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Re: How to save/recover out of date yeast

Postby crow » Mon May 12, 2014 3:30 am

Yes I bought some yeast awhile ago only to find it was years out of date, 2009 or something. Anyway I found providing you use a starter it will be ok. Sure only a percentage of the yeast is viable and each yr that will slowly reduce but a starter solution will get enough of it to increase to a usable amount for pitching :handgestures-thumbupleft:
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