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rivetcatcher
Joined: 21 Apr 2016 Posts: 132 Location: Thailand
Drinking: Way Out Wheat - Mindcircus
Working on: Zombie Dust
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Link Posted: Thu Oct 11, 2018 2:14 am Post subject: Yeast starter from frozen yeast |
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I’m in the process of defrosting some liquid yeast that I have harvested from a starter and frozen with glycerin. This is something I will write up in another post with my results.
My question is this, the process I am following recommends defrosting the Yeast and putting it into a small 500ml starter to get it going. The resultant yeast should then be transferred to a larger 2 litre starter to continue growing.
I am struggling to understand why they have two steps. Why don’t I just pitch the defrosted sample straight into the larger 2 litre starter. The gravity of the two starters will be the same anyway. To me it seems an unnecessary step as once the yeast gets going surely it should continue working through a 2litre starter the same way that it would through a 500ml.
Am I missing something?
Rivet
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Ozarks Mountain Brew
Joined: 22 May 2013 Posts: 737 Location: The Ozark Mountains of Missouri
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Link Posted: Thu Oct 11, 2018 4:03 am Post subject: |
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the reason is to not to stress the yeast, a dormant yeast seeing a huge amount of food could freak out or stress and produce off flavors in the process, it's better to go slow and test the yeast first
_________________ "Imagination is more important than knowledge. Knowledge is limited. Imagination encircles the world."
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rivetcatcher
Joined: 21 Apr 2016 Posts: 132 Location: Thailand
Drinking: Way Out Wheat - Mindcircus
Working on: Zombie Dust
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Link Posted: Thu Oct 11, 2018 8:01 am Post subject: |
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Yeah I understand that in regards to a full batch of beer but when we are talking about a starter with a difference in wort volume of between 500ml and 2000ml I’m not 100% sure that the yeast would really be underpitched.
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dp Brewing Company
Joined: 08 Jul 2013 Posts: 664 Location: Midwest
Drinking: Chocolate Taco, Raspberry Mango Cider, American X, Sandy Dunes
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Link Posted: Thu Oct 11, 2018 2:48 pm Post subject: |
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2000 ml is 300% larger than 500 ml. Seems like a bid difference to me. I would set it up personally.
_________________ Visit dp Brewing Company
Hangovers hurt....but good memories last forever!
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rivetcatcher
Joined: 21 Apr 2016 Posts: 132 Location: Thailand
Drinking: Way Out Wheat - Mindcircus
Working on: Zombie Dust
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Link Posted: Fri Oct 12, 2018 9:03 am Post subject: |
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I’m in the process of testing one of my frozen viles. Defrosting and starting with a 500ml starter.
Rivet
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McGruber
Joined: 12 Aug 2014 Posts: 237 Location: Idaho
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Link Posted: Thu Oct 18, 2018 3:48 pm Post subject: |
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People with PHD's in Yeasties say that you're not supposed to propagate yeast by more than 10X at each step. So if you start with 1 mL of yeast, you're supposed to bump it up to 10 mL, then 100 mL, then 1000 mL, and so forth. I believe that it simply has to do with what has been observed by those who spend all their time studying such things to be the most efficient and healthiest way to propagate yeast. It's the standard for professional brewers/ breweries.
I don't see what volume of yeast you're starting with - if you have 200 mL of yeast, then a 2000 mL starter makes plenty of sense.
Of course you can add a smaller volume of yeast to a bigger volume of wort - one smack pack into 5 gallons is way bigger than a 10X increase. However, as Ozarks Mountain Brew states, the potential is that yeast could produce off flavors, they could not like the ratio of wort components compared to their ability to consume them and lyse (explode - creating off flavors and lower than expected attenuation because cells are dead), they could just hang around and simply work minimally, and/or from a cost perspective it would simply be a waste of wort. I'm sure you'd be fine in either case, but I agree that "theoretically" there's a big difference between pitching (for example) 1 mL of yeast into 500 mL vs 2000 mL of wort from a ratio perspective.
Good luck!
P.S. I'm curious how your experiment goes. I've always heard you shouldn't freeze yeast.
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rivetcatcher
Joined: 21 Apr 2016 Posts: 132 Location: Thailand
Drinking: Way Out Wheat - Mindcircus
Working on: Zombie Dust
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Link Posted: Fri Oct 26, 2018 2:36 pm Post subject: |
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I ended up starting with a 250ml starter, let that ferment out and then added it to a 2000ml starter.
The yeast fermented well with no off flavours at all.
The funny thing was that the yeast fermented a hell of a lot more vigourously than the original yeast out of the smack pack. I can only put it down to the volume and freshness of the yeast that was revived from frozen.
I’m really happy with the results and will definitely be freezing yeast in the future. The process is very easy and ony requires a few extra bits of kit. I have around 14 vials of Wyeast 1318 and 10 vials of 1968.... they should last years. The money you spend on kit will save you a fortune in yeast and allow you to have yeasts of your choice on hand whenever you need them.
I have a few pics etc of the process and I can document it in another post if anybody is interested.
Rivet
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