Is it possible to "re-train" lazy yeast? - Home Brew Forums
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Old 08-23-2012, 07:58 PM   #1
elgrindio
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Dec 2011
Loja, Ecuador
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Ok, so I understand why this doesn't come up much, since most can just go out and buy more yeast if something happens. Unfortunately, I can't because I live in Ecuador, S.A., and the only yeast I have (if I don't want to use bread yeast!) is the Safale -05 that my family sent me in the mail. I've been re-using it pretty successfully time after time(I pretty much brew every week). The only problem is that sometimes my OG was a little low, so I included enough table sugar to increase it by about .08-.10. I did this several times in a row, since most of what I read online indicated that it couldn't hurt anything, and in fact, the beer turned out fine. The problem is that I think I have caused it to become "lazy". When I tested FG before bottling last time, it was around 1.020. This was after 2 weeks of fermentation, and it wasn't that big of a beer to start with. Around 1.050-55. Normal should be around 1.012-14. Is it possible to toughen up my yeast after what I've done?

Thanks everybody!



 
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Old 08-23-2012, 09:48 PM   #2
eastoak
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Jan 2011
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i don't know about retraining but i would save the yeast in various containers and build up a starter each time rather than repitching the whole thing at once. i'd bet the FG problem is not related to the sugar but i could be wrong.



 
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Old 08-23-2012, 10:31 PM   #3
david_42
 
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You can do it by reversing the process, but it won't be easy or quick. Make a starter around 1.060 using only malt and put some of the yeast in it. Once it has fermented, repeat the process. Eventually, the yeast will lose its adaptation to the table sugar.
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Old 08-23-2012, 11:40 PM   #4
Denny
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I really have to question if it's the sugar that did it. Just constantly reusing the yeast could produce the same effect.
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Old 08-24-2012, 12:02 AM   #5
william_shakes_beer
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Next time you get a fresh strain of yeast, try harvesting a sample for storage BEFORE you pitch. The yeast will only see malt and will be "trained" to ferment maltose rather than dextrose. That way what you do with the trub does not affect the next batch.

 
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Old 08-24-2012, 12:41 AM   #6
SirJoshuaIV
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Mar 2012
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As someone else stated you can rebuild up the yeast culture by creating all malt starters. However, from my experience, when a yeast begins to mutate it is always better to just start over. I try not to go more than 5-6 generations on my saved yeast. I buy yeast once a year, and what I do is take all the trub from the bottom of the first ferment and "wash" it. I put it into 2-3 sanitized bottles and cap them and place them back in the fridge. I do this every time, and I have plenty of healty yeast to use all the time, By placing it in multiple containers that are labled, I know what yeasts have been highly used, and what yeasts should be discarded to prevent mutations.

If you truly have no way of getting any yeast shipped to you, you should definitely build up a starter with all malt, and do this several times, and you may be able to get it back to health.
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Old 08-24-2012, 01:24 AM   #7
Erroneous
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Also to help prevent the problem in the future, provided it is not mutation but adaptation to the sugar, add the sugar at the end of fermentation when the yeast aren't reproducing. That way they'll keep the maltose fermenting genes.

 
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Old 08-24-2012, 01:17 PM   #8
elgrindio
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Dec 2011
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Wow. You guys are great! Thanks for the help. I'll look into the suggestions.

 
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Old 08-24-2012, 03:17 PM   #9
DrHop
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He isn't really using that much sugar. What percent of the fermentables is the sugar? It's probably something unrelated to the sugar. Maybe mash temp or temperature or the yeast strain is old and maybe he has been unknowingly selecting for yeast that flocculate faster. I don't know how much I believe the whole saying that sucrose will train yeast and they will stop eating maltose. Maybe in extreme cases but they will be pretty hungry and there is plenty of maltose floating around.

I don't know if this would help but you could try to harvest yeast that don't floc as fast. Make a starter and wait for about half the yeast to crash out. Then make anther starter using the yeast that was in suspension and repeat this process a few times. Eventually I'd think you'd get a yeast that wouldn't floc as fast and would have higher attenuation. Has anybody tried this?

 
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Old 08-24-2012, 03:42 PM   #10
Denny
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Quote:
Originally Posted by DrHop View Post
He isn't really using that much sugar. What percent of the fermentables is the sugar? It's probably something unrelated to the sugar. Maybe mash temp or temperature or the yeast strain is old and maybe he has been unknowingly selecting for yeast that flocculate faster. I don't know how much I believe the whole saying that sucrose will train yeast and they will stop eating maltose. Maybe in extreme cases but they will be pretty hungry and there is plenty of maltose floating around.
This si what I was getting at. Why is everybody so hung up on blaming the sugar? There's not that much sugar on there. The problems the OP is having could very well be due to repeated repitching and have nothing at all to do with sugar.


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