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This question was just asked by a good mate of mine on another forum...

- how comes after racking to 2ndary you run the risk of yeast autolosys if left for too long?
Yet, you can harvest the very same yeast into a bottle with some beer and store for a starter for the next batch and not get yeast autolosys??

Also, the very same beer is transferred to a bottle and then primed, this in turn gets the yeast active again, and it multiplies, this then supposes that there is some oxygen that has entered the beer at bottling stage. This bottle is then stored for a period of time - hopefully longer than a couple of weeks at room temp and the bottled beer does not get affected with yeast autolosys??

..Just a thought..
Dr Chris White of White Labs told a group of Adelaide brewers that to get autolysis you need a lot of yeast and a lot of heat. A secondary stored in a fridge should therefore not be in any danger of autolysis

Jovial Monk
Like so many home brewing questions, the answer is, "It depends".

I have tasted an ale beer that stayed in primary for 3 months, abused with poor temperature control, then was kegged and showed no sign of autolysis. This is definitely not good beer handling practice.

Autolysis probably depends on what yeast is being used, length of time, amount of yeast, temperature and many other factors.

If you want to find out about what yeast autolysis smells like, harvest some yeast slurry and store it in a jar for a few weeks or months. Even when stored in a fridge, I have often smelled strong autolysis in stored slurry.
The only time I have observed any negative effects is when I left a not-quite totally cleaned fermenter under the house because I had to catch my flight to the US. When I got back it was absolutely rank! It did take 3 weeks at probably 25C+ to stink. I left a secondary in the fridge for the same period of time and have observed no ill effects, probably one of my top IPA's. So, I would say that for a few weeks in a refrigerated environment, you shouldn't have to worry about autolysis. Especially if there is a slow fermentation still going on, since autolysis depends on the yeast "starving" and becoming cannibals. After a big fermentation the yeast energy reserves should be high and their metabolism will slow at low temps.

Or else I just like the flavor of autolyzed yeast :eek:
- how comes after racking to 2ndary you run the risk of yeast autolosys if left for too long?

Racking to secondary reduces the risk of autolysis. As the Monk said, you need a lot of yeast for it to be a problem. By racking to secondary, you take the beer off the yeast cake in primary, hence less yeast.
Changing track slightly here....

When should you rack to secondary - I always thought you racked just as the kauzen starts to die back, but the brewers @ Grumpys said to only rack once primary ferment is complete??...
The Grumpys used to recommend racking at half gravity. I think most people rack when primary is complete to avoid stuck ferments.

Do a search, there's heaps of threads on here about racking.

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