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jayhoz · 05-24-2007, 03:03 PM

Will re-using yeast from a previous brew that developed an off flavor result in a brew with an off flavor as well?

I recently brewed a heffe that I am not happy with due to off flavors (see recipe section for details). I collected the yeast cake and plan on using this for a future heffe. Is this a bad idea? Are the yeast more likely to produce these off flavors now?

homebrewer_99 · 05-24-2007, 03:56 PM

What was the off flavor?

jayhoz · 05-24-2007, 05:44 PM

Quote:

Originally Posted by homebrewer_99

What was the off flavor?

http://www.homebrewtalk.com/f12/advice-hefe-recipe-28129/

**the_bird** · 05-24-2007, 05:51 PM

Reading that thread again, you've got a pretty high number of IBUs for a hefe; more typical would be 10-15 IBUs, not ~25. If you're comparing your hefe to commercial ones and judging yours to be too harsh, that's probably why.

With that said, if you have any concern at all that the batch was infected, toss the yeast and buy fresh. From what I have heard (Jamil), the hefe yeast strains tend to not hold up as well to long-term storage as others, anyway. If you think the problem was that you used too many hops (you used more than twice what I used in my hefe), that it was NOT an infection, and that you'll be re-using the yeast within a reasonable period of time, then yeah, I'd keep it.

jayhoz · 05-24-2007, 05:54 PM

Quote:

Originally Posted by the_bird

Reading that thread again, you've got a pretty high number of IBUs for a hefe; more typical would be 10-15 IBUs, not ~25. If you're comparing your hefe to commercial ones and judging yours to be too harsh, that's probably why.

With that said, if you have any concern at all that the batch was infected, toss the yeast and buy fresh. From what I have heard (Jamil), the hefe yeast strains tend to not hold up as well to long-term storage as others, anyway. If you think the problem was that you used too many hops (you used more than twice what I used in my hefe), that it was NOT an infection, and that you'll be re-using the yeast within a reasonable period of time, then yeah, I'd keep it.

Thanks for the feedback. I actually dropped the IBU's down to 18 for the brew.

homebrewer_99 · 05-24-2007, 08:27 PM

That's a hell of a lot of hops for 7 lbs.

I only use 3% AA for (60 mins) for 6 lbs of malt.

jayhoz · 05-25-2007, 01:43 PM

I've updated the recipe in that thread. I used 1oz at 60mins and 0.25oz at 20mins.

Anyone have any thoughts on whether or not yeast get trained / spoiled once they have been in a brew that produced off flavors?

ebeer · 05-25-2007, 03:27 PM

I think this question would be best answered by a yeast authority (try emailing White Labs or Wyeast, I've found them to be very helpful).

With that, here's my take as a non authority (which is to say my experience with yeast comes from brewing and reading - not years of lab research). I don't think a healthy, early generation yeast will become reprogrammed. Yeast do mutate over generations, which is why you should only go 5-10 generations then go back to your 1st generation source or buy new. If you make a yeast starter to ensure a strong healthy population of yeast they should ferment reliably and predictably. Off flavors would most often be the result of some external variable (unstable fermentation temps, high or low fermentation temps, exposure to light, infection, etc.) Control the variables and healthy yeast should do their job predictably, even if they came from a previous batch with off flavors.