Beer Forum

What are the IBU and ABV that folks find as the limit for repitching. Say for example if you make a beer w/ 20 IBU, are the alpha-acids starting to hinder yeast budding without de-bittering? And is pitching a cake from a 6% ABV beer too much? Where are these limits? Are there any other factors (besides number of generations, cleanliness and mutation from high temp ferms)?

I feel like I've heard them over and over again on the sunday and jamil shows and seen them in these forums and just can't for the life of me come up with the sources at the moment.

Thanks!
Snafui

I wouldn't do it but I've read post of brewers repitching yeast from beers 6% ABV and higher.
Anything over 5% ABV is toxic to the yeast so it's best to repitch from beers at or below 5% ABV. I'm not sure of the IBU's affect on the yeast. 20 IBU's isn't much. I usually repitch from a Blonde Ale or a Munich Helles which isn't very hoppy.

I recently repitched some German Bock Lager yeast (WLP 833) from a Maibock (6.7% ABV, 29 IBU) into another Maibock (6.6% ABV, 36 IBU). Both beers are delicious and my untrained palette can not detect any off flavors. I started with a huge starter for the first batch then rinsed the yeast a few times with some of my wife's Heineken for the second batch.