I have four questions regarding yeast derived phenols that I hope someone can shed some light on.
1. Does anyone know of any studies (published or unpublished) showing that stressing yeast fermentation via lack of oxygen, low pitching rate, or high gravity can cause phenolic off-flavors in beers fermented with POF- yeast? As far as I can tell, phenolic production is only tied to one or two genes, and yeast that have that gene will produce significant amounts of phenolics, while others will not. I know that genetic drift could maybe cause this, but outside of that can POF- be made to produce phenols?
2. Same question above, but for POF+ yeast. Does stress create more phenols?
3. Does anyone know of an extensive list of POF+/- yeasts from White Labs or Wyeast, including non-Belgian strains?
4. How many English Ale strains are POF+? I've heard claims that some English Ale strains are POF+, but I can't find direct evidence for that.
Thanks,
Dan
1. Does anyone know of any studies (published or unpublished) showing that stressing yeast fermentation via lack of oxygen, low pitching rate, or high gravity can cause phenolic off-flavors in beers fermented with POF- yeast? As far as I can tell, phenolic production is only tied to one or two genes, and yeast that have that gene will produce significant amounts of phenolics, while others will not. I know that genetic drift could maybe cause this, but outside of that can POF- be made to produce phenols?
2. Same question above, but for POF+ yeast. Does stress create more phenols?
3. Does anyone know of an extensive list of POF+/- yeasts from White Labs or Wyeast, including non-Belgian strains?
4. How many English Ale strains are POF+? I've heard claims that some English Ale strains are POF+, but I can't find direct evidence for that.
Thanks,
Dan
