ok, so me, the long time crusader for the potential of k-97 has some results.
started an imp stout
1.082og, 84 IBU
15% by weight DME for gravity boost
1lb RB, 300g black malt
2 packs of k97 added 29 days ago.
chilled to ~60 for pitch, brought up to a ~66-68F ambient room for 7 days, massive ~5 inch krausen, once it died down and it seemed like no activity i brought it to a ~57-60F ambient room for the rest of the time. this yeast has always had the stupid temp suggestion on it of "12-25C" aka 54F to 77F
this yeast does not work properly at low temps or works extremely slowly.
after a month its down to 1.029 (64%) attenuation. yes its an imp stout, but the specialty grains are at 11% of total. i was expecting minimum 71-72%, ideally the 77% i believe fermentis estimates.
were the yeast packets old? (because no one wants k97?)
did i prematurely bring the temp down, ending the fermentation?
does the yeast just suck at attenuating or is greatly mislabeled like many fermentis dry yeast packages?
taste-wise, it is actually really good, so i am going to salvage it. the bitterness feels bracing even for 84 IBU. strong and decently nuanced roasted malt taste, chewy but frankly not as chewy as id expect for 1.029, clean, but the intense flavours may be hiding the much feared "breadiness" (not dismissing it, i just havent had a finished example to analyze fully yet). it is not excessively hazy/yeasty either with no gelatin added yet.
i secondaried it, adding a packet of WLP001 i had sitting around and i will give it another 2 weeks.
In short: i find the taste of the beer this yeast produces agreeable, but its fermentation characteristics are crap. would not recommend this for p much anything when there are so many alternatives.