Just found & read this. Thought it is applicable here.
http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34093/Wolfe_thesis.pdf?sequence=1
(first page is blank)
It's waay too long to read the whole thing, but there's a
great summary of hop compounds affecting aroma/flavour on pg4-16, plus some stuff right at the end in the Conclusion (plus some other tidbits in the Discussions).
In particular reference to this, page 16 talks about the
polyphenols in the hops. They're water soluble, so easily extracted (think compounds in tea leaves); but contribute both
positive & negative elements to taste/aroma. They seem to be the
main contributors to harshness & astringency (aside from poorly balanced IBU's, i assume!).
I think it's implied in the experimental results that for dry hopping, pellets achieve the best extraction however everything is extracted, including the polyphenols. So flowers/plugs might be the better dry hopping material to reduce potential harshness (?). Also, i think the less processed material has a better yield of geraniol (floral & ester aromas ?).
So it may come down to the variance of amounts & types of polyphenols in a given hop in a given year as to how harsh it'll be. Since i don't think this info is reported by producers, i guess we're back to anecdotal evidence as to what's harsh or not (further complicated by individual variance in detecting different polyphenol compounds).
Haha ... so maybe i added nothing to the discussion really.
Nothing to see here. Carry on
