Each beer received the same significant hop dose for 90 minutes and
for 30 minutes. Breweries then followed one of four procedures: 1) added
one pound of Amarillo (8.4% alpha) per barrel at the end of the boil,
with 50 minutes of post-boil residence; 2) added one pound of Amarillo
per barrel at end of boil, 80 minutes post-boil residence; 3) added one-
half pound of Amarillo per barrel at the end of boil, with 80 minutes
post-boil residence, and one-half pound of Amarillo per barrel as dry
hops; 4) dry hopped with one pound of Amarillo per barrel, with no
additional kettle addition.
A sensory panel that included 34 experienced tasters later evaluated
the beers based on seven characteristics: perceived bitterness,
intensity of hop aroma, intensity of hop flavor, malt character, citrus
notes, fruity notes, and grassy-vegetal notes. In assessing the results
Havig cautioned that these were intensely hoppy beers and that Amarillo
is a very distinctive hop. Nonetheless, the results were statistically
significant and resulted in several conclusions:
- Longer post-boil residence (procedure 2) resulted in more hop
flavor, aroma, and perceived bitterness than shorter. This
supported the initial hypothesis. "This is in contrast to a
commonly voiced opinion among craft brewers that volatile hop
oils are quickly driven out of hot wort, and therefore, wort
cooling should happen as quickly as possible after the addition
of final hops at or near the end of the boil to preserve the hop
flavor and aroma in the wort," Havig wrote.
- Longer post-boil residence resulted in more hop flavor than
dry hopping, and that hop flavor is best developed in the
kettle.
- There was no apparent relationship between measured bitterness
and hop flavor or hop aroma, but significant correlations
between perceived bitterness and hop flavor or hop aroma. Havig
wrote, "This result also brought into question the usefulness of
using IBU as a method of measuring the hop character of very
hoppy, IPA-style beers."
- A combination of late hopping and dry hopping (procedure 3)
resulted in greater hop aroma than longer late hopping. However,
it appeared there was a diminishing return for additional
quantities used in dry hopping.