What is hopbursting?

I must admit Matt that this is a method I have not heard of, until
doing a little research to help me with an answer. The cool thing about
homebrewing is that techniques often take on interesting names, and in
the case of “hopbursting” made my research a little easier. This is in
contrast to methods used by commercial brewers that frequently are used
generically. I think the reason for this is that commercial brewers
often develop methods that are viewed as “trade secrets” and as such are
not named.

Mitch Steele, Brewmaster of Stone Brewing, helped me out on this one by
digging around in the San Diego homebrew community and talking to Jamil
Zainasheff, who has used this method. Here is what Jamil explained about
it:

“Long ago I ran across a few commercial beers that were massively late
hopped and had little or no bittering charge. The aroma wasn’t anything
more than you would expect from dropping in massive amounts of hops near
the end of the boil, but the bittering had a “softer” character. It
seemed to me at the time that boiling hops for a longer time not only
resulted in more isomerized hop acids, but a harsher bittering the
longer you boiled them. By switching to a shorter boil and a greater
quantity of hops, you got a softer bittering and more hop character
because you tossed in lots of late hops.

“I tried this when homebrewing for an article for Zymurgy a while back,
and also had a number of other folks try the same thing. We used a
standard boil time (60 to 90 minutes), a very small or no early hop
addition (a few IBU at most), massive hopping the last 10 to zero
minutes, and then rapidly chill the entire wort with an immersion
chiller. Quick chilling of the entire wort retains more of the hop
character. Of course, you are limited to how many IBU you can get so a
really high IBU beer with this method is tough.

“In our initial commercial batches we tried this on a beer, adding
massive hops at the end of the boil. Unfortunately, the hot stand in the
whirlpool and during knockout was so long that we were getting 70 IBU
even with no other additions. We switched to pre-chilling our water and
also moved a lot of the hops over to dry hopping to get the IBUs down
into the 40–50 range. The only issue is that dry hopping doesn’t give
the same character as late kettle hops. In our new brew plant we’re
going to try a hopback to see if we can get more of that late addition
character instead.”

I was just at the Craft Brewers Conference in San Diego and picked up
some information related to the topic of new beers and brewing
techniques. You ask who uses a method like hopbursting and why. A talk I
listened to about Gen Y gives some insight into this general question.
We know about the origins of this particular technique, but what about
boundary pushing things in general? Many of these new methods are
developed by brewers who want to try something completely contrary to
conventional wisdom; apparently this is one of the traits of the Gen Y
crowd. The “why” originated as simply doing something different in the
kettle for a specific purpose, and this evolved into a method that
delivers an intense hoppiness that is different than adding hops early
in the boil for bitterness followed by aroma hops added late in the
boil.

On a very practical note, Mitch commented that it may be a good idea to
add a very small hop addition to the kettle when the boil begins, or
right before the boil, to help control foaming. This is indeed sound
advice since unhopped wort foams much more intensely than hopped wort.
Like the old Dippity Do adds, a little dab will do you. If you are
concerned about adding too much bitterness, select a low alpha variety
for this purpose.

Many of the hop bombs I sampled while in San Diego during the CBC had
hop intensities that defy normal brewing techniques. The Palate Wrecker
brewed by Green Flash Brewing is one example of a brew with very high
hop bitterness, coupled with aromas and flavors that I have never tasted
in a brew that was simply “highly hopped.” Some of these beers are
being brewed with unbelievably high hop charges approaching 1⁄10th pound
per gallon! I like to think the name hopburst may have been inspired by
Green (hop?) Flash (burst?). I imagine that some creative naming may
follow a tasting session of some of these monsters!

Being one of those brewers who likes to calculate things, large late
additions presents a conundrum in my math. One can assume that hops
boiled for 20–30 minutes have a utilization of somewhere around 15–20%,
but what about hops added 5–10 minutes before the end of the boil?
Depending on how long the hot wort is held to help settle hop solids the
utilization reports found in the literature vary from about 5–15%. This
makes it very difficult to “accurately” calculate late hop additions if
you want to hit a target bitterness level. I think most brewers who are
brewing these hoppy giants are more than likely relying on empirical
methods more than anything. If the last brew had 30 pounds (14 kg) of
hops dumped into a 10 BBL (310-L) batch and it turned out well, the next
batch may contain 33 pounds (15 kg) because a 10% increase “feels
right”.

I was still trying to wrap my mind around this “hopbursting” method when
I listened to a talk presented by Dr. Tom Shellhammer from Oregon State
University. Some of the data presented directly relates to this topic
and raised some interesting ideas. For starters, Tom discussed how the
“old school” IBU method, where iso-octane is used to extract iso-alpha
acids from beer, responds to more than simply iso-alpha acids. For
example, polyphenols and alpha acids from hops directly affect the
results of the IBU measurement. Many brewers assume that 1 IBU
corresponds to 1 mg/L of iso-alpha acids, and the data presented in Dr.
Shellhammer’s talk clearly showed that this is not correct. As it turns
out, the error becomes greater when huge late hop additions are made
since late additions increase the polyphenol content of wort and beer
more than early additions (polyphenols precipitate with proteins during
boiling) and late additions also increase the amount of alpha acids
present in wort and beer. Neither class of compounds significantly
contribute to beer bitterness, meaning that the increase in IBUs
measured using the iso-octane method is misleading.

I realize that I am drifting off topic, but this is interesting to me!
Tom reported that this error is not seen when a more specific method is
used to quantify iso-alpha acids in beer is used. The current standard
accepted by the American Society of Brewing Chemists (ASBC) and the
European Brewing Convention (EBC) is based on high performance liquid
chromatography (HPLC). The HPLC method accepted by both the ASBC and EBC
separates the constituents of beer using a chromatographic column and a
detector to quantify the concentrations of the various compounds that
are eluted from the column during the course of the run.

The interesting thing with all of this is that very few small breweries
have HPLCs in their labs and do not use this method for measuring IBUs
in beer. The iso-octane method, however, is pretty easy to perform if
you have a UV spectrophotometer. The punch line is that an IBU is not an
IBU . . . it depends on the method used in the lab. Most of you are
probably thinking, “what’s the big freaking deal, so what?” The big deal
is that IBUs have become a bragging right in the community of extreme
brewers. And based on the data I saw at the CBC I am thinking that some
of the claims of very high IBUs, some as high as 150, are due to errors
in the iso-octane method.

My point with all of this is that beers brewed by adding lots of hops
late in the boil do indeed have interesting and different hop
characters. But this method in general is a bit too new for much math to
be available to help the brewer when it comes to beer formulation. This
is one of those times when you need to rely on good notes,
experimentation, patience and persistence to end up with the type of
beer you seek. I saw an interesting show recently about the evolution of
the guitar during the 20th century. Things got pretty interesting when
the electric guitar was invented and then amped. Feedback was discovered
and this led to the development of all sorts of pedals. None of these
things could be put on paper with the musical notations used for
centuries by composers, but that did not stop musicians like Jimi
Hendrix from developing a whole new sound and style of guitar playing. I
think this hopbursting method may be the brewing equivalent of
feedback. As Wayne may have said, brew on, Garth!

Response by Ashton Lewis.