Hops: Its History and Its Use
By Jim Layton
Various herbs and spices have been added to beer
to improve its flavor throughout history. Hops were first used in
continental Europe, where it was noted that they helped preserve the
beer as well as provided a pleasant bitterness. Hops were introduced
to England during the 14th century. Nowadays, hops are an essential
ingredient in almost every sort of beer.
The hops used in brewing are actually the flower of the hop vine.
The hop flowers are stripped from the vines, then dried to prevent
decay. Hops are commonly available to home brewers in three forms:
whole, pellet, and plug. Each form has some advantages and disadvantages,
and each form can be used to make excellent beer. Here is my take
on the subject:
Whole hops (you may hear them referred to as "whole leaf" or "whole
flower") are simply loose dried hop flowers. High quality whole hops
cannot be surpassed for flavor and aroma. They can be easily removed
from the wort by straining. Their physical structure, being something
like a small, soft pinecone, allows them to form a filter bed that
can be used to trap hot break particles after the boil. On the other
hand, they don't store as well as the other forms, so getting and
keeping high quality whole hops can be a bit difficult. They also
behave like a sponge and absorb sweet wort, which may result in a
significant loss if you are doing concentrated, partial volume boils.
Pellet hops are made by first grinding whole hops into a powder. Heat
and pressure are applied and the powder is extruded through a perforated
plate. In use, pellets immediately return to the powdered state and
disperse when put into the boil. Pellets, because they have less exposed
surface area, stay fresh much longer than whole hops. They also take
up less storage volume. These advantages have led to wide use of pellet
hops by commercial breweries, both large and small. On the down side,
some of the more volatile aroma oils are thought to be lost during
the pelletization process. Separation from the wort can be a problem,
as the tiny particles tend to pack together and clog any screen fine
enough to catch them. One method to deal with this is to do like the
big boys do: give the kettle a strong stir to create a whirlpool.
Cover the kettle and leave it alone for 15-20 minutes. The hot break
and hop particles will collect in a heap in the center. Drain the
wort from the side of the kettle using either a valve or a siphon.
Try to get the liquid stuff out and leave the solid stuff behind.
Don't worry if some of the hop and break particles get past, its no
big deal. Another technique is to use a cloth bag to contain the pellets
during the boil. I've used both methods numerous times and they both
Plug hops are really just whole hops in a fancy package. They have
been pressed into ½ ounce tablets but will quickly resume their original
form in boiling wort. Use them exactly as you would whole hops.
Boil time has a great effect on the amount of bittering, flavor, and
aroma that hops impart to the beer. As the boiling period increases,
hop bitterness goes up while hop flavor and aroma decrease. Hops boiled
in excess of 45 minutes are commonly called bittering additions. Boil
times from 15 to 30 minutes provide less bitterness but more flavor,
hence these are sometimes referred to as flavor hops. Aroma hops are
boiled 10 minutes or less. These are just generalities, of course.
Bittering hops will provide some flavor and aroma, aroma hops will
provide some bittering and flavor.
The alpha acid rating measures how much bittering material the hops
contain. Everything else being equal, hops with a rating of 8% will
provide twice as much bitterness as an equal amount of hops with a
rating of 4%. The alpha acid content of hops depends on breeding (genetics)
and culture (factors such as climate, soil fertility, amount of rainfall
or irrigation). The alpha acid rating of hops will vary from year
to year and farm to farm. The concept of Homebrew Bittering Units,
or HBUs (sometimes called AAUs), was developed to help homebrewers
compensate for this variation. Simply put, HBUs equal the alpha acid
content multiplied by the weight. To calculate the ounces of a certain
hop needed to equal a given HBU number, you divide the HBU number
by the hops alpha acid rating. For example, suppose the recipe says
to add 4 HBUs of Cascades. Your Cascade hops may be rated at 6.6%
alpha acid. To determine how much of the Cascades to use, 4 / 6.6
= 0.6 ounces.
Beer bitterness is measured in International Bittering Units, or IBUs.
Many beer recipes note the IBU content of the finished beer. The ability
to predict how many IBUs your beer will contain is a powerful tool
when trying to nail a style, clone a commercial beer, or just tweak
a recipe. The exact amount of bitterness extracted from the hops depends
on the boil time, boil volume, specific gravity of the wort, hop alpha
acid content, the amount of hops, whether the hops are loose in the
boil or in a bag, and whether the hops are whole or pelletized. With
all of these factors involved, you can see how predicting the IBUs
in your homebrew can be fairly complicated. Fear not, other folks
have developed hop utilization tables and equations that make the
calculations fairly simple. Norm Pyle's Hops FAQ at http://realbeer.com/hops/FAQ.html
has the most complete treatment of this subject that I have seen.
Highly recommended reading.
Dry hopping is the practice of adding hops directly to the fermenter.
The purpose of dry hopping is to add a strong hop aroma to the beer,
though some hop flavor also results. The quantity of hops used for
dry hopping 5 gallons may vary from ½ ounce up to 2 ounces. The proper
way to do this is to wait until the fermentation activity has nearly
ended, otherwise the escaping CO2 will carry most of the hop aromatics
away. Leave the hops in the beer for a week or two before bottling.
I prefer whole or plug hops for dry hopping, as the larger pieces
are easier to separate from the beer. I find that placing a large
nylon grain bag, sanitized by boiling for 10-15 minutes, over the
racking cane works well to keep the hop bits back when racking to
the bottling bucket. You can also dry hop in the keg if you bag the
hops, otherwise the pickup tube may clog. Many brewers worry that
adding hops to the green beer will result in an infection. Forget
it, it just doesn't happen.
Heat, light, and oxygen are the enemies of hop freshness, so store
your hops somewhere cold, dark, and airtight. The best container is
an oxygen-barrier bag, either vacuum sealed or purged with inert gas.
A glass jar with a tight lid, such as a mason jar, is good. Plastic
sandwich bags are lousy. The freezer is the coldest place in your
house, so that's where hops belong when you aren't using them. Great
beer requires fresh hops (OK, lambic excepted).
Hop varieties can be confusing. I offer these general groupings and
recommendations as a way to make some sense of it all. If the particular
variety called for in a recipe is not available, one of the other
hops in that group will provide a reasonable substitute. This list
is far from complete but it contains a fair number of the more popular
types. The style suggestions are my personal preferences, you are
free to develop your own.
American "C" hops (Cascade, Columbus, Chinook, Centennial) have distinctive
flavor and aroma that many describe as citrus-like. They are widely
used in American-style ales. Some commercial examples which feature
the "C" hops are Sierra Nevada Pale Ale, Red Seal Pale Ale, Anchor
Liberty Ale, and Bigfoot Barleywine. I highly recommend these hops
for American pale ales, American amber ales, and American IPAs. They
are not, in my opinion, appropriate in English ales, Belgian ales,
German ales, or any lager beer.
English Ale hops (Kent Goldings, Fuggles, Challenger, Target, Styrian
Goldings, Willamete) are not necessarily grown in England but they
provide the hop flavor and aroma associated with English ales. Recommended
for English pale ale, bitters, porters, stouts, English IPAs, and
brown ales. Also recommended for Belgian ales.
Lager hops (Tettnanger, Hallertauer, Saaz, Spalt, Liberty, Mt. Hood,
Crystal, Tradition) are recommended for lager beer, of course, but
also in German ales. Many American ale recipes use a bit of these
in addition to the "C" hops for added flavor and aroma complexity.
Also recommended for Belgian ales.
General purpose bittering hops (Nugget, Cluster, Magnum, Perle, Galena,
Northern Brewer) are commonly thought to have poor aroma and flavor,
so are normally used only in early kettle additions. As an exception
to this rule, Anchor Brewing uses only U.S. Northern Brewer hops for
bittering, flavor, and aroma in their famous Anchor Steam. The rough
and earthy flavor of Northern Brewer adds a distinctive character
to this beer.