EVALUATING HOPS
Aroma of Raw Hops
 Examine appearance (color, moisture)
 Rub lightly, smell
 Crush and release aromas, smell
Hop Aroma in Beer
Hop oils are the main contributors of hop
flavor and aroma
Researches have identified more than 400
aroma compounds
 Oxidation of hop oils, and
biotransformation caused by yeast
make contributions of individual
compounds harder to measure
 Chemistry that creates aroma is not
clearly understood
 Science of Hop aroma is constantly
evolving
HISTORY OF HOPS
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Hops were introduced to beer making prior to 1000
A.D.
Prior to the widespread acceptance of hops, various
bitter herbs, seasonings, and spices were used to
balance the malt sweetness. called gruit.
Any number of herbs and spices went into gruit
including henbane, wild rosemary, heather, ginger,
spruce, juniper, and bog myrtle.
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First recorded use of hops used to bitter and preserve
beer around 1150
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Hops came into widespread usage in 16th century with
passage of the Reinheitsgetbot (1516)
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In 1710 the English parliament banned the use of
non-hop bittering agents, at least in part to prevent
brewers from evading the new penny-per-pound hop
tax.
HOP STRUCTURE
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Brewers Hops are the cone like flower of the
Humulus Lupulus bine.
Hops are a perennial plant of the cannabaceae
family
The essential ingredients are located in the
lupulin glands, located at the base of the
bracteoles
The lupulin resin contains alpha acids and
essential oils that contribute the characteristic
bitterness, flavor, and aroma that are
associated with hops in beer.
The amount of alpha acid is usually expressed
as a weight percent, and is determined by
laboratory analysis.
MYRCENE, HUMULENE,
CARYOPHYLLENE, FARNSENE. The four
major components of the essential oils and
between them they account for about 60-80%
of the essential oil of most varieties.
Myrcene contributes a “green hop aroma” and
is often found in many dry-hopped beers. It
has an odor which is described as “herbaceous,
resinous, green, balsamic, fresh hops
GROWING HOPS
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Daylight hours majorly impacts
harvest yield.
Majority of hop production occurs
between 35 and 55 degrees latitude
During peak growing season they
grow very
rapidly, up to twenty inches per
week. Commercial hop growers
cultivate hop bines on V-shaped,
wire and twine trellises that are up
to twenty feet tall.
The cones are placed in a kiln
where 140° air is circulated, drying
the cones to about 30% of their
green weight.
After cooling the cones are
compressed into bales or further
processed into pellets or extracts.
Hop producing country
HOP PRODUCTION
2011 Pounds
produced
Germany
82,672,500
United States
64,991,608
China
29,282,560
Czech Republic
13,778,750
Poland
4,409,200
Slovenia
4,850,120
United Kingdom
3,350,992
Australia
2,3.1,602
Important production centers
 Hallertau in Germany
 Yakima valley
(Washington)
 Willamette valley (Oregon)
 Western Canyon County
Idaho
 Kent in UK
HOP FORMS AND PRODUCTS
Hops are available to brewers in whole-leaf, pellet,
or extract form. Each of these forms has
advantages and disadvantages.
Fresh or Wet Hops – Fresh hops are green,
unprocessed cones, often added to the beer within
hours of harvest. Wet hops give beers an intense,
bright hop flavor and aroma.
Whole-leaf Hops – Whole-leaf hops are simply the
dried hop cones that have been compressed into
bales. They are believed to have greater aromatic
qualities than the other forms . and are easier to
strain from wort.
Pellets – To make pellet hops the dried cones are
shredded, compressed, and extruded into pellets or
plugs. The shredding process exposes the lupulin
glands and removes a percentage of the vegetative
matter.
Extract – For hop extracts, the alpha acids and
essential oils are pulled from the cones using heat
and various solvents. These concentrated liquid
extracts can be used in the brewing process just
like hops. There are separate extracts for bittering,
flavor, and aroma.
HOP VARIETIES & CLASSIFICATIONS
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Hops can be generally divided into two broad
categories, bittering and aroma. Some are
considered to be "dual-purpose”
Those hop varieties that contain high levels of
alpha acids are called bittering hops because a
lower volume is needed to achieve high levels of
bitterness.
Those with lower alpha acid content but higher
levels of essential oils are called aroma hops.
Beyond this broad division, general
characterizations can be made based on the
traditional area of origin.
Noble varieties include Saaz, Spalt, Tettnanger,
and Hallertauer Mittelfrueh
Continental hops = European
New world hops = American & Southern
hemisphere
Propriety hops
Falconers' Fight & Zythos Hops by Hopunion
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Hop varieties are often associated with particular beer
styles; in fact, some styles are virtually defined by
their hop character.
Continental styles, particularly the more hop-oriented
ones, are also often associated with more local
Continental hop varieties.
American styles, especially such hoppy examples as
American pale ale and American brown ale, benefit
greatly from the floral, citrusy character of the
dominant American varieties such as Cascades,
Centennial, Columbus or Chinook.
It is important to note that the region of cultivation is
as important as the hop variety in determining the
character of the crop.
Classic European hop varieties grown under a
different climate in the United States exhibit different
characteristics than the same varieties grown on
European soil.
HOPS IN THE BREWING PROCESS
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Hops also contribute many
secondary attributes to beer: they
provide a measure of bacteriological
stability, aid in kettle coagulation,
and contribute to a stable head.
Bitterness arises from the alpha
acids, which consist of humulone,
cohumulone, and adhumulone; the
proportions of each will vary
according to hop variety.
They are isomerized into iso-alpha
acids in a vigorous boil, rendering
them much more soluble in the
wort, in addition to increasing their
bitterness.
The essential oils, which contribute
to flavor and aroma of the finished
beer, consist of dozens of
compounds.
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International Bittering Unit, or
IBU is a measure of the
concentration of isomerized alpha
acids present in the finished beer,
and is expressed in milligrams per
liter.
Utilization normally tops out at
about 30 %
Some additional factors which affect
the utilization rate are boiling
temperature, whether or not hop
bags are used, and filtration losses.
A different utilization is typically
assumed for each hop addition
(when multiple additions are used);
in this manner, the IBU
contribution for each hop addition
may be estimated, then totaled.
It should be noted that the only way
to determine the IBU level in the
finished beer is through a direct
measurement in the laboratory.
HOP ADDITIONS
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Kettle Hops – Kettle hops is the name given to those
hops added to the kettle during the boil. These include
early addition hops for bitterness and late addition
hops for flavor and aroma.
Bittering Hops – Bitterness from hops comes from
alpha acids found in the lupulin glands of the hop
flowers. The main alpha acids are humulone and
cohumulone and adhumulone. In order to become
bitter these acids must be chemically altered,
isomerized, by boiling.
Flavor Hops – Hop flavor and aroma are derived from
essential oils found in the lupulin glands. These oils
include humulene, myrcene, geraniol, and limonene,
among others. The flavors are released as these oils
become dissolved into the wort during the boil. Flavor
hops are added with twenty to forty minutes remaining
in the boil.
Aroma Hops – Because the aromatic essential oils are
highly volatile, aroma hops are added in the last
minutes of the boil to minimize their loss to
evaporation.
Dry Hopping – Perhaps the most common non-boil use
of hops is dry hopping. In this process hops are added
to beer in the conditioning tank after fermentation is
complete. The hops are left in the beer for a week or
two allowing the essential oils to dissolve. Dry hopping
provides a very bright and fresh hop aroma with slight
enhancement of flavor.
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Hop Back – Another process for increasing hop aroma
is to use a hop back. A hop back is a small tank that is
placed between the kettle and the chiller in a brewing
system. The hop back is filled with hops and the hot
wort is run through it on the way to the chiller.
First Wort Hopping – First wort hopping is a pre-boil
addition of hops to the hot wort as it runs into the
kettle from the mash/lauter tun. This is said to give a
smoother hop aroma and flavor without significantly
increasing bitterness.
Mash Hopping – Mash hopping is the addition of hops
in the mash tun.
Randall – Randall is a plastic filter housing that is
filled with hops and inserted in the draft line coming
from the keg. As the beer passes through the Randall
on its way to the tap faucet, the alcohol dissolves the
essential oils providing a fresh burst of hop character
OFF FLAVORS
Light struck
 Aroma= rubbery, skunky
 Appropriateness = never
but consumers have
come to tolerate the
flavor, often associating
it with imported beer
Formed by a reaction of
isohumulones to blue light.
Beer packaged in clear or
green glass are more
vulnerable
Advanced hop products are
sometimes used in clear
bottled beer.
Isovaleric acid
 Aroma = stinky cheese
 Appropriateness =
never
Caused by the formation
of organic acids during
the improper storage of
hops.
Can also be caused by
a Brettanomyces infection
FURTHER READING, REFERENCES &
RESOURCES
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http://www.barthhaasgroup.com/en/
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http://www.bjcp.org/study.php
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https://cicerone.org/content/certified-beer-server
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http://www.aperfectpint.net/Hops.pdf
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http://beersensoryscience.wordpress.com
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Tasting Beer: An Insider's Guide to the World's
Greatest Drink - Randy Mosher
For The Love of Hops: The Practical Guide to Aroma,
Bitterness and the Culture of Hops – Stan Hieronymus
How to Brew: Everything You Need To Know To Brew
Beer Right The First Time – John Palmer
Designing Great Beers: The Ultimate Guide to Brewing
Classic Beer Styles – Ray Daniels