EVALUATING HOPS

Aroma of Raw HopsExamine appearance (color, moisture)Rub lightly, smellCrush and release aromas, smellHop Aroma in BeerHop oils are the main contributors of hop flavor and aromaResearches have identified more than 400 aroma compoundsOxidation of hop oils, and biotransformation caused by yeast make contributions of individual compounds harder to measureChemistry that creates aroma is not clearly understoodScience of Hop aroma is constantly evolving

HISTORY OF HOPS

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.

First recorded use of hops used to bitter and preserve beer around 1150

Hops came into widespread usage in 16th century with passage of the Reinheitsgetbot (1516)

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 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 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 PRODUCTION

Hop producing country

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

 Australia2,3.1,602

Important production centers Hallertau in Germany Yakima valley (Washington)

Willamette valley (Oregon) Western Canyon County

Idaho Kent in UK

HOP FORMS AND PRODUCTSHops 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 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

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 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.

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

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.

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 struckAroma= rubbery, skunkyAppropriateness = never but consumers have come to tolerate the flavor, often associating it with imported beerFormed 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 acidAroma = stinky cheeseAppropriateness = neverCaused by the formation of organic acids during the improper storage of hops.

Can also be caused by a Brettanomyces infection

FURTHER READING, REFERENCES & RESOURCES

http://www.barthhaasgroup.com/en/

http://www.bjcp.org/study.php

https://cicerone.org/content/certified-beer-server

http://www.aperfectpint.net/Hops.pdf

http://beersensoryscience.wordpress.com

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