Unit 3: Hops

Question 1

What is the botanical name for the hop plant?

Answer 1

Humulus Lupulus

Question 2

Because of its climbing nature, what do botanists call this type of plant?

Answer 2

A ‘bine’ specifically NOT a ‘vine’

Question 3

The hop plant is dioecious … what does that mean?

Answer 3

“Dioecious” describes a plant group in which individual plants have either male and female parts, but not both.

“Monoecious” describes the group species in which each plant bears both male and female flowers. Yet another category is the group in which each flower contains both male and female parts, known as “bisexual” or “hermaphroditic” species.

Question 4

Which gender of the hop plant produces the cone-like flowers that we use for beer?

Answer 4

The female; specifically, and like cannabis which is a close relative, it is best if the female remains unpollinated.

Question 5

How do hop farmers ensure that the female plants will remain unpollinated?

Answer 5

By destroying the male plants as soon as they can be identified as male. Few male hop plants exist outside of hop breeding facilities.

Question 6

What is the ‘strig’ of the hop flower?

Answer 6

In the center of each hop cone (flower) is a jointed, zig-zag central stem. This is the strig.

Question 7

What are the ‘bracts’ or ‘bracteolas’?

Answer 7

These are clusters of leaves that attach at each joint of the strig, creating the layers of the cone.

Question 8

What do we find at the base of each bracteole?

Answer 8

At the base of each, near the strig, we find a yellow-gold powder composed of lupulin glands, referred to simply as ‘lupulin’

Question 9

What components are contained in the lupulin?

Answer 9

Resins and oils.

Question 10

What do lupulin resins contribute to beer?

Answer 10

Bitterness.

Question 11

What do lupulin oils contribute to beer?

Answer 11

Flavor and aroma.

Question 12

What are the two main compounds in hop resins?

Answer 12

Alpha acids are also known as ‘Humulones’ that contribute to beer bitterness.

Beta acids are also known as ‘Lupulones’ that contribute to flavor and aroma.

Question 13

What else does this isomerization of alpha acids do?

Answer 13

Intensifies the bitterness

Question 14

When are hops added in the beermaking process?

Answer 14

In the boiling stage, in the ‘brew kettle’

Question 15

How long is a typical boil?

Answer 15

60-90 minutes

Question 16

Why can’t alpha acids bitter beer in their raw state?

Answer 16

As they are, they don’t dissolve readily in wort.

Question 17

Alpha acids require what to have the capacity to add bitterness to beer?

Answer 17

Heat, which turns alpha acids into iso-alpha acids which are far more soluble. Agitation contributes to this change as well.

Question 18

At what rate does this isomerization take place and when are bittering hops added to the boil?

Answer 18

Slowly and so they are added at the beginning of the boil to fully isomerize and extract the bitterness

Question 19

What effect do beta acids, the lupulones Have on beer bittering?

Answer 19

Virtually none

Question 20

In hop oils, how many compounds are there that contribute to flavor and aroma? And what is a hop ‘profile’

Answer 20

Hundreds - hundreds of raw oils and oxidation agents for each of those compounds

Question 21

These aroma and flavor compounds are called what?

Answer 21

Turpenes

Question 22

What are Turpenes?

Answer 22

Terpenes are naturally occurring hydrocarbon chains found in all organisms. Terpenes are important in brewing for their role in hops, specifically, but not isolated to, their presence in hop essential oils. These comprise between 0.5% and 3% of the total hop weight. The relative concentrations of these can be used to identify different hop varieties

Question 23

What are the three types of terpenes?

Answer 23

Terpenes in essential oils are broken down into three types of compounds:

1) hydrocarbons (50%–80%),
2) oxygenated hydrocarbons (20%–50%), and
3) hydrocarbons that contain chemically bound sulfur (1%).

Question 24

What are the most common terpenes in hop oils?

Answer 24

The most common and important terpenes in hop essential oils are:

1) the monoterpene (C10)
2) myrcene and the sesquiterpenes (C15)
3) caryophyllene and
4) Humulene.

These highly aromatic compounds are so water insoluble that they rarely survive into finished beer unless added during dry hopping.

Question 25

Why do flavor and aroma hops need to be added later in the boil?

Answer 25

The more volatile compounds are small in quantity and can disappear in the boil. Adding them later allows them to survive the boil in various amounts that the brewer can control.

Question 26

When do ‘flavor hops’ get added to the boil?

Answer 26

30 minutes before the end of the boil.

Question 27

When do ‘aroma hops’ get added to the boil?

Answer 27

10 minutes before the end of the boil

Question 28

What is ‘whirlpool hopping’?

Answer 28

This is when hops are added immediately after the boil while the wort is still hot. This allows the heat to dissolve the oils without so much evaporation. This exposure to the hops actually goes on in the whirlpool where the hops are separated from the boiled wort.

Question 29

What is ‘dry hopping’?

Answer 29

This is done after primary fermentation, and the beer is pumped through hops. The beer wets the hops completely, and often many cycles of the wort continue for some time. Due to the fact that no volatile oils are boiled off, the benefit of dry hopping is that the brewer can get as much flavor and aroma as possible into the final beer. This can give the beer a floral hop essence and an intense flavor that is desirable in hoppy beer styles like pale ales and IPAs.

Question 30

How high do hop-bines tend to grow?

Answer 30

18-25 feet

Question 31

How are they supported in their growth?

Answer 31

An elaborate trellis system that must bear their weight and any additional stresses caused by wind and weather

Question 32

What happens to the hop plant in winter?

Answer 32

All parts of the plant above ground die. Most hop yards will use this time to maintain trellises.

Question 33

Describe the hop pruning process at various times of the year:

1) Throughout the growing season
2) Midsummer

Answer 33

1) Throughout the season: Hops plant pruning is a process that needs to be kept up throughout the summer if you want your vines to be healthy. Hops are fast growing and tangle easily and pruning hops plants strategically encourages air circulation and seriously discourages disease, bugs, and mildew.

2) Midsummer: In midsummer, once the vines are firmly attached to the trellis above, carefully remove the foliage from the bottom 2 or 3 feet (61-91 cm.). Cutting back hops vines like this will allow air to pass through more easily and protect the vines from all the problems associated with dampness. To further prevent tangling and dampness, keep pruning hop plants down to the ground whenever they send up new shoots out of the soil.

Question 34

What happens in early spring?

Answer 34

1) New hop yards are planted from rhizomes or potted plants. Rhizomes are planted in early spring, and potted plants are planted later after the danger of frost has passed.

2) Initial fertilization begins

3) Trellises are repaired or installed

4) Primary shoots emerge from the hop crowns. In established yards, primary shoots are generally pruned to eliminate early disease inoculum and to set training dates.

5) Twining crews manually tie coir (coconut fiber) or paper twine to the overhead trellis structure, while other workers insert the twine into each hill (hop plant).

6) Drip irrigation tubing is installed or rolled back out in the yards, allowing targeted irrigation to begin when soil conditions and plant growth require additional water.

Question 35

What are training dates and how are they set?

Answer 35

Each farm determines these by looking at a number of factors including growth rates, bloom dates, cone development, and the historical trends of each variety and field location. With the addition of so many varieties on farms now, picking windows of other varieties is noted when selecting training dates. Depending on plant vigor, value of the variety, labor factors, and weather, additional training can be scheduled one or more times to increase the crop size per bine as new shoots emerge.

Question 36

When new shoots develop, how quickly do they grow?

Answer 36

Up to 4 inches per day.

Question 37

When do the bines reach full height of up to 25 feet?

Answer 37

Late June or early July.

Question 38

When do cones develop?

Answer 38

Over several weeks in July.

Question 39

When are hops harvested?

Answer 39

In August and into September

Question 40

How is harvest done?

Answer 40

1) Growers cut the hop bine above the ground and pull it from the trellis.
2) The entire bine goes into the picking house and is fed into the mechanical hop picker
3) The picker removes hops from the bine and removes leaves and other plant debris (bines themselves).
4) The hops are fed into the dryer where moisture content starts at around 70-80% and is reduced to 10%.
5) The hops are dried slowly to preserve the oils in aroma varieties but may be dried faster in hops intended for bittering.

Question 41

What happens after drying?

Answer 41

The hops are baled and sends them to a hop broker for storage and analysis.

Question 42

What are pellet hops?

Answer 42

These hops are chopped finely and then pressed and extruded to about the size of a straw or pencil, and then cut into short sections. These pellets contain all the alpha acids and oils found in the whoe hops and are added at the same points in the boil as whole hops would be.

Question 43

What is a hopback?

Answer 43

A hopback is a vessel that contains hops, and the hot wort can be pumped through after boiling … in a sense its a method that can be used to make the very ‘latest’ late-hopping. This is still done prior to fermentation. This is what differentiates it from dry hopping, where finished, fermented beer is pumped again through hops.

Question 44

What are hop extracts?

Answer 44

These are products that contain the acid resins and essential oils of hops that are extracted by carbon dioxide and concentrated into a paste. When added at the same time as fresh bittering hops would be added these acids isomerize the same way alpha acids do in the presence of heat. They come in cans that don’t require refrigeration and are fully soluble in wort so that they leave no debris that must be subsequently removed.

Question 45

Other hop additives are available that do what?

Answer 45

Some essential oils are available that can add hop flavors at other times than normal hop additions in the brew kettle. These are readily soluble in beer and can be used to enhance the finished aroma.

Question 46

What are iso-alpha acid extracts?

Answer 46

These products have been chemically enhanced to have the ability to add bitterness to beer, and have been modified to prevent the bittering compounds from being ‘light-struck’.

Question 46

Who patented iso-alpha acid extract?

Answer 46

Preparation of light stable hops
Patent number: 7258887

Abstract: Disclosed are methods for the production of light stable hops, useful for the brewing of beer or ale to be stored in clear or green glass containers, which beer or ale will not develop objectionable flavor as a result of exposure to light. Light stable hops are prepared by double extraction of liquid/supercritical CO2 extracted hop solids with ethanol to remove alpha/iso-alpha-acids. Such alpha/iso-alpha-acids may be further removed from the ethanol extraction liquor obtained in the double extraction process by subjecting such liquor to an ion exchange medium, or precipitation by a metal ion, heavy metal ion, or alkali metal ion, to provide an alpha/iso-alpha-acid is free extraction liquor which may be added to the light stable hops residue obtained in the initial double extraction process.

Type: Grant
Filed: March 26, 2002
Date of Patent: August 21, 2007
Assignee: Miller Brewing Company
Inventors: Patrick L. Ting, Henry Goldstein, Aki A. Murakami, Michael VanSanford, Jay R. Refling, John R. Seabrooks, David S. Ryder

Question 47

What are the 4 ‘noble’ hop varieties?

Answer 47

1) Spalt (from Bavaria, south of Nuremburg)
2) Tettnanger (from Tettnang, near Lake Constance)
3) Hallertauer Mittlefrueh (from the Hallertau region of Bavaria)
4) Saaz (from the Zatec region of the Czech Republic)