Category:Hops

Hops on the vine.

Hops are the dried flowers of the twining vine (Humulus lupulus) which is part of the hemp family. Hops are used to add bitterness to all modern beer styles, as well as flavor and aroma in many beer styles.

The hop plant

The hop plant, Humulus lupulus, is a climbing vine which grows wild throughout the world. The green, cone-like flowers of the hop plant are used to give beer bitterness as well as a characteristic hop flavor.

Use in brewing

Leaves from the cone flower of the hop plant, or Humulus Lupulus, have been used as a main beer ingredient and for medicinal purposes for hundreds of years. In addition to acting as a preservative, hops lend three qualities to beer: bitterness, flavor, and aroma. How much of each quality a hop contributes to the final beer depends on how long the hop spends in the boil.

History of hops in brewing

In early historical beer styles, various herbs and spices were used to flavor beer. There is some dispute over when and where hops first came into common use, but once hops were introduced they quickly became an expected and indispensible ingredient. A few traditional or experimental beer styles still use herbs and spices in addition to, or occasionally instead of, hops. Historical reproductions of early, unhopped beer styles are referred to as gruit.

Hops as a preservative

One reason hops won out over other herbs is the preservative effects hops have in beer.

The preservative effect of beer also affected the development of certain beer styles; for example, India Pale Ale and several other beer styles intended for export had higher hop bitterness to preserve them on their travels, and often correspondingly higher alcohol levels to balance the beer's flavor.

Modern homebrewers rarely have to worry about adjusting hop levels to preserve beer, although they should be aware of the need for increased care if they are attempting to brew a gruit or other unhopped beer style.

Hop bitterness, aroma, and flavor

There is an inverse correlation between the amount of time the hops spends in the boil, and the amount of actual hop flavor/aroma they impart, while the opposite is true for the amount of bitterness that is extracted. In other words, the longer the hops spend in the boiling wort, the more bitterness they impart, but the less actual hop flavor/aroma is extracted. For these reasons, different hop varieties have different uses.

Certain hops, known as bittering hops, are great for adding bitterness, but don't lend much in the way of good flavor/aroma, so these are added at the beginning of the boil. On the other hand, Aroma hop varieties don't add much bitterness, but lend great hop flavor and aroma, so they are added later in the boil. Other varieties do well in both roles. See the Hop varieties page for more information on choosing bittering or aroma hops.

Hop varieties

See main page: Hop varieties.

Although all hops are a single species, there are dozens or hundreds of varieties of hops available to the homebrewer. The name a reseller or grower uses to describe a hop may tell you a number of things about it, including: the cultivar (genetically distinct subtype) the hop plant belongs to; the region in which the hop was grown, and maybe even the specific company who grew it.

Each of these hop varieties may differ significantly in flavor and aroma, from aggressive, citrusy or grapefruity aromas associated with American hops like Cascade and Amarillo to the almost indefinable floral or spicy aroma associated with the European noble hops like Saaz and Hallertau Hallertauer Mittelfrüher. Hops also vary greatly in the amount of alpha acid they contain, which affects how much bitterness they impart to beer.

For more information on the different hop varieties, how they are distinguished, and what the names of the different varieties mean, as well as lists of individual hop varieties available to brewers and homebrewers, please see the Hop varieties page.

Hop chemistry

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The bittering, flavor, and aroma characteristics of hops are primarily created by two components of the hop: alpha acids and essential oils. The alpha acids are isomerized in the boil, yielding more bitterness the longer the hops are boiled. However, the essential oils evaporate quickly in boiling wort. Understanding these primary chemical components of the hop and the relationship between them will help the brewer better choose and use hops.

Hop products available to homebrewers

Hop cultivation

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Hops are native to most of the world and relatively easy to grow. As a result, many home brewers who also enjoy gardening have tried growing their own hops.

External references

• General Reference
  • Wikipedia:Hops
• Hop variety charts
  • BYO Hops Reference Guide
• History of hops
  • A Short History of Hops