Hops play an integral role in the balance of the flavors we have come to expect in beer. The bitterness they add to the beer offsets the sweetness that would otherwise show through from the unfermented sugars of the malt. The balance of hops and malt in the beer can result in a wide range of flavors we have come to know and appreciate.
Hops are the female flower (in the plant world, some species contain both male and female reproductive structures and some contain only one sex) of a plant that produces glands which contain bitter compounds as well as aromatic oils. Botanically speaking, hop plants produce a bine, which is differentiated from a vine in that bines grow up and around other structures using just the stem portion. Vines produce tendrils to anchor and allow them to pull themselves along the substrates.
Generally speaking, hops contribute three things to a beer. First is bitterness, which is extracted at high (boiling) temperature, and up to a point, increases over time. Second is flavor compounds, which are volatilized (boiled off) relatively quickly. Third are aroma compounds, which are volatilized very quickly.
Varying when hops are added during the brewing process changes the amount of each of these components. Adding hops early in the process will contribute more to the bitterness of the beer as the flavor and aroma compounds will have been boiled off. Adding hopes late in the process will contribute more to the flavor and aroma.
Hop lineages fall into three basic categories (in my mind at least): German, British and American. Hops from Germany and the surrounding countries tend to contribute a lower level of bitterness, and give a milder spicy, floral character. British varieties tend to still have a moderate bitterness and provide an earthy spiciness. American hops run the gamut, as there are many US grown strains that are variants of German or UK strains and produce a similar character. What is often viewed as the American hop character through is a high level of bittering paired with a citrus and floral character common to what many of us would expect from an American IPA or pale ale.
Hops typically come packaged in one of two forms, whole ‘leaf’ or pellet. Whole hops are the actual cones of the hop flower, and technically not a leaf at all. Whole cone hops are dried after picking and packaged in an oxygen free package. Oxidation will reduced the shelf life of hops and produce undesirable characters, so the are often purged with non reactive gas. Pellets have been ground up and pressed through a die, and resemble rabbit food, small cylindrical pellets of varying length.
Hops play an important role in the overall balance of the beer and an integral part of the flavor character of the beer. Without hops we’d be left throwing in an assortment of bitter herbs in hopes of creating a drinkable beer. Hops have been used in brewing long enough for brewers to develop a good sense of what can be gained from the numerous varieties available.
Previously in this series:
An Introduction to Brewing Ingredients