With the second annual IPA day on the horizon (Thursday, August 2), I have decided to lead in with a two-part introduction to hops, the beer ingredient which gives IPA its characteristic, unique, and divisive flavor.
Of the four ingredients “necessary” to make beer — malted barley, water, hops, and yeast — hops have only been considered essential to making all styles of beer since the 16th century, although they have been used in beer for almost one thousand years. The main purpose of using hops is to balance the sweetness of the wort (unfermented beer) produced from the mixture of water and malt during the brewing process. Instead of hops, brewers would use a mixture of herbs called “gruit” to achieve a similar effect. The added benefit of hops — and the reason they have been used for nearly all beer production in the past 500 years — is that they have antibacterial properties which protect the beer from spoilage more than other herbs or spices. As a flavoring, they are often considered analogous to the use of seasoning in cooking. Their effect is to balance and sharpen the predominant sweet malt flavor.
The hop itself, or at least the part of the plant used by brewers, is the female flower cluster of the Humulus Lupulus plant. The perennial plant grows in a vine, so hop growers install trellises which force the plant to grow upwards along the pole. Mature vines can grow up to 25 feet tall, but it takes a couple of years for a new plant to produce a significant amount of flowers which can be harvested for brewing. Hops grow best at latitudes of 40 to 50 degrees, due to the amount of sunlight they receive throughout the year. Conveniently, England, Germany, and Belgium, the three European countries with the strongest brewing traditions, all sit within this band of latitude. This is perhaps another reason hops were selected as the preferred bittering agent in beer. In the United States, almost all commercial hops are grown in Washington and Oregon, although small-scale growers are beginning to produce them in places like Wisconsin and Colorado. New Zealand, which sits at the corresponding 45 degree latitude south of the equator, has recently begun producing some highly desired hop varieties, such as the Nelson Sauvin, which has quickly become one of our favorites here at SanTan.
When hops are harvested in the fall, they are often pelletized, which helps save space for shipping and improves utilization in the brewery (in other words, one pound of non-pelletized hops has less effect on flavor or bitterness than one pound of pelletized hops). Hops are used in all styles of beer to balance the sweetness with their natural bittering compounds. Even though the idea of bitterness sounds unappealing to some, a beer that is completely unhopped would taste unpalatably sweet. Hops are most commonly added during the kettle boil, a 60-90 minute period when the sweet liquid wort is boiled. The reasons for this boil are various, and some of them have nothing to do with hops. But one reason is that the acids in the hops responsible for bittering the beer can only produce this effect if they have been boiled for a sufficiently long time. The side effect of this is that after hops have been boiled for more than 30 minutes, they have lost almost all the flavor and aroma properties normally associated with hops (grassy, citrusy, piney, earthy). For a beer like Hefeweizen, which does not get its flavor and smell from the hops used, a minimal amount of hops will be added at the beginning of the boil simply to balance the sweetness. With an IPA, however, hops will even be added after the boiling — “dry-hopped” — to impart more of the desired hop aroma.
What are these aromas and flavors? Next week, I will discuss the various hop varieties and growing regions, and the effects they impart on beer.