Perhaps the most romanticized ingredient in modern beer making, hops are responsible for a wide range of flavors and aromas, in addition to contributing bitterness that counterbalances malty sweetness in beer. In this Vocabrewlary Lesson we take a look at many different ways in which brewers use hops. This is intended to be a broad overview of the options available to brewers for pre-boil, boil, and post-boil hopping.
A seldom-used technique in which hops (usually in whole cone form) are added directly to the mash. Isomerization is extremely low at mash temperatures, and most of the hop oils are thought to be left behind in the mash, having clung to the spent grains. The jury is out on whether and to what extent this technique has any noticeable impact on the finished beer.
Said to lend the perception of a smoother tasting bitterness and more flavor than a traditional 60-90 minute long boil addition, this technique involves adding what would be your 60-90 minute long boil addition to the kettle just as lautering commences. The hops steep in the wort as it is collected in the kettle and remain in the kettle for the duration of the boil.
Traditionally hops are added to the wort just as it comes to a boil in order to give the beer most (or all, as is the case with many styles) of its bitterness. Flavor contributions are minimal and depend on the amount of hops added. Because more bitterness is extracted (via alpha acid isomerization) the longer the hops are boiled, bittering additions are often low in quantity, with higher amounts necessary to achieve the same IBU target as the alpha acid content decreases. For example some styles call for bittering with noble hops, which are on the low end of the alpha acid scale. The amount of these hops added to reach a bitterness level appropriate for the style is large enough that the flavor is evident in the finished beer even when the bittering addition is the only hop addition in the beer.
As the boil progresses, the alpha acids from any hops added will isomerize less, resulting in decreasing levels of bittering contributed. This means that a brewer can add ever higher quantities without over bittering the beer, and higher quantities means more flavor. It is generally accepted among brewers that so-called “flavor” additions begin at around the 30-minute mark. That is, the point at which there remains 30 minutes of boil time. Likewise, beer recipes are written in this manner, where 30-min hop addition means “add these hops when there are 30 minutes left in the boil”. Hop aroma is highly volatile and given enough time will evaporate out of the wort entirely. While bittering additions contribute next to nothing in aroma, flavor additions are where you begin to see some residual aroma compounds stick around until the end of the boil.
Typically, additions made anywhere from 15-minutes until the heat source is turned off (also known as “flame out”or “knock out”) are considered aroma additions. For the same reasons described above, the shorter the boil time, the more hops’ aroma compounds stay in the wort. Very little aroma is volatilized the closer the boil gets to flame out. At the same time, very little bitterness is contributed due to the same lack of boil time. American Pale Ale and IPA are just two styles that make extensive use of aroma additions. For IPA in particular aroma additions can get quite large in order to achieve high levels of hop aroma, which also contributes a lot of flavor. A technique called “hop-bursting” is an example of such an approach, where the brewer adds such a large quantity of aroma addition hops that most of the beer’s bitterness actually comes from this addition.
A popular technique for packing loads of hop aroma and flavor into IPA’s, a hop stand is when, after flame out, hops are added to the boiled wort and allowed to steep for a period of time, typically 20-60 minutes. The wort is then chilled as normal before fermentation begins.
Dry hops are hops added to fermenting or already fermented beer. This technique imparts little-to-no bitterness, some flavor, and big aroma. It is generally accepted among brewers that dry hop aroma is more intense and of a different character than that of an aroma addition.
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