As homebrewers we all know what hops are for - bitterness, right? But if all you wanted was a bitter beer, you could dump in a few tablespoons of Alum, and get a bitter beer. This article will explore some of the other uses, and techniques when working with hops.
Firstly a short digression on bittering. Bitterness comes from the isomerized alpha acids in hops. The isomerization occurs during boiling, and basically it is a dissolving of the alpha acids that occur with heat and time in the boil. More bitterness comes as you boil the hops longer, up to about 90 minutes, when you have reached your maximum utilization, or extraction of the bitterness.
However as you boil the hops, you are also cooking them, and driving off the more volatile oils, flavors and aromas. A beer made with hops added only for boiling for say 90 minutes, will be bitter, but it will have little in the way of hop flavor and aroma.
In order to get hop flavor in your beer, you really need to add hops for the last 10 minutes of the boil or less. Although you will get some flavor when boiling the hops for longer, not much of it will come through in the beer. I often add hops at the last 10, 5, and 2 minutes of the boil, and as I am using an immersion chiller the hops also remain in the wort as it cools. A good starting point is 1 ounce of total hops added in the last 10 minutes.
Hop aroma comes about differently, and there are three main ways to get hop aroma in your beer. The first is the similar to adding flavor hops, simply add them to wort at the end of the boil, but you need to add them even closer to the end, usually 5 minutes or less. In the example above, I am adding flavor hops in the first (10 minute) addition, and hops for flavor and aroma at 5 and 2 minutes.
You may ask - doesn't this make for an awfully bitter beer? The answer is not really, as you are only boiling these hops for a few minutes, there is very little in the way of isomerization that takes place, and thus very little bittering.
Another way to get hop aroma is to use a hop-back, which is a container (filled with hops) through which the hot wort is run, extracting only the aroma, and very little of the flavor and bitterness. You can see one of these at the Hair of the Dog Brewery where they run the wort out of the boil kettle, through a container (grant) before chilling the wort.
The last way to get aroma in your beer is through dry hopping. The phrase comes from the fact that you are placing dry hops in contact with the beer. Dry hopping is usually done in the secondary or in the serving keg, where whole (as opposed to pelletized) hops are placed in a bag and the bag is placed in the beer. An easy way to do this is cut off the bottom foot or so of an old (clean!) pair of nylons and sanitize briefly in vodka, fill the foot with hops and tie off the top. Place this bag in the secondary or keg, and leave in contact with the beer for a few weeks. A good idea is to add some weight (like clean marbles) to submerge the bag in the beer, as the hops will tend to float. Another good idea is to tie a length of dental floss (unwaxed) to the bag, and hang the other end out the carboy (the stopper will still seal) in order to pull the hops out of the carboy when you are done.
How much dry-hopping is enough? Frankly I think anything less than 1 ounce for two weeks is a waste of time. Brett Rogers and I had two beers at the January meeting where we used 2-3 ounces (each) in two different kegs for over a month, and the beers had a wonderful fresh hop smell.
If you have any questions, Dave Wills (owner of Freshops) and I will be at the next meeting and happy to answer questions.
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