by Mike Retzlaff
There are several forms of hops we have available for brewing. I won’t get into the various varieties and their individual qualities as there are books and charts dedicated to that very subject. Try this site for more information: Hop Chart
Generally speaking, there are 4 forms of hops available. They are leaf, plug, pellet, and hop extract/oil.
Leaf hops are the original form and can serve some special purposes. I’ve found that leaf hops are better for first wort hopping (FWH) but can’t explain why. I’ve tried both leaf and pellet for FWH and tend to prefer the leaf form. If properly stored before use, both forms impart a luscious hop flavor to the beer. In the last several years, “fresh” or “wet” hops have become available. These are freshly picked hops which have not gone through an oast or hop kiln to be dried. My experience with these is quite limited but I find they give a grassy or vegetal aroma and flavor to the beer. From what I’ve experienced, I don’t like using wet hops; your mileage may vary.
Leaf hops do very well in a traditional hop-back (hop-jack) where loose hops are strewn in this vessel as an additional filter bed to separate the the boiled wort from the hops and trub before the wort heads to the chiller. As in the case of the whirlpool, they add flavor and aroma but virtually no extra bitterness.
Plug hops are leaf hops compressed into “cylinders”. They normally break into ½ ounce plugs which are handy in doling out the right amount during the boil. I have talked with a few brewers who didn’t like them because they said that the plugs were hard to break up. Hop plugs are like popcorn or Chinese rice noodles; they virtually explode when dropped into boiling wort; peeling is completely unnecessary. The failure to understand how they work may have made them unpopular and caused a resulting lack of availability from suppliers.
Pelletized hops are the most common form of hops used today. When ground, the lupulin sacs are ruptured and make the alpha and beta acids and other components more readily available to the wort during the boil. The efficiency of this form of hop is better than leaf or plug because of the grinding. Pellets generally are available in T45 and T90 forms. All that means is that the T45 hops contain about 45% of the original leaf hop. The central stem is discarded along with the outer leaf tips. The T90 hops consist of 90% of the hop cones which are ground and extruded into the pellet form. Grinding hops is not a new idea. The American Handybook of Brewing by Wahl and Henius (1902 edition) includes an article about the machinery needed and the time required to grind hops in the brewery.
I have no experience with hop extracts and oils. I’ve read about them and can see the value in their use. They are used by both commercial and amateur brewers to make last minute adjustments to beer before packaging. Hop extract is used for bittering while hop oil is used for aroma.