In beer, hops are the ingredient which balances the malty sweetness by adding bitterness and a wide variety of flavors and aromas. Hops contain essential oils, which provide aromas, and acids (alpha acids and beta acids) which proved bitterness to beer. There are hundreds of different hop varieties grown all over the world and each one has a unique profile of essential oils and acids that add a unique character to beer. Hops can be processed into a few different hop products which include type-100 hop pellets. Also known as hop plugs, t-100 pellets are whole hop cones that have been pressed into a cylinder or cut from a bale and then sliced into discs that are typically 10mm to 30mms thick and weigh roughly 14-28 grams.
Hop plugs are primarily used for “dry hopping” cask ales (primarily in the UK) which is the process of adding hops to the fermenting beer after the primary fermentation is completed in order to add to the pre-existing hop aroma. Since cask ales complete the secondary fermentation in the cask, T-100 pellets are typically thrown directly into the cask. Hop plugs are generally said to be easier to use for dry hopping for small breweries and home brewing because the whole cones, leaves and vegetal matter is much easier to remove from the beer once the dry hopping is complete and the beer is ready for bottling. It is also said that since the hops have not been crushed and processed in type 100 pellets, they haven’t had the opportunity to lose any of their essential oils or resins and they tend to give a slightly fresher aroma to the beer. Because of this, we can also assume that the most common t-100 pellet hop varieties would be popular aroma hops such as Czech Saaz, Centential or Cascade.
When thrown in the boiling wort, type 100 hop pellets break up into whole cones and very prettily float around in the wort. However when hop plugs are used for bittering, other types of pellets (t-90 or t-45) tend to have a higher extraction efficiency by weight than whole hops (about 10% more) and thus, one ounce of other hope pellet types will yield about 10% more IBUs, giving the beer more bitterness, than one ounce of the same hop variety in the form of a hop plug or whole cone. This is why hop plugs are more popular for adding aroma rather than bitterness. Another downfall to Hop plugs is since they are mostly composed of whole hops, they do not store as well as other kinds of hop pellets. The risk of them developing undesirable aroma and flavor attributes, due to exposure to oxygen, is much higher. Hop plugs should be stored in a freezer in an air tight bag for optimal shelf life.
Cask ales are non-pressurized, non-pasteurized and unfiltered beers which have been allowed to go through the secondary fermentation in a cask (barrel or firkin), which essentially means that cask ales have a very short shelf life: approximately 4-5 days. This makes cask ales more common among craft breweries which are typically small scale and locally focused and, therefore, unique and special to each town and city they are brewed in. Before the 12th century, the use of hops in beer was not common place and beer had very low alcohol content. The introduction of hops to brewers, given that they are not only delicious, but also a natural anti-bacterial preservative, meant that beer could have an extended shelf life and a less likely chance of going bad before consumption. Perhaps the act of dry hopping cask ales was an attempt by historic brewers to, not only add beautiful aroma to their beers, but also improve its shelf life.