After the drying stage, the processing for whole hops and pellet hops diverges. Hops intended for pellets are hammer milled, resulting in a powder. This sticky powder is then extruded through a die, forming hard, shiny pellets resembling livestock feed. The ruptured lupulin sacs of the hops serve as both a binder and protective coating, giving the pellets their shiny appearance.
The temperature and speed during the process significantly affect the quality of the pellets. Milling too quickly can cause discoloration, scorching, and oxidation. Therefore, it’s crucial to mill at low speeds and maintain a cool temperature using liquid nitrogen or other methods.
After milling, the pellets are allowed to cool and harden. These cured hops are then accurately weighed, vacuum-sealed in barrier bags, boxed, and stored in a cold environment until sold.
Pellets sink and dissolve, providing a clear advantage in terms of surface area and utilization. The milling process ruptures the lupulin glands, making it easier for alpha acids to isomerize. The increased surface area and availability of alpha acids result in a 10 to 15 percent higher utilization compared to whole hops.
Although this increase may not be significant enough for brewers to adjust hop amounts when switching between the two forms, if you notice a harsh quality in your beer after using pellet hops, it might be worth trying the same recipe with a slightly reduced dose.
The outer shell of lupulin resin in pellet hops helps protect them from oxidation, prolonging their storage life and preserving quality. Pellet hops are also easier to measure, work with, and require less storage space compared to whole hops. These factors provide home brewers with the advantage of having access to a wider range of hop varieties.
Many of the disadvantages of pellet hops stem from their advantages. They sink and dissolve, creating sediment at the bottom of the brew kettle or fermenter. In the fermenter, it can impede siphoning. Additionally, if dry hops are added too early, the hop powder may become covered by dead yeast cells, limiting contact with the wort.
The additional processing involved in milling can negatively impact the aroma quality. Whole lupulin glands allow for a gradual release of essential oils, allowing some oxidation of humulene and other hydrocarbons. The ruptured glands in pellet hops result in a significant loss of these compounds before they have a chance to oxidize.