Stabilized hop pellets.
In stabilized hop pellets the alpha acids are converted into their calcium and/or magnesium salts. Stabilized pellets are made by mixing hop powder from the hammer mill with an equimolar amount of calcium and magnesium hydroxides (ca. 1.1 kg hydroxide per 100 kgs of hops) and pelletizing in the normal manner. The salt is formed in the die. On storage of stabilized pellets there is little or no deterioration of alpha acid but some isomerization to iso alpha acid may occur. For example, with stabilized pellets from Clusters and Cascade hops there was not net loss of alpha acid + iso alpha acid after one year at 18 to 22 degrees C. Stabilized pellets are isomerized faster during kettle boiling and so can be added later in the boil. In a pilot brewery trial with 1 h boil stabilized pellets were used 56% more efficiently than normal pellets. Essential oils are not stabilized by the process so if it is desired to preserve the aroma the pellets should be cold stored.
Keywords: alpha acid calcium hop pellet hops iso alpha acid isomerisation magnesium salt stabilisation