The Stability of Hop (Humulus lupulus L.) Resins during Long-Period Storage

The stability of alpha-acids, beta-acids and hop storage index (HSI) values under different conditions (aerobic/anaerobic, 4 degrees C/room temperature) was studied in a two-year trial. Six different varieties (Celeia, Aurora, Bobek, Styrian Gold, Savinjski Golding and Styrian Wolf) were used in the form of cones and pellets. Alpha- and beta-acids were determined by HPLC and HSI by spectrophotometry. Anaerobic conditions at 4 degrees C were best for alpha-acids, beta-acids and HSI values; however, 10-35% of the alpha-acids were still lost after two years. The decline was greater (63-99%) under aerobic conditions and at room temperature. Alpha-/beta-acid ratios increased in hop cones and decreased in hop pellets, whereas HSI values increased in all storage conditions. Overall, the performance was better for pellets than for hop cones. Storage conditions, storage form and hop variety had significant effects on the stability of hop resins.

Automated summary

The stability of alpha-acids, beta-acids, and hop storage index (HSI) values were studied under different conditions in a two-year trial. The study found that anaerobic conditions at 4 degrees C were the best for preserving alpha-acids, beta-acids, and HSI values, while aerobic conditions at room temperature resulted in significant losses. The study also observed that the stability of hop resins varied depending on storage conditions, storage form, and hop variety.